Interactive and non-interactive hybrid immigrants schemes for ant algorithms in dynamic environments

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Dynamic optimization problems (DOPs) have been a major challenge for ant colony optimization (ACO) algorithms. The integration of ACO algorithms with immigrants schemes showed promising results on different DOPs. Each type of immigrants scheme aims to address a DOP with specific characteristics. For example, random and elitism-based immigrants perform well on severely and slightly changing environments, respectively. In this paper, two hybrid immigrants, i.e., non-interactive and interactive, schemes are proposed to combine the merits of the aforementioned immigrants schemes. The experiments on a series of dynamic travelling salesman problems showed that the hybridization of immigrants further improves the performance of ACO algorithms

Ant colony optimization with direct communication for the traveling salesman problem

This article is posted here with permission from IEEE - Copyright @ 2010 IEEEAnts in conventional ant colony optimization (ACO) algorithms use pheromone to communicate. Usually, this indirect communication leads the algorithm to a stagnation behaviour, where the ants follow the same path from early stages. This occurs because high levels of pheromone are developed, which force the ants to follow the same corresponding trails. As a result, the population gets trapped into a local optimum solution which is difficult to escape from it. In this paper, a direct communication (DC) scheme is proposed where ants are able to exchange cities with other ants that belong to their communication range. Experiments show that the DC scheme delays convergence and improves the solution quality of conventional ACO algorithms regarding the traveling salesman problem, since it guides the population towards the global optimum solution. The ACO algorithm with the proposed DC scheme has better performance, especially on large problem instances, even though it increases the computational time in comparison with a conventional ACO algorithm

A memetic ant colony optimization algorithm for the dynamic travelling salesman problem

Copyright @ Springer-Verlag 2010.Ant colony optimization (ACO) has been successfully applied for combinatorial optimization problems, e.g., the travelling salesman problem (TSP), under stationary environments. In this paper, we consider the dynamic TSP (DTSP), where cities are replaced by new ones during the execution of the algorithm. Under such environments, traditional ACO algorithms face a serious challenge: once they converge, they cannot adapt efficiently to environmental changes. To improve the performance of ACO on the DTSP, we investigate a hybridized ACO with local search (LS), called Memetic ACO (M-ACO) algorithm, which is based on the population-based ACO (P-ACO) framework and an adaptive inver-over operator, to solve the DTSP. Moreover, to address premature convergence, we introduce random immigrants to the population of M-ACO when identical ants are stored. The simulation experiments on a series of dynamic environments generated from a set of benchmark TSP instances show that LS is beneficial for ACO algorithms when applied on the DTSP, since it achieves better performance than other traditional ACO and P-ACO algorithms.This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/01 and Grant EP/E060722/02

Effect of a 12-Week Greek Traditional Dances Program on the Development of Kinesthesis and Dynamic Balance in School-aged Children

The purpose of the present study was to examine the effect of a Greek traditional dances program on the development of kinesthesis and dynamic balance in school-aged children. For this purpose seventeen children, six boys and eleven girls, pupils of elementary school, with their age ranged from 6 to 10 years, took part in the study. All the children received a 12-week program of Greek traditional dances at a frequency of one lesson per week, for 90 minutes. Data collection included pretest and posttest measurements of the kinesthesis and dynamic balance for all the children. Kinesthesis was measured by the kinesthesiometer (Lafayette Instrument Co.) and dynamic balance was measured by the stabilometer platform (Lafayette Instrument Co.). For data analysis, descriptive analysis and the non-parametric tests Wilcoxon of the SPSS ver. 18.0 for windows were used. The level of significance was set to p<0.05. The results showed that after the 12-weeks program of Greek traditional dances there was a significant improvement in the kinesthesis (z=-3.01, p<0.01) and the dynamic balance ability (z=-3.29, p<0.01) of the children. In conclusion, a program with Greek traditional dances with music accompaniment, could lead to significant improvements in children’s abilities, kinesthesis and balance

