Deltastream is an on-going project carried by Tidal Energy Limited since almost twenty years. It is a tidal energy converter with a triangular shape and one turbine on each tower. It has gone through many evolutions of design but a first prototype will be installed in the end of 2014 at Ramsey Sound. The deployment and recovery operations will be carried out with a single lift point through a heavy lift frame. Two issues have to be tackled during the operation: the rate of flooding of the ballasts and the tension on the lift crane cable. The most favourable sea state must be found in order to minimise the crane cable tension as well as the best inlets and outlets configuration for the ballasts system. In order to tackle those issues, preliminary analytical work was conducted on the demonstrator to assess the stability during the flooding process. A scaled model was designed and built in order to be tested in a wave-towing tank. The results from the tests highlight that the deployment and the recovery operations are safe for both the barge and Deltastream for the range of wave conditions tested in the tank. However, the sea state has an important impact on the proceeding of the operations, especially the period of the waves.

Accelerometers are devices that have been recently used to assess the performance of weightlifters in training. This case study used vertical acceleration data to assess multiple snatch attempts in a single lifter during a training session. The lifter exhibited variability in a number of measures, including peak acceleration and peak velocity. The measures calculated from the acceleration-time data did not show consistent trends between made and missed lifts. More work is needed identify variables of interest for snatch performance.

Several methods have been used in the scientific literature to study the weightlifting pull. Broadly, these methods are used to measure kinematic or kinetic variables exhibited by the lifter, the barbell, or the lifter-barbell system. However, there is an apparent disconnect between weightlifting research and coaching practice that may reduce the perceived benefits of technique analysis among coaches and present some challenges for coaches who seek to incorporate technique analysis into their coaching practice. Differences and trends in the technique of competitive weightlifting performances are apparent from the available literature. However, there are also gaps in the literature due to infrequent analyses that are limited to narrow subgroups of the weightlifting population. Therefore, the purposes of this dissertation were to 1) update to the scientific knowledge of weightlifting technique and performance, 2) improve coaches’ ability to conduct and interpret technique analysis, and 3) enhance transferability of weightlifting in training to improve sport performance. A review of methods used to evaluate the weightlifting pull provides some practical guidance for coaches on the application and interpretation of weightlifting technique analysis. Video analysis is recommended as the most practicable method for coaches to implement technique analysis themselves. Methods used to study 319 lifts by women and men from two major international competitions demonstrate the feasibility and usefulness of video analysis as an inexpensive, time-efficient, and user-friendly method for coaches to conduct reliable technique analysis. The results of this dissertation suggest that a variety of techniques can be used to achieve international weightlifting success and provide some evidence of changes in weightlifting technique since at least the mid-1980’s. These results also indicate that a stereotypical technique profile among elite international weightlifters does not exist, which further support the notion that strength is a primary determinant of weightlifting ability.

