A noise-filtering event generator for PIDPlus controllers     

Luca Merigo  Manuel Beschi  Fabrizio Padula  Antonio Visioli 《Journal of The Franklin Institute》2018,355(2):774-802

In this paper we propose a new event generator, which has strong noise-filtering capabilities, to be used in event-based control systems with a PIDPlus controller. An approximate frequency analysis is performed in order to characterize the event generator system and tuning guidelines are provided for its design parameter. Simulation and experimental results obtained with a laboratory setup demonstrate the effectiveness of the methodology in providing a satisfactory performance related to set-point and load disturbance step responses with a total variation that is significantly reduced with respect to the standard cases.  相似文献   

Sailing in all winds: Technological search over the business cycle     

Daniela Silvestri  Massimo Riccaboni  Antonio Della Malva 《Research Policy》2018,47(10):1933-1944

Business cycles modify firms’ incentives to innovate and the direction of innovation. By introducing a new measure of patent unconventionality this paper explores the impact of the business cycle on firms’ technological search strategies. We find that during upturns firms generate inventions characterized by a higher level of technological unconventionality. We also find that financially resilient and diversified firms produce more unconventional patents. While patent unconventionality is associated with technological impact and market value, firms extract more value by investing in unconventional inventions in downturns.  相似文献   

Protective effects of photobiomodulation against resistance exercise-induced muscle damage and inflammation in rats     

Helenita Antonia de Oliveira  Ednei Luiz Antonio  Flávio André Silva  Paulo de Tarso Camillo de Carvalho  Regiane Feliciano  Amanda Yoshizaki 《Journal of sports sciences》2018,36(20):2349-2357

We investigated whether low-level laser therapy (LLLT) prior to or post resistance exercise could attenuate muscle damage and inflammation. Female Wistar rats were assigned to non-LLLT or LLLT groups. An 830-nm DMC Laser Photon III was used to irradiate their hind legs with 2J, 4J, and 8J doses. Irradiations were performed prior to or post (4J) resistance exercise bouts. Resistance exercise consisted of four maximum load climbs. The load work during a resistance exercise bout was similar between Control (non-LLLT, 225 ± 10 g), 2J (215 ± 8 g), 4J (210 ± 9 g), and 8J (226 ± 9 g) groups. Prior LLLT did not induce climbing performance improvement, but exposure to 4J irradiation resulted in lower blood lactate levels post-exercise. The 4J dose decreased creatine kinase and lactic dehydrogenase levels post-exercise regardless of the time of application. Moreover, 4-J irradiation exposure significantly attenuated tumor necrosis factor alpha, interleukin-6, interleukin-1β, cytokine-induced neutrophil chemoattractant-1, and monocyte chemoattractant protein-1. There was minor macrophage muscle infiltration in 4J-exposed rats. These data indicate that LLLT prior to or post resistance exercise can reduce muscle damage and inflammation, resulting in muscle recovery improvement. We attempted to determine an ideal LLLT dose for suitable results, wherein 4J irradiation exposure showed a significant protective role.  相似文献   

The effects of service convenience and perceived quality on perceived value,satisfaction and loyalty in low-cost fitness centers     

Jerónimo García-Fernández  Pablo Gálvez-Ruíz  Jesús Fernández-Gavira  Luisa Vélez-Colón  Brenda Pitts  Ainara Bernal-García 《Sport Management Review》2018,21(3):250-262

Due to its importance in fitness centers, a number of authors have explored and analyzed loyalty. However, two characteristics not yet examined are service convenience in fitness center chains and low-cost fitness centers (an emerging business model). In the present study, the authors sought to understand the relationship among perceived quality and service convenience on perceived value, satisfaction, and client loyalty in low-cost fitness centers. Clients (N = 763; 381 women and 382 men) from three low-cost Spanish fitness centers were surveyed, revealing a positive relationship among the variables studied. Findings demonstrate the importance of proper management of non-monetary sacrifices and perceived quality by the managers of these sport organizations, since client loyalty could depend on factors of these emerging sport models.  相似文献   

Engines at top speed! Using the adventures of a comic book motorsports hero as an approach to understanding recent French history     