LIPIDEMIC PROFILE OF MEN PARTICIPATING IN RECREATIONAL TEAM SPORTS AND INACTIVE MEN

The purpose of the present study was to examine the effects of exercise in the form of recreational team sports on resting lipidemic factors of healthy young men. Thirty-four healthy men, 20-37 years old, volunteered to participate in the research. The subjects were separated in two groups, exercisers who participated regularly during the last six months in recreational team sports such as volleyball, basketball and football (Group A, n=17) and inactive men who did not exercise regularly, with a frequency of more than 1 hour per fortnight during the last six months (Group B, n=17). Measurements of anthropomorphological and hemodynamic characteristics were taken place. For the evaluation of lipidemic profile, triglycerides (TG), total cholesterol (TC), low density lipoprotein (LDL) and high density lipoprotein (HDL) at rest were measured, while ratios TC/HDL and LDL/HDL were estimated. For data analysis, descriptive statistics and independent samples t-tests of the SPSS ver. 20.0 for windows was used. The results showed that hemodynamic state of exercisers is better than that of inactive men, since they have lower heart rate (64.82+15.23 vs 69.41+11.61 bpm), systolic blood pressure (114+10.58 vs 115.35+12.90 mmHg), and diastolic blood pressure (72.06+10.91 vs 78.65+12.13 mmHg) at rest. In addition, there were observed significantly more increased HDL (+29.25%, p&lt;0.01), but significantly more decreased TG (-37.87%, p=0.05), TC (-16.84%, p&lt;0.01), LDL (-22.38%, p&lt;0.01), TC/HDL (-35.99%, p&lt;0.001) and LDL/HDL (-44.56%, p&lt;0.001) in the group of young men who participate in regular exercise in the form of team sports compared with the group of young men who didn’t participate in any exercise. Thus, from the results of the present study it is obvious that regular participation in recreational team sports improves participants’ lipidemic profile, which may be a favourable effect for cardiovascular system. Consequently, exercise programs in the form of recreational team sports such as football, volleyball and basketball are recommended for young men, in order to be achieved engagement and adherence to an exercise program aiming on health benefits, especially concerning blood lipids.  Article visualizations

FIBRINOLYTIC ACTIVITY IN ACTIVE AND SEDENTARY MEN AT REST

The purpose of the present study was to examine the effects of exercise in the form of recreational team sports on resting fibronolytic activity of healthy men. Thirty-four healthy men, 20-37 years old, volunteered to participate in the research. The subjects were separated in two groups, exercisers who participated regularly during the last six months in recreational team sports such as volleyball, basketball and football (Group A, n=17) and inactive men who, on average, did not exercise regularly with a frequency of more than 1 hour per fortnight during the last six months (Group B, n=17). Measurements of anthropomorphological and hemodynamic characteristics were taken place. For the evaluation of resting fibrinolytic activity, tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) at rest were measured. For data analysis, descriptive statistics and independent samples t-tests of the SPSS ver. 20.0 for windows was used. The results showed that hemodynamic state of exercisers is better than that of inactive men, since they have lower heart rate (64.82+15.23 vs 69.41+11.61 bpm), systolic blood pressure (114+10.58 vs 115.35+12.90 mmHg), and diastolic blood pressure (72.06+10.91 vs 78.65+12.13 mmHg) at rest. In addition, there were observed significantly more increased resting t-PA levels (t=-3.49, p&lt;0.01), as well as significantly more decreased resting PAI-1 levels (t=2.26, p&lt;0.05) in the group of young men who participate in regular exercise in the form of team sports compared with the group of young men who didn’t participate in any exercise. Consequently, it could be said that physical fitness achieved through the regular participation in recreational team sports, such as football, volleyball and basketball, effect positively on blood fibrinolytic activity. Thus, aiming on fibrinolytic activity improvement, the regular participation in recreational team sports should be emphasized.  Article visualizations