Les cœurs de réacteur à neutrons rapides refroidi au sodium (RNR-Na ) sont constitués d’assemblages combustibles disposés selon un réseau hexagonal régulier, compact en régime de fonctionnement nominal.Sous l’effet de l’irradiation et de la température, les assemblages sont amenés à se déformer axialement et radialement.Les objectifs de cette thèse sont la compréhension des phénomènes neutroniques intervenant lors d’une telle déformation du cœur, l’impact sur la conception ainsi que la mise au point de schémas de calcul neutroniques déterministes innovants aptes à en évaluer l’amplitude.La première partie de ces travaux est dédiée au développement d’une modélisation analytique des causes de variations de réactivité lors de la déformation du cœur. Cette analyse a permis d’identifier à la fois les causes de ces variations de réactivité et l’impact du déplacement des assemblages en fonction de leurs directions et de leurs positions dans le cœur.Un premier schéma neutronique basé sur la méthode de projection de maillage a été conçu et développé à l’aide des codes ERANOS (BISTRO, H3D et VARIANT) et du solveur SNATCH Le deuxième schéma conçu se base sur la transformation géométrique du maillage de calcul : le maillage est modifié en fonction du champ des déformations des assemblages. Cette fonctionnalité a été implémentée pour le solveur SNATCH, initialement prévu pour la résolution de l’équation de Boltzmann pour de mailles régulières.Enfin un modèle itératif basé sur la méthode de projection de maillage a été mis en place afin de déterminer les champs de déformations les plus réactifs en fonction de l’énergie mécanique fournie au cœur dans sa configuration nominale. / The fuel assemblies of SFR cores (sodium fast reactors) are normally arranged in hexagonal regular lattices, whose compactness is ensured in nominal operating conditions by thermal expansion of assemblies pads disposed on the six assembly wrapper faces.During the reactor operations, thermal expansion phenomena and irradiation creep phenomena occur and they cause the fuel assemblies to bow and to deform both radially and axially.The main goal of this PhD is the understanding of the neutronic aspects and phenomena occurring in case of core and lattice deformations, as much as the design and implementation of deterministic neutronic calculation schemes and methods in order to evaluate the consequences for the core design activities and the safety analysis.The first part of this work is focused on the development of an analytical model with the purpose to identify the neutronic phenomena that are the main contributors to the reactivity changes induced by lattice and core deformations.A first scheme based on the spatial mesh projection method has been conceived and implemented for the ERANOS codes (BISTRO, H3D and VARIANT) and to the SNATCH solver.The second calculation scheme propose is based on mesh deformation: the computing mesh is deformed as a function of the assembly displacement field. This methodology has been implemented for the solver SNATCH, which normally allows the Boltzmann equation to be solved for a regular mesh. Finally, an iterative method has been developed in order to fulfill an a-priori estimation of the maximal reactivity insertion as a function of the postulated mechanical energy provided to the core, as much as the deformation causing it.

Preparing for a national weightlifting championship: A case series. J Strength Cond Res XX(X): 000–000, 2019—This study aimed to characterize psychological, physiological, and performance changes of a high-level female (24.5 years; 53.8 ± 0.3 kg; 155.4 cm) and male (25.8 years; 92.7 ± 1.2 kg; 189 cm) weightlifter over 28 weeks while preparing for a national championship. Body mass, hydration, psychological inventories, serum biomarkers, vastus lateralis muscle cross-sectional area (CSA), and squat jump (SJ) performance were assessed weekly beginning 11 weeks from the competition date. Weightlifting performance goals were met for the female athlete (actual total = 159 kg) but not for the male athlete (actual total = 292 kg). Reductions in vastus lateralis CSA possibly took place the week leading into competition for both athletes. Both athletes reported positive recovery-stress states on the day of competition relative to baseline values. Fluctuations between steroid hormone concentrations and inflammatory markers were unpredictable and inconsistent for both athletes throughout the training program. Unloaded SJ height and rate of force development were the highest on competition day for both athletes. Based on these findings, it is possible for high-level male and female weightlifters to achieve and maintain peak preparedness 3–4 days before competition following a 1-week overreach and 3-week exponential taper, where training volume-load is reduced by half and intensity maintained or slightly increased relative to pretaper values. Furthermore, the short recovery and stress scale and SJ testing seem to be useful tools for sport scientists and coaches when monitoring high-level weightlifters preparing for competition.

The purposes of the study were to track weightlifters' barbell acceleration with a portable accelerometer over three training sessions to examine test–retest reliability and to compare peak barbell acceleration at different training intensities. Twelve nationally ranked weightlifters volunteered for this study. The portable accelerometer was attached to the right side of the barbell to measure barbell resultant acceleration during the snatch lift at a sampling frequency of 100 Hz. The data were collected over three training sessions at intensity levels of 80%, 85%, and 90% of one repetition maximum. The data were analyzed using intra-class correlation coefficients (ICCs) for the three training sessions and one-way repeated measure ANOVA to compare the difference in peak barbell acceleration at three intensities. Results showed that the device was highly reliable with an ICC of 0.88 and 95% confidence interval of 0.81–0.93. There were significant differences in peak barbell acceleration at various lifting intensities, indicating a decline of the acceleration as the mass of the barbell became heavier. The portable accelerometer seems useful in measuring barbell acceleration data, which can be analyzed in future studies to monitor a weightlifter's performance in a practical setting instead of testing at a laboratory.