Sébastien Laffage-Cosnier  Noemi García-Arjona  Christian Vivier 《Sport in History》2018,38(1):1-22

Jean Graton created a series of comic books called Michel Vaillant, and its motorsports hero bore the same name. Michel Vaillant made his first appearance in 1957 in the weekly Tintin. Young French boys who loved adventure, sports and car racing greeted this publication with great enthusiasm. We studied the first series of Michel Vaillant, composed of 16 comic books produced in the 1960s. We have departed from traditional approaches and have based our method on the analysis of the sources of Graton’s inspiration. We link these sources to the comics’ text bubbles, visual signs and iconic meanings of the drawings. Our analysis of the comics’ iconography based on the establishment of a mass culture dedicated to the automobile brings to light the existence of an urge to go beyond the limits of tradition. Our research highlights that the success of Michel Vaillant is due, in the main, to the series’ detailed knowledge of the automobile sports industry, and to the myths of speed, youth and progress that it promulgates – myths in which its young male readers could see themselves reflected and which would also prepare them for the future.  相似文献   

Effects of a contrast training programme on jumping,sprinting and agility performance of prepubertal basketball players     

Pedro Ángel Latorre Román  Francisco Javier Villar Macias  Felipe García Pinillos 《Journal of sports sciences》2018,36(7):802-808

The purpose of this study was to examine the effects of a 10 week contrast training (CT) programme (isometric + plyometric) on jumping, sprinting abilities and agility performance in prepubertal basketball players. Fifty-eight children from a basketball academy (age: 8.72 ± 0.97 years; body mass index: 17.22 ± 2.48 kg/m²) successfully completed the study. Participants were randomly assigned to experimental groups (EG, n = 30) and control groups (CG, n = 28). The CT programme was included in the experimental group’s training sessions – twice a week – as part of their usual weekly training regime. This programme included 3 exercises: 1 isometric and 2 plyometric. Jumping, sprinting and agility performance were assessed before and after the training programme. Significant differences were found in posttest between EG and CG in sprint and T-test: EG showed better results than CG. Furthermore, there were significant differences in posttest-pretest between EG and CG in squat jump, countermovement jump, drop jump, sprint and T-test with the EG showing better results than CG. The CT programme led to increases in vertical jump, sprint and agility levels, so that the authors suggest that prepubertal children exhibit high muscular strength trainability.  相似文献   

Effect of contact and no-contact small-sided games on elite handball players     

Antonio Dello Iacono  Domenico Martone  Alessandro Moura Zagatto  Yoav Meckel  Mahmood Sindiani  Mirjana Milic 《Journal of sports sciences》2018,36(1):14-22

This study aimed to investigate the effect of contact (C-SSG) and no-contact (NC-SSG) handball small-sided games (SSGs) on motion patterns and physiological responses of elite handball players. Twelve male handball players performed 10 C-SSG and 10 NC-SSG while being monitored through the heart rate (HR) and rate of perceived exertion (RPE) as physiological responses and time-motion activities profile using video-match analysis. Both game conditions resulted in similar HR responses (P > 0.05), but the NC-SSG led to a higher RPE scores. The time-motion activity analysis featured NC-SSG with a greater amount of walking (855.6 ± 25.1 vs. 690.6 ± 35.2 m) and backward movements (187.5 ± 12.3 vs. 142.5 ± 8.7 m) combined with fast running (232.3 ± 8.5 vs. 159.7 ± 5.7 m) and sprinting (79.5 ± 4.7 vs. 39.7 ± 3.7 m) activities (P < 0.001). Conversely, C-SSG had a higher percentage of jogging and sideway movements associated with greater frequency of jumping (0.87 ± 0.09 vs. 0.31 ± 0.06 nr) and physical contact (1.82 ± 0.55 vs. 0.25 ± 0.03 nr) events (P < 0.001). No between-regimen differences were found for the number of throws (P = 0.745). In addition, the RPE was significantly correlated with fast running relative distances (r = 0.909, P < 0.001) and sprinting relative distances (r = 0.939, P < 0.001). In conclusion, this investigation showed that both C-SSG and NC-SSG in team handball can effectively represent specifically oriented exercises, according to the sport-task and the performance demands.  相似文献   

