77 resultados para Músculos motores

em Universidade Federal do Rio Grande do Norte(UFRN)


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Equipment maintenance is the major cost factor in industrial plants, it is very important the development of fault predict techniques. Three-phase induction motors are key electrical equipments used in industrial applications mainly because presents low cost and large robustness, however, it isn t protected from other fault types such as shorted winding and broken bars. Several acquisition ways, processing and signal analysis are applied to improve its diagnosis. More efficient techniques use current sensors and its signature analysis. In this dissertation, starting of these sensors, it is to make signal analysis through Park s vector that provides a good visualization capability. Faults data acquisition is an arduous task; in this way, it is developed a methodology for data base construction. Park s transformer is applied into stationary reference for machine modeling of the machine s differential equations solution. Faults detection needs a detailed analysis of variables and its influences that becomes the diagnosis more complex. The tasks of pattern recognition allow that systems are automatically generated, based in patterns and data concepts, in the majority cases undetectable for specialists, helping decision tasks. Classifiers algorithms with diverse learning paradigms: k-Neighborhood, Neural Networks, Decision Trees and Naïves Bayes are used to patterns recognition of machines faults. Multi-classifier systems are used to improve classification errors. It inspected the algorithms homogeneous: Bagging and Boosting and heterogeneous: Vote, Stacking and Stacking C. Results present the effectiveness of constructed model to faults modeling, such as the possibility of using multi-classifiers algorithm on faults classification

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This work presents a diagnosis faults system (rotor, stator, and contamination) of three-phase induction motor through equivalent circuit parameters and using techniques patterns recognition. The technology fault diagnostics in engines are evolving and becoming increasingly important in the field of electrical machinery. The neural networks have the ability to classify non-linear relationships between signals through the patterns identification of signals related. It is carried out induction motor´s simulations through the program Matlab R & Simulink R , and produced some faults from modifications in the equivalent circuit parameters. A system is implemented with multiples classifying neural network two neural networks to receive these results and, after well-trained, to accomplish the identification of fault´s pattern

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Induction motors are one of the most important equipment of modern industry. However, in many situations, are subject to inadequate conditions as high temperatures and pressures, load variations and constant vibrations, for example. Such conditions, leaving them more susceptible to failures, either external or internal in nature, unwanted in the industrial process. In this context, predictive maintenance plays an important role, where the detection and diagnosis of faults in a timely manner enables the increase of time of the engine and the possibiity of reducing costs, caused mainly by stopping the production and corrective maintenance the motor itself. In this juncture, this work proposes the design of a system that is able to detect and diagnose faults in induction motors, from the collection of electrical line voltage and current, and also the measurement of engine speed. This information will use as input to a fuzzy inference system based on rules that find and classify a failure from the variation of thess quantities

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Electrical Motors transform electrical energy into mechanic energy in a relatively easy way. In some specific applications, there is a need for electrical motors to function with noncontaminated fluids, in high speed systems, under inhospitable conditions, or yet, in local of difficult access and considerable depth. In these cases, the motors with mechanical bearings are not adequate as their wear give rise to maintenance. A possible solution for these problems stems from two different alternatives: motors with magnetic bearings, that increase the length of the machine (not convenient), and the bearingless motors that aggregate compactness. Induction motors have been used more and more in research, as they confer more robustness to bearingless motors compared to other types of machines building with others motors. The research that has already been carried out with bearingless induction motors utilized prototypes that had their structures of stator/rotor modified, that differ most of the times from the conventional induction motors. The goal of this work is to study the viability of the use of conventional induction Motors for the beringless motors applications, pointing out the types of Motors of this category that can be more useful. The study uses the Finite Elements Method (FEM). As a means of validation, a conventional induction motor with squirrel-cage rotor was successfully used for the beringless motor application of the divided winding type, confirming the proposed thesis. The controlling system was implemented in a Digital Signal Processor (DSP)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The biodiesel use has become important due to its renewable character and to reduce environmental impacts during the fuel burning. Theses benefit will be valid if the fuel shows good performance, chemistry stability and compatibility with engines. Biodiesel is a good fuel to diesel engines due to its lubricity. Then, the aimed of this study was to verify the physicalchemistry properties of biodiesel and their correlations with possible elastomers damage after biodiesel be used as fuel in an injection system. The methodology was divided in three steps: biodiesels synthesis by transesterification of three vegetable oil (soybean, palm and sunflower) and their physical-chemistry characterization (viscosity, oxidative stability, flash point, acidity, humidity and density); pressurized test of compatibility between elastomers (NBR and VITON) and biodiesel, and the last one, analyze of biodiesels lubricity by tribological test ball-plan( HFRR). Also, the effect of mixture of biodiesel and diesel in different concentrations was evaluated. The results showed that VITON showed better compatibility with all biodiesel blends in relation to NBR, however when VITON had contact with sunflower biodiesel and its blends the swelling degree suffer higher influences due to biodiesel humidity. For others biodiesels and theirs blends, this elastomer kept its mechanical properties constant. The better tribological performance was observed for blends with high biodiesel concentration, lower friction coefficient was obtained when palm biodiesel was used. The main mechanisms observed during the HFRR tests were abrasive and oxidative wear