The Examination of Injuries in Dancers

The purpose of the present study was to examine the incidence of the injuries in dancers. A hundred and sixty eight dancers (135 women and 33 men) 23.17+6.43 years old, members of different dancing clubs, participated in the research. All the subjects participated only in dancing programs for learning, performing and practicing in any kind of dance and no other form of physical activity, and filled the instrument of measurements concerning general questions as well as questions about injury incidence. For data analysis, descriptive analysis and Pearson chi-square test of the SPSS version 17 for windows, were used. From the results it was shown that the biggest percentage of dancers take hip-hop (25.1%) and Latin American lessons (18.6%). Moreover, the dancers are involved in European dances, classic ballet, modern dance, oriental dances and Greek dances. The subjects participated in dance programs for 4.44 + 4.45 years, 3.16+1.63 days a week, for 2.29+1.30 hours a day. According to the dancersrsquo statements, 44.62% of them have suffered an injury. The most usual kinds of injuries are muscle strains (22.9%), muscular spasms-cramps (20.15%), callus (13.18%), sprains (12.53%), blisters (11.80%) and abrasions (11.10%). Also, in smaller percentages follow the fractures (3.48%), hematomas (3.48%) and dislocations (1.38%). The most significant causes of the injuries are poor warming-up (21.92%), fatigue (16.64%), clumsiness (15.68%), bad technique (10.48%), and concentration (10%), and nbspin smaller percentages performance pressure (7.12%), shoes (5.2%), partner and floor (4.8% both), hour of the day (1.44%), as well as competition and space tightness (7.96% both). Most of the dancers of the present sample (34%), who had an injury, overcame it with medication, 25% needed further medical examinations and 20% overcame the injury with rehabilitation. 16% of the dancers needed rest, while fortunately, only 5% overcame the injury with a surgery. Finally, most of the dancers of the present sample (63.76%) consider that dance teachers, as well as dancing clubs, are concerned very much with injuries prevention (63.76%). Consequently, recognizing, resolving, but above all, preventing the causes of injuries is very important concerning injuriesrsquo avoidance, good physical condition of dancers, reduction of training time loss, continuation of professional career, and continuation of dancing activity of those who have finished their career or are not professionally engaged in dancing

