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Resumen Introducción:. En este trabajo se presenta una propuesta para aplicar la meta-heurística Optimización Basada en Mallas Variables (VMO) al problema discreto del Viajero Vendedor (TSP); este modelo explora el espacio de búsqueda a Objetivo partir de una población de soluciones llamada malla que se expande y contrae con la finalidad de encontrar soluciones de buena calidad. En este contexto se modifica el operador de expansión de manera tal que sea aplicable en un dominio discreto, realizando combinaciones entre las soluciones a fin de obtener nuevos nodos. Otro de los elementos que se modifica es el operador de clearing, el cual se encarga de mantener la diversidad de la malla en cada interacción. Metodología: Se resume en este trabajo un estudio de parámetros del modelo VMO utilizando un conjunto de instancias de TSP con diferentes características; además, se puede observar que la propuesta de este trabajo obtiene Resultados: competitivos al compararlos con otros algoritmos de referencia internacional mencionado en el estado del arte. El trabajo está estructurado de la siguiente manera: En el apartado 1 se describe los aspectos fundamentales de problema de estudio TSP. Seguidamente en el segundo se explica el funcionamiento general de VMO, en el tercero se define cada uno de los operadores de expansión y contracción para el problema de estudio. Posteriormente en el apartado cuarto se realiza un estudio de parámetros de la propuesta y un análisis comparativo experimental con los resultados obtenidos con otros algoritmos mencionado en el estado del arte. Conclusiones: Se aplicaron otros operadores de generación de nuevos nodos en el proceso de expansión, donde se realiza una combinación de soluciones de manera que cumpla con las restricciones impuestas por el problema.
Abstract Introduction: This paper presents a proposal to apply the meta-heuristic Optimization Based on Variable Meshes (VMO) to the discreet problem of the Traveler Seller (TSP); This model explores the search space to Objective from a population of solutions called mesh that expands and contracts in order to find good quality solutions. In this context, the expansion operator is modified in such a way that it is applicable in a discrete domain, making combinations among the solutions in order to obtain new nodes. Another element that is modified is the clearing operator, which is responsible for maintaining the diversity of the mesh in each interaction. Methodology: A study of VMO model parameters is summarized in this paper, using a set of TSP instances with different characteristics; In addition, it can be observed that the proposal of this work obtains competitive results when compared with other international reference algorithms mentioned in the state of the art. The work is structured as follows: Section 1 describes the fundamental aspects of the TSP study problem. Then, in the second, the general functioning of VMO is explained, in the third one, each of the expansion and contraction operators is defined for the study problem. Later in the fourth section a study of the parameters of the proposal and an experimental comparative analysis with the results obtained with other algorithms mentioned in the state of the art is made. Conclusions: Other operators of generation of new nodes were applied in the expansion process, where a combination of solutions is made in order to comply with the restrictions imposed by the problem.
Resumo Introdução: Este artigo apresenta uma proposta para aplicar a Otimização meta-heurística Baseada em Malhas Variáveis (VMO) ao problema discreto do Vendedor Vendedor (TSP); Esse modelo explora o espaço de pesquisa para o Objective a partir de uma população de soluções chamada malha que se expande e se contrai para encontrar soluções de boa qualidade. Neste contexto, o operador de expansão é modificado de tal maneira que é aplicável em um domínio discreto, fazendo combinações entre as soluções para obter novos nós. Outro elemento que é modificado é o operador de limpeza, que é responsável por manter a diversidade da malha em cada interação. Metodologia: Um estudo dos parâmetros do modelo VMO é resumido neste artigo, usando um conjunto de instâncias do TSP com diferentes características; Além disso, pode-se observar que a proposta deste trabalho obtém resultados competitivos quando comparados com outros algoritmos de referência internacionais mencionados no estado da arte. O trabalho está estruturado da seguinte forma: a seção 1 descreve os aspectos fundamentais do problema do estudo TSP. Então, no segundo, o funcionamento geral do VMO é explicado, no terceiro, cada operador de expansão e contração é definido para o problema do estudo. Posteriormente na quarta seção é feito um estudo dos parâmetros da proposta e uma análise comparativa experimental com os resultados obtidos com outros algoritmos mencionados no estado da arte. Conclusões: Outros operadores de geração de novos nós foram aplicados no processo de expansão, onde uma combinação de soluções é feita a fim de cumprir as restrições impostas pelo problema.