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Patellofemoral pain syndrome is defined as a fore or retro patellar pain and it has multifactorial etiology, where the bad patellar alignment is the most acceptable hypothesis. However proximal factors to the knee, as the debility of the muscles of the hip, have been demonstrated as a contributing factor to the appearing of that syndrome. Purpose: To evaluate if exists a relation between the hip muscles performance and the development of the SDPF. Methods: Thirty women took part in this study. They were divided in two groups; a control group (fifteen asymptomatic subjects) and an experimental group (fifteen subjects with the diagnosis of SDPF). The muscle performance was evaluated in an isokinetic dynamometer, where it was verified the peak torque (PT), PT to body weight, PT time and the agonist/antagonist relation. It was also analyzed the electromyographic activity of the middle gluteus. The data was analyzed by the not paired t test at a significance level of 5%. Results:. Didn t have significant difference to the PT of the abductor muscles (p = 0,46) and lateral rotators of the hip (p = 0,17) between groups. Also didn t have significant difference to the PT values by the body weight, to these muscle groups either (p = 0,10 e p = 0,11, respectively). Didn t have significant difference between the amplitude of the signal (p = 0,05) and the onset of medium gluteus (p = 0,25) between the groups. Conclusion: In the experimental conditions realized, the study didn t demonstrate a relation between performance the hip muscles behavior and the development of the SDPF

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The objective was measured by surface electromyography (EMGs), the activity of inspiratory muscles during incremental test in subjects with hemiparesis and show its correlation with the Functional Independence Measure (FIM). Were included in the study 32 individuals hemiparetics and 14 healthy as control group. We performed an evaluation of lung function and anthropometric data. The EMGs were performed during the incremental test with Threshold ® (15, 30, 45 and 60% of MIP) and during maximal inspiratory pressure (MIP). The electromyographic findings were calculated by the signal amplitude (RMS). All data were initially analyzed by Kolmogorov-Smirnov, the anthropometric characteristics of both groups were tested with the Levene and then intra-subject analysis (hemiparetic hemithorax and healthy hemithorax) and inter-group analysis (experimental group and control group) by paired and non-paired Student t tests and Pearson correlation. In intra-subject comparison was observed less activation (p <0.01) of the sternocleidomastoid muscle, scalene and diaphragm paretic side in both sexes - for the Threshold ® incremental test (15, 30, 45 and 60% of the MIP) and during maximal inspiratory pressure (MIP). In inter-group comparison, there was reduced activity in the diaphragm and the scalene, in hemiparetics males and females, respectivelly, during the same test. Our results demonstrate the existence of reduced electromyographic activity of inspiratory muscles in hemiparetics, including changes between different genders and suggests the need of further studies to assess the effects of specific training of inspiratory muscles.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The reduction of physiological capacity present in the process of aging causes a marked decline in lung function. The exercise does promote several positive changes in the physical health of people and protect the cardiorespiratory function. The aim of this study was to investigate the effects of a program of Pilates exercices on the strengh and electrical activity of respiratory muscles of elderly. This is a randomized, controlled clinical trial, evaluating 33 elderly aged 65 and 80 (70.88 ± 4.32), healthy, sedentary, without cognitive impairment and able the practice physical activity. The sample was divided into two groups, one experimental group with 16 elderly women who did Pilates exercises and a control group (17) that was not submitted to the exercises, but received educational booklets on aging and health care. The elderly were evaluated initially and after a period of three months, taking into account the Maximal Inspiratory Pressure (MIP) and Maximal Expiratory Pressure (MEP), obtained by Manovacuometry and intensity of EMG activity was measured using the values of Root Mean Square (RMS) for the diaphragm and rectus abdominis muscles, during the course of diaphragmatic breathing and MIP maneuver. Data were analyzed using SPSS version 17.0. For all tests, we used a significance level or p value < 0.05 and confidence interval 95%. RMS in diaphragm and rectus abdominis muscles in both tests increased, but the data were significant for the rectus abdominis during diaphragmatic breathing (p = 0.03) and the diaphragm during the MIP maneuver (p = 0.01). There was no significant variation of the MIP and MEP. Pilates exercises were responsible for increasing the electrical activation of the diaphragm and rectus abdominis muscles in a group of healthy elderly, but had no influence on changes in strength of respiratory muscles