Swimming and peak bone mineral density: A systematic review and meta-analysis     

Alejandro Gomez-Bruton  Jesús Montero-Marín  Alejandro González-Agüero  Alba Gómez-Cabello  Javier García-Campayo  Luis A. Moreno 《Journal of sports sciences》2018,36(4):365-377

This meta-analysis aims to determine the effects of regular swimming on bone mineral density (BMD) in young adults (18–30 years). A systematic search was performed in Pubmed, SPORTDiscus and the Cochrane Library from the earliest possible year to March 2016. Swimmers were compared to non-athletic controls (CG) and to high-impact athletes (HIGH). Effect sizes with the Hedges g in random effects models were developed. Fourteen studies met the inclusion criteria and were included in the meta-analyses. Swimmers presented similar BMD values to CG in whole-body (g = ?0.20; P = 0.251), femoral neck (g = ?0.05; P = 0.818) and lumbar spine (g = 0.18; P = 0.492); and lower BMD in the whole-body (g = ?1.21; P < 0.001), femoral neck (g = ?1.51; P < 0.001) and lumbar spine (g = ?0.84; P = 0.017) than the HIGH. For the whole-body differences, the higher the latitude the smaller the differences between swimmers and HIGH (B = 0.10; P = 0.001). For the femoral neck differences, age also seemed to reduce the differences between groups (B = 0.19; P = 0.020). Young adult swimmers present similar BMD values than CG and lower values than HIGH.  相似文献   

Activity profile of top-class association football referees in relation to performance in selected physical tests     

Javier Mallo  José-María García-Aranda  Bart Gilis  Werner Helsen 《Journal of sports sciences》2013,31(7):805-813

Abstract

The aims of the present study were (1) to analyse the physical demands of top-class referees and (2) to compare their official FIFA fitness test results with physical performance during a match. The work rate profiles of 11 international referees were assessed during 12 competitive matches at the 2003 FIFA Under-17 World Cup and then analysed using a bi-dimensional photogrammetric video analysis system based on direct lineal transformation (DLT) algorithms. In the first 15 min of matches, the referees were more active, performing more high-intensity exercise (P < 0.01) than in the first 15 min of the second half. During the second half of matches, the referees covered a shorter distance (P < 0.01), spent more time standing still (P < 0.05), and covered less ground cruising (P < 0.05), sprinting (P < 0.05), and moving backwards (P < 0.001) than in the first half. Also in the second 45 min, the distance of referees from infringements increased (P < 0.05) in the left attacking zone of the filed. There was also a decrease (P < 0.05) in performance in the period following the most high-intensity activity, compared with the mean for the 90 min. Time spent performing high-intensity activities during a match was not related to performance in the 12-min run (r ² = 0.30; P < 0.05), the 200-m sprint (r ² = 0.05; P < 0.05), or the 50-m sprint (r ² = 0.001; P < 0.05). The results of this study show that: (1) top-class referees experienced fatigue at different stages of the match, and (2) the typical field tests used by FIFA (two 50-m and 200-m sprints, followed by a 12-min run) are not correlated with match activities.  相似文献   

An investigation into turn-away among information technology professionals in Brazil     

Eduardo Ramos  Luiz Antonio Joia 《The Journal of High Technology Management Research》2013,24(1):30-41

Two important problems have been observed fairly frequently among information technology (IT) professionals, namely turn-over – where the IT professional moves to another company but still remains in the IT sector – and turn-away, in which the IT professional abandons the area in order to occupy a position in a different area, either in the same company or in another, sometimes assuming a managerial function. Few research papers were found with respect to the latter phenomenon. Based on that, the main thrust of this work is to understand how and why IT professionals in Brazil abandon their area, identifying typical characteristics in their career transition. Thus, from a literature review about career development and the analysis of the data collected, eight research hypotheses were developed in order to be analyzed by the researchers. A multiple case study method with several units of analysis was applied in two large companies in Brazil. In-depth interviews were conducted with IT professionals who had migrated to other areas within their organizations, they being considered the unit of analysis. The results accrued from this research reveal that IT professionals in Brazil need to have more growth opportunities than either their companies have been able to offer them or it is possible to offer within the technical arena.  相似文献