The main objective of this paper is to drive a rotary inverted pendulum by following a desired navigation instruction. This navigation is commanded by the user through a new electromagnetic device which is allowed to perturb the pendulum from its upright position. This apparatus consists of an electronic magnetic driving circuit to introduce commands and realized via two operated magnetic coils. So, the external programmed magnetic perturbation can be seen as external commandments. Therefore, the control problem statement is solved via a modified regulation control implementation, to maintain the pendulum on its upright position and giving free manipulation of the base of the rotary inverted pendulum. Hence, by using the corresponding H∞-linear matrix inequality technique, a static state controller is designed and tested experimentally so supporting our findings. 相似文献
In this paper, we propose a numerically robust blind equalization scheme to mitigate cochannel and intersymbol interferences and separate signals from a convolutive mixture in multiple-input multiple-output (MIMO) communication systems. The robustness of the proposed scheme is achieved through a particular dual-mode operation applied to a constant-modulus-based space-time algorithm that corrects phase rotations. In the first mode of operation, the consistency in the nonlinear estimates of the transmitted signals is ensured. In the second mode, the Euclidean norms of the equalizer coefficient vectors decrease along the iterations, which allows the algorithm to return to the first mode of operation, where the estimation of the transmitted signals really occurs. In particular, we apply this scheme to a multimodulus version of the multiuser Shalvi-Weinstein algorithm (MU-SWA). By means of a deterministic stability analysis assuming the persistence of excitation condition, we show that the dual-mode MU-SWA does not diverge. 相似文献
This study aimed to validate an English version of Basic Psychological Needs Support Questionnaire (BPNSQ) and the Basic Psychological Needs in Physical Education Scale (BPN-PE) in the physical education context. Participants included 453 students aged between 12 and 17 years. For the BPNSQ, the hypothesized three-factor solution displayed high interfactor correlations (rs > 1), and a follow-up analysis indicated that the items were represented by a single need-support factor. For the BPN-PE, hypothesized three-factor solution was supported. Both scales were found invariant across gender, and the nomological validity was also demonstrated through the associations between factors of both scales. This study provides initial support for the use of the BPN-PE to assess psychological need satisfaction within the physical education context among English-speaking adolescents. The hypothesized three-factor structure of the BPNSQ was not supported and more research is needed to evaluate the English version in the physical education context. 相似文献
The purposes of this study were: (a) to analyze the factors determining the quality of relationships between a novice physical education (PE) teacher and his students’ families and (b) understand the implications of these relationships for his professional identity. The data stemmed from detailed teacher’s diaries written by the participant throughout his first five years of teaching. The data analysis followed several rounds of cyclical inductive-deductive processes in order to identify and classify the patterns related to the aforementioned purposes. The results, presented in two sections, show two distinct sets of factors, which, respectively, had very different implications for the development of the teacher’s professional identity. On the one hand, in the first three years of teaching, there appeared 11 specific ‘struggle factors’ (6 socio-cultural and structural factors and 5 family prejudices toward PE) that threatened the teacher’s initial pedagogical passion and lead to a great deal of hesitation and discouragement on his part; on the other hand, in the fourth and fifth years, due to the teacher’s ongoing commitment and (self-)reflective practice, there emerged eight ‘success factors’ (one from the families and seven from the teacher) that transformed his previous discouragement into hope and self-confidence. Besides the detailed analysis of all these factors and their implications, some additional recommendations for PE teacher education programs and further research are provided. 相似文献
Background: School is one of the primary settings where non-gender conformer children and adolescents emerge as vulnerable groups at high risk of suffering violence and harassment. Within schooling contexts, embodied experiences in physical education (PE) may become particularly problematic for trans students. However, there is little research focusing on trans persons’s experiences in PE. The purpose of this paper is to gather memories and impressions of a group of adult trans persons on their experiences in secondary PE.
Theoretical framework: The concept of heteronormativity is used as a theoretical framework to provide insights and understanding to trans persons’s experiences in PE. It is used to characterize inequalities and hierarchies derived from the intersection of the dualistic logic of gender binarism with other social categories and ideologies. Heteronormative discourses also act regulating the way of looking at and over trans persons’ bodies, categorizing some of them as queer or abject.