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Asthma treatment aims to achieve and maintain the control of the disease for prolonged periods. Inspiratory muscle training (IMT) may be an alternative in the care of patients with asthma, and it is used as a complementary therapy to the pharmacological treatment. Thus, the aim of this study was to investigate the effects of a domiciliary program of IMT on the electromyographic activity of the respiratory muscles in adults with asthma. This is a clinical trial in which ten adults with asthma and ten healthy adults were randomized into two groups (control and training). The electrical activity of inspiratory muscles (sternocleidomastoid (ECM) and diaphragm) was obtained by a surface electromyography. Furthermore, we assessed lung function (spirometry), maximal inspiratory pressure - MIP - (manometer). The functional capacity was evaluated by six minute walk test. Participants were assessed before and after the IMT protocol of 6 weeks with POWERbreathe® device. The training and the control groups underwent IMT with 50% and 15 % of MIP, respectively. The sample data were analyzed using SPSS 20.0, attributing significance of 5 %. Were used t test, ANOVA one way and Pearson correlation. It was observed an increase in MIP, after IMT, in both training groups and in healthy sham group (P < 0.05), which was accompanied by a significant increase in ECM activity during MIP in healthy training group (1488 %) and in asthma training group (ATG) (1186.4%). The ATG also showed a significant increase in diaphragm activity in basal respiration (48.5%). Functional capacity increased significantly in the asthma sham group (26.5 m) and in the asthma training group (45.2 m). These findings suggest that IMT promoted clinical improvements in all groups, especially the ATG, which makes it an important complementary treatment for patients with asthma

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Parkinson's disease (PD) is one of the most common neurodegenerative brain disorders and is characterized primarily by a progressive degeneration of dopaminergic neurons nigroestriatais. The main symptoms of this disease are motor alterations (bradykinesia, rigidity, tremor at rest), which can be highly disabling in advanced stages of the condition. However, there are symptomatic manifestations other than motor impairment, such as changes in cognition, mood and sensory systems. Animal models that attempt to mimic clinical features of PD have been used to understand the behavioral and neural mechanisms underlying neurophysiological disturbance of this disease. However, most models promote an intense and immediate motor impairment, consistent with advanced stages of the disease, invalidating these studies for the evaluation of its progressive nature. The administration of reserpine (a monoamine depletor) in rodents has been considered an animal model for studying PD. Recently we found that reserpine (in doses lower than those usually employed to produce the motor symptoms) promotes a memory deficit in an aversive discrimination task, without changing the motor activity. It was suggested that the administration of this drug in low doses can be useful for the study of memory deficits found in PD. Corroborating this data, in another study, acute subcutaneous administration of reserpine, while preserving motor function, led to changes in emotional context-related (but not neutral) memory tasks. The goal of this research was to study the cognitive and motor deficits in rats repeatedly treated with low doses of reserpine, as a possible model that simulates the progressive nature of the PD. For this purpose, 5-month-old male Wistar rats were submitted to a repeated treatment with vehicle or different doses of reserpine on alternate days. Cognitive and motor parameters and possible changes in neuronal function were evaluated during treatment. The main findings were: repeated administration of 0.1 mg / kg of reserpine in rats is able to induce the gradual appearance of motor signs compatible with progressive features found in patients with PD; an increase in striatal levels of oxidative stress and changes in the concentrations of glutamate in the striatum were observed five days after the end of treatment; in animals repeatedly-treated with 0. 1 mg/kg, cognitive deficits were observed only after the onset of motor symptoms, but not prior to the onset of these symptoms; 0.2 mg / kg reserpine repeated treatment has jeopardized the cognitive assessment due to the presence of severe motor deficits. Thus, we suggest that the protocol of treatment with reserpine used in this work is a viable alternative for studies of the progressive appearance of parkinsonian signs in rats, especially concerning motor symptoms. As for the cognitive symptoms, we suggest that more studies are needed, possibly using other behavioral models, and / or changing the treatment regimen

