Stabilization of positive constrained T–S fuzzy systems: Application to a Buck converter

This paper deals with the problem of constrained stability and tracking of Takagi–Sugeno (T–S) fuzzy positive systems. Linear programming (LP) is used to insert the constraints in the design phase while imposing positivity in closed-loop. The theoretical results are applied to the buck DC–DC converter which is widely used in the photovoltaic generators. Based on the simulation results success of the method is shown for this application.     

When do firms rely on their knowledge spillover recipients for guidance in exploring unfamiliar knowledge?

Knowledge spillover occurs when recipient firms combine the knowledge of an originating firm with other knowledge. When recipient firms combine the originating firm's knowledge with knowledge that is unfamiliar to the originating firm, the recipient firms potentially provide insight to the originating firm on the viability of exploring such knowledge. By mimicking its recipient firms, the originating firm reduces the challenge and uncertainty of exploring unfamiliar knowledge domains. We examine the exploration activities of 87 telecommunications equipment manufacturers over a ten-year time period. We argue that those firms that operate in competitive and dynamic market environments promoting conservative risk-taking behavior will value such uncertainty reduction more highly and thus rely to a greater extent on their recipient firms for guidance on where to explore for new expertise. In contrast, firms in high-growth market environments are more likely to look beyond the activities of recipient firms when exploring new technological domains and rely less on mimicking their recipient firms.     

Synchronization of discrete-time complex dynamical networks with interval time-varying delays via non-fragile controller with randomly occurring perturbation

This paper addresses synchronization problem for discrete-time complex dynamical networks with interval time-varying delays. In order to achieve the synchronization, a feedback controller subjected to randomly occurring perturbations will be considered. The randomly occurring perturbations are assumed to belong to the Binomial sequence. By constructing a suitable Lyapunov–Krasovskii functional, and utilizing reciprocally convex approach and Finsler?s lemma, the synchronization criteria for the networks are established in terms of linear matrix inequalities (LMIs) which can be easily solved by various effective optimization algorithms. The networks are represented by the use of Kronecker product technique. The effectiveness of the proposed methods will be verified via numerical examples.     

Investigation of the heat transfer of a non-Newtonian fluid flow in an axisymmetric channel with porous wall using Parameterized Perturbation Method (PPM)

In the present article Parameterized Perturbation Method (PPM) is used to obtain the solutions of momentum and heat transfer equations of non-Newtonian fluid flow in an axisymmetric channel with porous wall for turbine cooling applications. The validity of the results of PPM solution were verified by comparison with numerical results obtained using a fourth order Runge–Kutta method. These comparisons reveal that Parameterized Perturbation Method is a powerful approach for solving this problem. The analytical investigation is carried out for different governing parameters namely, Reynolds number, injection Reynolds number, Prandtl number and power law index. The results show that skin friction coefficient increases with increase of Reynolds number, especially at high Reynolds numbers. Also it can be found that Nusselt number has direct relationship with Reynolds number, Prandtl number and power law index.     

Evaluating the Responsiveness of Accelerometry to Detect Change in Physical Activity

The responsiveness to change of the Actical and ActiGraph accelerometers was assessed in children and adolescents. Participants (N = 208) aged 6 to 16 years completed two simulated free-living protocols, one with primarily light-to-moderate physical activity (PA) and one with mostly moderate-to-vigorous PA. Time in sedentary, light, moderate, and vigorous PA was estimated using 8 previously developed cut-points (4 for Actical and 4 for ActiGraph) and 5-sec, 15-sec, and 30-sec epochs. Accelerometer responsiveness for detecting differences in PA between protocols was assessed using standardized response means (SRMs). SRM values ≥.8 represented high responsiveness to change. Both accelerometers showed high responsiveness for all PA intensities (SRMs = 1.2–4.7 for Actical and 1.1–3.3 for ActiGraph). All cut-points and epoch lengths yielded high responsiveness, and choice of cut-points and epoch length had little effect on responsiveness. Thus, both the Actical and ActiGraph can detect change in PA in a simulated free-living setting, irrespective of cut-point selection or epoch length.     