THE EFFECTS OF EXERCISE ON THE REHABILITATION OF KNEE LIGAMENT INJURIES IN ATHLETES

The purpose of the present study was to examine the effects of exercise on the rehabilitation of knee ligament injuries in athletes and to identify what the injured athletes consider as the most effective treatment concerning their rehabilitation, through the administration of a reported condition inquiry. Two hundred ninety six healthy subjects, 22,59+6,31 years old, participated in the research. All the subjects were active or former athletes, competed or had competed in athletic clubs throughout Greece, in various team sports or individual sports and competing categories and had suffered a knee ligament injury in their career as athletes. The effects of exercise on the rehabilitation of knee ligament injuries were measured through a scale of measurements. For data analysis was used the descriptive analysis of the SPSS version 20 for Windows. Data processing showed that the highest percentage of the knee injuries (43,80%) concerns anterior cruciate ligament (ACL) rupture, 34,40% partial or total meniscus rupture, 15,60% ligament injuries and 6,20% medial collateral ligament (MCL) or lateral collateral ligament (LCL) rupture. More than half of the knee injuries (53,10%), namely ruptures of ACL (76,50%), the partial-total rupture of meniscus (17,60%), and the patella dislocations and partial ruptures of MCL and LCL (5,90%), were treated surgically, combined with abstaining from training and matches, medication, bandage usage, immobilization with plaster-brace, medical examinations, physiotherapies, and special therapeutic exercise. The rest of the cases of the knee injuries (46,90%), namely all the cases of ligament over-voltages, ¾ of the meniscus ruptures, half of the patella dislocations and partial ruptures of MCL and LCL, as well as 1,25% of ACL rupture, were treated conservatively, with different combinations of  physiotherapies, special therapeutic exercises, abstention from training and games, medication, bandage usage, immobilization with plaster-brace, further medical examinations. In addition, almost all the injured athletes (except a 6,20%) did a combination of exercise modes for the rehabilitation of their knee ligament injury. More specifically, 18,80% did exercises with straps, resistance bands, weightbearing and isokinetic machine. In addition, 15,60% did exercises with straps, resistance bands, weightbearing, exercises in the water and isokinetic machine and the same percentage (15,60%) did exercises with straps, resistance bands, weightbearing and exercises in the water. 12,50% did exercises with resistance bands and weightbearing, 9,40% did exercises with resistance bands and in smaller percentages the athletes did exercises in the water and gaiting (6,20%), exercises with straps, resistance bands and weightbearing (6,20%), exercises with straps and resistance bands (3,10%), exercises with isokinetic machine and exercises in the water (3,10%), as well as exercises with resistance bands, exercises in the water and in the isokinetic machine (3,10%). In addition, 93,80% of the athletes stated that their knee ligament injury is completely or partially restored. Concerning the athletes’ opinions,  43,80% consider that the most effective treatment for the rehabilitation of their knee ligament injury was strengthening with weightbearing and resistance bands. Likewise, 35,30% of the athletes who underwent surgery consider strengthening mainly by weightbearing and resistance bands as the most effective treatment for the rehabilitation of their injury. In conclusion, according to the opinions of the athletes, who treated their knee ligament injury both non-operatively and operatively, the most effective treatment for the rehabilitation of the knee ligament injury was exercise in the mode of weightbearing and resistance bands. Thus, it could be said that exercise brings about significant positive effects on the rehabilitation of the knee ligament injury. Consequently, exercise should be an integral part of the knee ligament injury rehabilitation and prevention.   Article visualizations

A survey of swarm intelligence for dynamic optimization: algorithms and applications

Swarm intelligence (SI) algorithms, including ant colony optimization, particle swarm optimization, bee-inspired algorithms, bacterial foraging optimization, firefly algorithms, fish swarm optimization and many more, have been proven to be good methods to address difficult optimization problems under stationary environments. Most SI algorithms have been developed to address stationary optimization problems and hence, they can converge on the (near-) optimum solution efficiently. However, many real-world problems have a dynamic environment that changes over time. For such dynamic optimization problems (DOPs), it is difficult for a conventional SI algorithm to track the changing optimum once the algorithm has converged on a solution. In the last two decades, there has been a growing interest of addressing DOPs using SI algorithms due to their adaptation capabilities. This paper presents a broad review on SI dynamic optimization (SIDO) focused on several classes of problems, such as discrete, continuous, constrained, multi-objective and classification problems, and real-world applications. In addition, this paper focuses on the enhancement strategies integrated in SI algorithms to address dynamic changes, the performance measurements and benchmark generators used in SIDO. Finally, some considerations about future directions in the subject are given

Ant Colony Optimization With Local Search for Dynamic Traveling Salesman Problems

For a dynamic traveling salesman problem (DTSP), the weights (or traveling times) between two cities (or nodes) may be subject to changes. Ant colony optimization (ACO) algorithms have proved to be powerful methods to tackle such problems due to their adaptation capabilities. It has been shown that the integration of local search operators can significantly improve the performance of ACO. In this paper, a memetic ACO algorithm, where a local search operator (called unstring and string) is integrated into ACO, is proposed to address DTSPs. The best solution from ACO is passed to the local search operator, which removes and inserts cities in such a way that improves the solution quality. The proposed memetic ACO algorithm is designed to address both symmetric and asymmetric DTSPs. The experimental results show the efficiency of the proposed memetic algorithm for addressing DTSPs in comparison with other state-of-the-art algorithms