Participants and methodology: Study is based on semi-structured interviews to nine participants (five trans women and four trans men) from 23 to 62 years of age. A thematic analysis was carried out in order to flexibly and directly identify interpretative patterns of meaning within data, as well as to open them to interpretative frameworks. The categories were grouped into four themes best gathering the experiences of participants in PE.
Results and discussion: (1) Hindering desired gender: In daily practices, participants felt in ‘the middle’ of activities, spaces and gender groups, experiencing aloofness, isolation and loneliness. Participants complained about the fact that they could not perform gender segregated activities with their desired gender group. PE teachers played an important role in supporting heteronormative system. (2) Preferences, aversions and opportunities: All participants experienced hegemonic forms of gender and sexuality linked to PE programme activities in different ways. For most trans boys, sport-based PE was their favourite subject, while trans girls found it particularly negative and demotivating. Exceptionally, some aesthetic and dance activities were recalled as nearly non-heterosexual practices. (3) Confronting transgression. Situations of stigmatization and bullying in PE were frequent as a result from situations in which gender norms were eventually transgressed. Teachers impeded any attempt of trans persons to overcome heteronormativity in PE lessons. (4) Intimacy struggles: Body intimacy was crucial for participants. Different strategies were used for the search of intimacy. Changing rooms were the most problematic spaces for trans students in educative contexts. The worse trans participants felt about their bodies, the more uneasy they felt in these facilities.
Conclusions and final comments: Heteronormative contexts strongly determined trans persons’ experiences in PE. Trans participants, especially those not performing gender conforming practices, were abjectified in PE lessons. This situation generated multiple forms of exclusion and rejection, as well as episodes of harassment. However, some practices counteracted the dominance of the heteronormative system, showing their potential to destabilize this ideology in PE. 相似文献
Background: Student-Centered Inquiry as Curriculum (SCIC) is an activist approach [Oliver, K. L., and H. A. Oesterreich. 2013. Student-Centered Inquiry as Curriculum as a Model for Field-Based Teacher Education. Journal of Curriculum Studies 45 (3): 394–417. doi:10.1080/00220272.2012.719550] inspired by years of research with youth. It was designed as a means of listening and responding to youth in order to better facilitate students’ interest, motivation, and learning in physical education settings. While we have a strong and growing body of activist research with youth in physical education, SCIC as a specific approach to working with youth is in its infancy; thus, there is a need to further explore the challenges teachers/researchers face learning to use this approach to teaching.
Purpose: This study explores how educators, in different contexts, learn to use an activist approach called SCIC, in order to better facilitate students’ interest, motivation, and learning in physical education and physical activity settings.
Research setting and participants: Participants included a university professor, a college instructor, a postdoctoral student, a doctoral student, and a pre-service teacher. Data were collected between January and May 2016.
Data collection and analysis: Data collection included weekly field notes and debriefings following observations, teacher artifacts, weekly collaborative group meetings, and two individual interviews per teaching participant.
