Modelling and Simulation of the Power Take-Off System for a Hinge-Barge Wave-Energy Converter

The McCabe Wave Pump (MWP) has possibilities for the conversion of wave energy into electrical energy and the production of potable water. However, in order to optimise the dynamics and operation of this device in the face of a wide variety of sea conditions, a number of important control issues must be addressed. The first step, which is addressed in this paper, is the production of a dynamical model of the MWP, which can provide a basis for both control design and simulation. Since the power take-off (PTO) system provides the main damping in the system, the paper places particular emphasis on the PTO model and how it couples to the main rig dynamics. The control problem formulation is also briefly addressed

Modelling and Simulation of the Power Take-Off System for a Hinge-Barge Wave-Energy Converter

The McCabe Wave Pump (MWP) has possibilities for the conversion of wave energy into electrical energy and the production of potable water. However, in order to optimise the dynamics and operation of this device in the face of a wide variety of sea conditions, a number of important control issues must be addressed. The first step, which is addressed in this paper, is the production of a dynamical model of the MWP, which can provide a basis for both control design and simulation. Since the power take-off (PTO) system provides the main damping in the system, the paper places particular emphasis on the PTO model and how it couples to the main rig dynamics. The control problem formulation is also briefly addressed

Modelling and Simulation of the Power Take-Off System for a Hinge-Barge Wave-Energy Converter

The McCabe Wave Pump (MWP) has possibilities for the conversion of wave energy into electrical energy and the production of potable water. However, in order to optimise the dynamics and operation of this device in the face of a wide variety of sea conditions, a number of important control issues must be addressed. The first step, which is addressed in this paper, is the production of a dynamical model of the MWP, which can provide a basis for both control design and simulation. Since the power take-off (PTO) system provides the main damping in the system, the paper places particular emphasis on the PTO model and how it couples to the main rig dynamics. The control problem formulation is also briefly addressed

The Prevalence of Menstrual Cycle Disorders and Menstrual Cycle-Related Symptoms in Female Athletes: A Systematic Literature Review

Background: Menstrual cycle (MC) disorders and MC-related symptoms can have debilitating effects on the health and performance of female athletes. As the participation of women in sports continues to increase, understanding the prevalence of a range of MC disorders and MC-related symptoms may guide preventive strategies to protect the health and optimise the performance of female athletes. Objective: To examine the prevalence of MC disorders and MC-related symptoms among female athletes who are not using hormonal contraceptives and evaluate the assessment methods used to identify MC disorders and MC-related symptoms. Methods: This systematic review was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). Six databases were searched until September 2022 for all original research that reported the prevalence of MC disorders and/or MC-related symptoms in athletes not using hormonal contraceptives, which included the definitions of the MC disorders examined, and the assessment methods used. MC disorders included amenorrhoea, anovulation, dysmenorrhoea, heavy menstrual bleeding (HMB), luteal phase deficiency (LPD), oligomenorrhoea, premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD). MC-related symptoms included any affective and physical symptoms related to the MC that do not cause significant personal, interpersonal or functional impairment. The prevalence data across eligible studies were combined, and all studies were qualitatively synthesised to evaluate the assessment methods and tools used to identify MC disorders and MC-related symptoms. The methodological quality of studies was assessed using a modified Downs and Black checklist. Results: Sixty studies involving 6380 athletes were included. A wide range of prevalence was observed for all types of MC disorders, with a dearth of data on anovulation and LPD. Based on pooled data, dysmenorrhoea (32.3%; range 7.8–85.6%) was the most prevalent MC disorder. Studies reporting MC-related symptoms mostly examined the premenstrual and menstruation phases, where affective symptoms appeared more prevalent than physical symptoms. A larger proportion of athletes reported symptoms during the initial days of menstruation compared with the premenstrual phase. MC disorders and MC-related symptoms were retrospectively assessed using self-report methods in 90.0% of studies. Most studies (76.7%) in this review were graded as moderate quality. Discussion: MC disorders and MC-related symptoms are commonplace among female athletes, warranting further research examining their impact on performance and preventive/management strategies to optimise athlete health. To increase the quality of future studies, researchers should adopt standardised definitions of MC disorders and assessment methods such as a combination of calendar counting, urinary ovulation tests and a mid-luteal phase serum progesterone measurement when assessing menstrual function. Similarly, standardised diagnostic criteria should be used when examining MC disorders such as HMB, PMS and PMDD. Practically, implementing prospective cycle monitoring that includes ovulation testing, mid-luteal blood sampling (where feasible) and symptom logging throughout the MC could support athletes and practitioners to promptly identify and manage MC disorders and/or MC-related symptoms. Trial Registration: This review has been registered in the PROSPERO database (CRD42021268757)

Resisted sled sprint kinematics: The acute effect of load and sporting population

In this study, we assessed the acute kinematic effects of different sled load conditions (unloaded and at 10%, 20%, 30% decrement from maximum velocity (Vdec)) in different sporting populations. It is well-known that an athlete’s kinematics change with increasing sled load. However, to our knowledge, the relationship between the different loads in resisted sled sprinting (RSS) and kinematic characteristics is unknown. Thirty-three athletes (sprinters n = 10; team sport athletes n = 23) performed a familiarization session (day 1), and 12 sprints at different loads (day 2) over a distance of 40 m. Sprint time and average velocity were measured. Sagittal-plane high-speed video data was recorded for early acceleration and maximum velocity phase and joint angles computed. Loading introduced significant changes to hip, knee, ankle, and trunk angle for touch-down and toe-off for the acceleration and maximum velocity phase (p < 0.05). Knee, hip, and ankle angles became more flexed with increasing load for all groups and trunk lean increased linearly with increasing loading conditions. The results of this study provide coaches with important information that may influence how RSS is employed as a training tool to improve sprint performance for acceleration and maximal velocity running and that prescription may not change based on sporting population, as there were only minimal differences observed between groups. The trunk lean increase was related to the heavy loads and appeared to prevent athletes to reach mechanics that were truly reflective of maximum velocity sprinting. Lighter loads seem to be more adequate to not provoke changes in maxV kinematics. However, heavy loading extended the distance over which it is possible to train acceleration

On twin prime power Hadamard matrices

In this paper, we show that exactly one Hadamard matrix constructed using the twin prime power method is cocyclic. We achieve this by showing that the action of the automorphism group of a Hadamard matrix developed from a difference set induces a 2-transitive action on the rows of the matrix or is intransitive. We then use Ito’s classification of Hadamard matrices with 2-transitive automorphism groups to derive a necessary condition on the order of a cocyclic Hadamard matrix developed from a difference set. This work answers a research problem posed by K.J. Horadam, and exhibits the first known infinite family of Hadamard matrices which are not cocyclic