Relationships between anthropometric measures and athletic performance,with special reference to repeated-sprint ability,in the Qatar national soccer team

Abstract

The aim of this study was to determine potential relationships between anthropometric parameters and athletic performance with special consideration to repeated-sprint ability (RSA). Sixteen players of the senior male Qatar national soccer team performed a series of anthropometric and physical tests including countermovement jumps without (CMJ) and with free arms (CMJwA), straight-line 20 m sprint, RSA (6 × 35 m with 10 s recovery) and incremental field test. Significant (P < 0.05) relationships occurred between muscle-to-bone ratio and both CMJs height (r ranging from 0.56 to 0.69) as well as with all RSA-related variables (r < –0.53 for sprinting times and r = 0.54 for maximal sprinting speed) with the exception of the sprint decrement score (S_dec). The sum of six skinfolds and adipose mass index were largely correlated with S_dec (r = 0.68, P < 0.01 and r = 0.55, P < 0.05, respectively) but not with total time (TT, r = 0.44 and 0.33, P > 0.05, respectively) or any standard athletic tests. Multiple regression analyses indicated that muscular cross-sectional area for mid-thigh, adipose index, straight-line 20 m time, maximal sprinting speed and CMJwA are the strongest predictors of S_dec (r² = 0.89) and TT (r² = 0.95) during our RSA test. In the Qatar national soccer team, players’ power-related qualities and RSA are associated with a high muscular profile and a low adiposity. This supports the relevance of explosive power for the soccer players and the larger importance of neuromuscular qualities determining the RSA.     

Indirekte Gesundheitseffekte des Unterrichtsprogramms HealthyPEP

Numerous studies have confirmed direct health effects of interventions with a physical activity component on students without providing sufficient information on the contents or the degree to which the programs have been carried out. The empirical evidence of the indirect health effects of physical education is weaker. In this article the focus is placed on the evaluation of the indirect health effects, such as the enhancement of physical activity and its psychological determinants (e.g. motivation, attitudes, self-efficacy and knowledge) of the health promotion program HealthyPEP, using a quasi-experimental design with 516 sixth grade students. When taking into account the contents of HealthyPEP and the degree of implementation, it was clear that the program had different effects on the two genders whereby girls evaluated HealthyPEP in a more positive way compared to boys. In girls, positive tendencies were observed on rational cognitive determinants (e.g. knowledge and attitudes towards sports). The contents of HealthyPEP must be further optimized in the future to achieve positive indirect health effects also on boys.     

Contextualizing the effects of childhood sexual abuse on adult self- and social functioning: an attachment theory perspective

OBJECTIVE: This retrospective survey study explored the hypothesis that multiple maltreatment and loss experiences in early childhood would interfere with the formation of secure attachments, creating (1) an increased vulnerability to childhood sexual abuse (CSA), and (2) adult problems in self- and social functioning. METHOD: Data were collected from 687 undergraduates on an urban, commuter campus. They were analyzed by means of between group (individuals with and without CSA histories) and within group (individuals with CSA histories) path analytic models. RESULTS: The number of maltreatment and loss experiences encountered in early childhood predicted greater CSA frequency in childhood and increased maltreatment in adulthood in the form of more frequent reports of sexual, physical, and emotional abuse. Childhood maltreatment and loss experiences also predicted poor adult self-functioning in the form of higher levels of depression and lower levels of self-esteem. Self-blame in response to CSA and maltreatment in adult relationships also predicted poorer adult self- and social functioning for individuals with CSA histories. CONCLUSIONS: Findings support both direct and mediational effects of childhood maltreatment and loss experiences on adult self- and social functioning and are consistent with predictions derived from attachment theory.