Discussion and conclusions: The main challenge that emerged was learning how to move from a theoretical understanding of student-centered pedagogy to the practice of student-centered pedagogy. Specifically, the amount of time that was necessary to build a foundation that allowed for student and teacher understanding, respect, and comfort, negotiating teacher and student assumptions that were embedded in the status quo of physical education (PE), and the struggle to gather and use meaningful data to guide pedagogical decisions. We negotiated these challenges through our professional learning community whereby we worked to all be able to see and name what was happening in our individual classes and collectively planned what was needed to move forward through these challenges. 相似文献
The main purpose of this study was to compare the effect of the constant load and self-paced exercise with similar total work on autonomic control after endurance exercise. Ten physically active men were submitted to (i) a maximal incremental exercise test, (ii) a 4-km cycling time trial (4-km TT), and (iii) a constant workload test with identical total external work performed at 4-km TT. Gas exchange was measured throughout the tests, while blood lactate, heart rate, and heart rate variability (HRV) were measured during the passive recovery. Power output measured at the last lap (i.e. 3600–4000?m) of 4-km TT (316?±?89?W) was statistically higher than power output measured at the end of the constant workload exercise (211?±?42?W). The 4-km TT produced higher values of blood lactate concentration (8.8?±?2.1?mmol?L?1) than the constant workload test (7.8?±?2.1?mmol?L?1). The heart rate recovery measured at 60?s (constant workload: 37?±?7?bpm; 4-km TT: 30?±?6) and 120?s (constant workload: 57?±?9?bpm; 4-km TT: 51?±?9?bpm) were higher in the constant workload than in the self-paced exercise. The HRV (i.e. RMSSD30s) was statistically higher in the constant load exercise measured at 120, 420, 450, 480, 540, and 570?s than the self-paced exercise. These findings suggest that the autonomic control responses were dependent of the endurance exercise modalities, with parasympathetic activity being delayed after self-paced exercise, as evidenced by post-exercise heart rate indices. 相似文献
This study aimed to determine the effect of different percentages of body weight support (BWS) on spatiotemporal step characteristics during running. 26 endurance runners (age: 37 ± 9 years) completed a running treadmill protocol consisting of 6 different conditions (BWS combinations: 0–50%), with velocity maintained at 12 km/h. Each condition lasted 1 minute. Step angle, ground contact time (CT), flight time (FT), step length (SL) and frequency (SF), and duration of phases during stance time (phase1: initial contact; phase2: midstance; phase3: propulsion) were measured for every step during the test using a photoelectric cell system. Compared with the baseline condition (100% BW), FT was longer, CT was shorter, SL was longer, SF was lower, and the step angle was higher with each increase in BWS (p < 0.05). Also, some changes were observed in the duration of phases during stance time: phase1 did not experience changes across experimental conditions (p = 0.096), phase2 decreased and phase3 increased as BW was supported (p < 0.05). These results indicate that as BW was supported, runners showed longer FT and SL, shorter CT, lower SF, and greater step angle as well as some changes in the phases during the ground contact. Therefore, this study highlights the effect of different percentages of BWS on spatiotemporal parameters. 相似文献
Cardiorespiratory fitness (CRF) is associated with health benefits in children, improving cardiac morphology, cardiovascular disease risk factors, and biological outcomes. This study aimed to examine the substitution effects of displaying a fixed duration of sedentary time with a fixed duration of physical activity (PA) at different intensities on children’s CRF. A total of 315 children (136 boys) were assessed (age: 10.6 ± 0.6 years old). Outcomes at baseline and follow-up (16-months) were CRF determined using a maximal cycle test and sedentary time and PA measured with accelerometers. Data were analysed by isotemporal substitution analyses estimating the effect of reallocating 30 min/day of sedentary time by light (LPA), moderate (MPA) and vigorous physical activity (VPA) on CRF. VPA was positively and significantly associated with CRF cross-sectional (β = 0.026, p < 0.001) and prospectively (β = 0.010, p < 0.001). Reallocating 30 min/day of sedentary time into VPA was positively cross-sectionally (β = 0.780, p < 0.001) and prospectively (β = 0.303, p < 0.05) associated with CRF. Conversely, relocating 30-minutes of sedentary time into 30 minutes of LPA and MPA was not associated with CRF. These results suggest that reallocating an equal amount of time from sedentary into VPA is cross-sectional and prospectively associated with a favourable CRF. 相似文献
Digital libraries (DLs) are complex information systems which can present changes in their structure, content, and services. These complexities and dynamics make system maintenance a non-trivial task, since it requires periodical evaluation of the different DL components. Generally, these evaluations are customized per system and are performed only when problems occur and administrator intervention is required. This work aims to change the situation. We present 5SQual, a tool which provides ways to perform automatic and configurable evaluations of some of the most important DL components, among them, digital objects, metadata, and services. The tool implements diverse numeric indicators that are associated with eight quality dimensions described in the 5S quality model. Its generic architecture was developed to be applicable to various DLs and scenarios. In sum, the main contributions of this work include: (i) the design and implementation of 5SQual, a tool that validates a theoretical DL quality model; (ii) the demonstration of the applicability of the tool in several usage scenarios; and (iii) the evaluation (with usability specialists) of its graphical interface specially designed to guide the configuration of 5SQual evaluations. We also present the results of interviews conducted with administrators of real DLs regarding their expectations and opinions about 5SQual. 相似文献