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Objective To investigate the possible effect of fully knee extension in sitting position with or without hip adduction on quadriceps imbalance in patients with patellofemoral pain syndrome (PFPS) by using surface electromyography (sEMG). Methods sEMG signals of vastus lateralis (VL) and vastus medialis oblique (VMO) muscles from 30 patients with PFPS as PFPS group and 30 healthy subjects as control group were collected, during their fully knee extension in sitting position with or without hip adduction. All the EMG data were then analyzed by extracting time domain indexes, namely, the root mean square (RMS) and integrated EMG (IEMG), to compare the balanced relationship between VL and VMO muscles. Results In PFPS group, there were no significant differences in VL time domain indexes during knee extension in sitting position with or without hip adduction, while statistical differences were found in VMO time domain indexes, and values of RMS and IEMG of VMO were higher under hip adduction, which indicated that the VMO muscle recruitment was strengthened. Conclusions Fully knee extension in sitting position with hip adduction can promote EMG activities of VMO muscles in patients with PFPS, which will help to balance the VL and VMO muscles.
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To clarify the function of the vastus medialis obliquus (VMO) and longus (VML), we investigated the electromyographic properties of superficial quadriceps femoris during fatiguing knee extension task.Ten healthy male and 10 female volunteers participated in this study. The subjects performed fatiguing knee extension task at maximal effort (10 times×10 set at 60 deg/sec). Surface electromyography (EMG) was recorded from the VMO, VML, vastus lateralis(VL) and rectus femoris(RF) during isometric knee extension (knee bent at 60 deg and 30% of the maximal voluntary contraction level) with a 90-sec interval between each set. Knee extension peak torque, integrated EMG (IEMG) and median power frequency (MDF) of four muscles during each set were compared using Dunnett's test.Knee extension peak torque decreased gradually and peak torque decreased significantly starting from set 9 in male subjects, while there was no significant decrease in female subjects. IEMG from VMO and VL increased linearly. IEMG increased significantly from set 7 in VMO and set 6 in VL for both male and female subjects. Then, IEMG from both VML and RF increased significantly starting from set 9 in VML and set 8 in RF in male subjects, while there was no significant change in female subjects.MDF of VMO, VL and RF also increased significantly at timepoints similar to those showing increases in IEMG in male subjects. However, MDF of VML increased significantly from set 4 in male subjects. On the other hand, MDF did not change significantly in female subjects.As a result of this study, it was suggested that VMO and VL were facilitated to maintain target knee extension torque during fatigue. Therefore, it was considered that VML and RF facilitated the maintenance of target torque under fatiguing conditions.
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OBJECTIVE: Inappropriate neural control of the quadriceps femoris muscle group has been implicated in patellofemoral pain syndrome (PFPS) and the methods of biomechanical assessment of PFPS has been developed recently. The aims of the present investigation were to evaluate the effects of therapeutic exercise in the alleviation of PFPS and to develope objective clinical test for PFPS. METHOD: We investigated the onset time of the isometric contraction of vastus medialis oblique muscle (VMO) and the vastus lateralis muscle (VL) under four different conditions: knee flexion and extension in weight bearing (standing) and non-weight bearing (sitting on chair) situations. For each condition, onset times of EMG activities and onset times for VMO and VL were determined from five trials of isometric contraction. In addition, we compared knee flexor and extensor torques in control group and subjects with PFPS. To evaluate the effects of the exercise we compared the onset time difference (onset time of VL-onset time of VM) and quadriceps muscle torque at pre- and post- exercise in PFPS groups. RESULTS: In PFPS group, onset time of VMO during knee extension was significantly longer than the onset time of VL and the knee extensor torque was considerably weaker in comparison with normal group. Although onset time difference was not changed after exercise program, there were significant increase in knee extensor torque in subjects with PFPS. CONCLUSION: The role of exercise in the rehabilitation of quadriceps functions is to reduce the pain, to strengthen the knee extensor, and further accurate diagnostic tools and methods for the result of therapeutic exercise in PFPS are needed.