Excerpt:The purpose of this article is to present and discuss the phases of the pull that precede the power position, as well as present some suggestions for how to coach these positions...

The purpose of this thesis was to observe psychological, physiological, and performance changes to determine when two high-level weightlifters were peaked for a major competition. We addressed this purpose by conducting a two-part case study series with one USA international level female and one USA national level male weightlifter. Both athletes were considered to be peaked on competition day. The results support our hypothesis that jumping performance would be peaked on competition day corresponding with an increased recovery and decreased stress state. However, contrary to our hypothesis, each athlete exhibited small decreases in muscle size leading into the competition relative to baseline values. Further, changes in inflammatory markers were inconsistent for each athlete and were not reduced as hypothesized. Based on our findings, this investigation supports the use of overreaching and tapering for individual strength-power athletes providing insight into underlying psychological and physiological basis for observed changes in performance.

The search for new solutions for the generation of energy is becoming more and more important for our future. Big arguments and disagreements on e.g. the questions of gas transport or the dependence on energy supplied by other countries raise demands on the development of new forms of alternative energy resources. Wave power is one of the main sources of renewable energy due to the high power density stored in ocean waves. Nevertheless, the dynamic forces of waves are so large that serious questions popped up on how to design a system which could work even in an unfavourable wave climate or could at least retain working capabilities after big storms without significant damages. This thesis studies the reliability of the mechanical parts of a linear direct driven permanent magnet generator. The results of offshore experiment where strain gauge sensors instrumented on the capsule and the inner framework structure are presented. Stress estimation analyses using strain gauges are carried out. A method for measuring forces and moments in the mechanical structure of the WEC is developed. Evaluation of the lateral force acting on the outer structure is a key factor for the design and construction of the WEC. A method for the measurement of the lateral force acting on the capsule has been developed. A study of the inclination angle between the Wave Energy Converter and the floating buoy has been carried out. The aim of this work is to contribute to the development of wave energy conversion system, and especially to the estimation of structural loads which are important for the survivability of the system under hard sea states. This work is a step that may influence future design of wave energy devices in terms of material aspect, survivability in a hard wave climate and cost-effective renewable energies.

Monitoring tests are commonly used to assess weightlifter’s preparedness for competition. Although various monitoring tests have been used, it is not clear which test is the strongest indicator of weightlifting performance. Therefore, the purpose of this study was to (1) determine the relationships between vertical jump, isometric mid-thigh pull (IMTP) and weightlifting performance; and (2) compare vertical jumps to IMTP as monitoring tests of weightlifting performance in a large cohort of male and female weightlifters. Methods: Fifty-two competitive weightlifters (31 males, 21 females) participated in squat and countermovement jump testing (SJ, CMJ), and IMTP testing performed on force plates. All laboratory testing data was correlated to a recent competition where the athletes had attempted to peak. Results: Squat jump height (SJH) was the strongest correlate for men and women with the Sinclair Total (r = 0.686, p ≤ 0.01; r = 0.487, p ≤ 0.05, respectively) compared to countermovement jump height (r = 0.642, p ≤ 0.01; r = 0.413, p = 0.063), IMTP peak force allometrically scaled to body mass (r = 0.542, p ≤ 0.01; r = −0.044, p = 0.851) and rate of force development at 200 ms (r = 0.066, p = 0.723; r = 0.086, p = 0.711), respectively. Further, SJH was a stronger correlate of relative weightlifting performance compared to IMTP peak force in females (p = 0.042), but not male weightlifters (p = 0.191). Conclusions: Although CMJ and IMTP are still considered strong indicators of weightlifting performance, SJH appears to be the most indicative measure of weightlifting performance across a wide-range of performance levels. Thus, SJH can be used as a reliable measure to monitor weightlifting performance in male and female weightlifters.