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Aim : To evaluate and to standardize surface electromyography (sEMG) normalization procedures for respiratory muscles by comparing muscle activation during Maximal Voluntary Isometric Contraction (MVIC) and Maximal Respiratory Pressures (MIP, MEP and sniff test). Methods: Healthy subjects were evalua ted regarding demographics, spirometry and sEMG during the five maneuvers: sniff test, MIP , MEP and Maximal Voluntary Isometric C ontraction (MVIC) of RA, SCM and SC A . For electrode placement, skin was prepared with abrasion, followed by shaving in the foll owing regions for acquisition of el ectromyographic signals: (1) SC M: lower third of the distance between the mastoid process and t he sternoclavicular joint; (2) SC A : 5 cm to the right from the sternoclavicular joint and at this point, up to 2 cm; and (3 ) RA: the level of umbilicus, 4 cm to the right. In electromyographic variables analysis , the data normality was assessed by Shapiro - Wilk test. Comparisons among studied maneuvers were performed by Friedman Test and Dunn’s post - hoc for multiple comparisons a mong inspiratory maneuvers, and Mann Whitney test for expiratory maneuvers. Subgroups differences between genders were performed by Student's t test or Mann - Whitney test according to data normality. Results: 35 subjects participated in the study, b ut 5 we re excluded (BMI> 25 kg/ m²). Sample consisted of 30 subjects (1 5 women), mean age 27.3±7.43 years, BMI 22.2 ± 1.69 kg/m² and spirometric indices within normal limits. Specific MVIC for SCM, SCA and RA showed the highest RMS. When we grouped sample into gender we found no difference among RMS values for the studied SCM maneuvers, while for SCA, MVIC SCM / SCA was the one with the highest RMS and for RA, MVIC RA in men. Once considering women, MVIC SCM/SCA showed the highest RMS for SCM, SCA and MVIC RA showed t he highest value for RA. Conclusion: MVIC for SCM, SCA and RA muscles showed the highest RMS values. When comparing RMS between the studied groups, there was no significant difference between men and women.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background: The inspiratory muscle training (IMT) has been considered an option in reversing or preventing decrease in respiratory muscle strength, however, little is known about the adaptations of these muscles arising from the training with charge. Objectives: To investigate the effect of IMT on the diaphragmatic muscle strength and function neural and structural adjustment of diaphragm in sedentary young people, compare the effects of low intensity IMT with moderate intensity IMT on the thickness, mobility and electrical activity of diaphragm and in inspiratory muscles strength and establish a protocol for conducting a systematic review to evaluate the effects of respiratory muscle training in children and adults with neuromuscular diseases. Materials and Methods: A randomized, double-blind, parallel-group, controlled trial, sample of 28 healthy, both sexes, and sedentary young people, divided into two groups: 14 in the low load training group (G10%) and 14 in the moderate load training group (G55%). The volunteers performed for 9 weeks a home IMT protocol with POWERbreathe®. The G55% trained with 55% of maximal inspiratory pressure (MIP) and the G10% used a charge of 10% of MIP. The training was conducted in sessions of 30 repetitions, twice a day, six days per week. Every two weeks was evaluated MIP and adjusted the load. Volunteers were submitted by ultrasound, surface electromyography, spirometry and manometer before and after IMT. Data were analyzed by SPSS 20.0. Were performed Student's t-test for paired samples to compare diaphragmatic thickness, MIP and MEP before and after IMT protocol and Wilcoxon to compare the RMS (root mean square) and median frequency (MedF) values also before and after training protocol. They were then performed the Student t test for independent samples to compare mobility and diaphragm thickness, MIP and MEP between two groups and the Mann-Whitney test to compare the RMS and MedF values also between the two groups. Parallel to experimental study, we developed a protocol with support from the Cochrane Collaboration on IMT in people with neuromuscular diseases. Results: There was, in both groups, increased inspiratory muscle strength (P <0.05) and expiratory in G10% (P = 0.009) increase in RMS and thickness of relaxed muscle in G55% (P = 0.005; P = 0.026) and there was no change in the MedF (P> 0.05). The comparison between two groups showed a difference in RMS (P = 0.04) and no difference in diaphragm thickness and diaphragm mobility and respiratory muscle strength. Conclusions: It was identified increased neural activity and diagrammatic structure with consequent increase in respiratory muscle strength after the IMT with moderate load. IMT with load of 10% of MIP cannot be considered as a placebo dose, it increases the inspiratory muscle strength and IMT with moderate intensity is able to enhance the recruitment of muscle fibers of diaphragm and promote their hypertrophy. The protocol for carrying out the systematic review published in The Cochrane Library.