Numerical and experimental study of the parametric rolling of a fisihing vessel in regular head waves

The dynamic behaviour of a fishing vessel in waves is studied in order to reveal its parametric rolling characteristics. This paper presents experimental and numerical results in longitudinal regular waves. The experimental results are compared against the results of a time-domain non-linear strip theory model of ship motions in six degrees-of-freedom. These results contribute to the validation of the parametric rolling prediction method, so that it can be used as an assessment tool to evaluate both the susceptibility and severity of occurrence of parametric rolling at the early design stage of these types of vessels.

Stability Analysis of a Run-of-River Diversion Hydropower Plant With Surge Tank And Spillway in the Head Pond

Run-of-river hydropower plants usually lack significant storage capacity; therefore, the more adequate control strategy would consist of keeping a constant water level at the intake pond in order to harness the maximum amount of energy from the river flow or to reduce the surface flooded in the head pond. In this paper, a standard PI control system of a run-of-river diversion hydropower plant with surge tank and a spillway in the head pond that evacuates part of the river flow plant is studied. A stability analysis based on the Routh-Hurwitz criterion is carried out and a practical criterion for tuning the gains of the PI controller is proposed. Conclusions about the head pond and surge tank areas are drawn from the stability analysis. Finally, this criterion is applied to a real hydropower plant in design state; the importance of considering the spillway dimensions and turbine characteristic curves for adequate tuning of the controller gains is highlighted

Signal-to-noise ratio of the MEG signal after preprocessing

Background Magnetoencephalography (MEG) provides a direct measure of brain activity with high combined spatiotemporal resolution. Preprocessing is necessary to reduce contributions from environmental interference and biological noise. New method The effect on the signal-to-noise ratio of different preprocessing techniques is evaluated. The signal-to-noise ratio (SNR) was defined as the ratio between the mean signal amplitude (evoked field) and the standard error of the mean over trials. Results Recordings from 26 subjects obtained during and event-related visual paradigm with an Elekta MEG scanner were employed. Two methods were considered as first-step noise reduction: Signal Space Separation and temporal Signal Space Separation, which decompose the signal into components with origin inside and outside the head. Both algorithm increased the SNR by approximately 100%. Epoch-based methods, aimed at identifying and rejecting epochs containing eye blinks, muscular artifacts and sensor jumps provided an SNR improvement of 5–10%. Decomposition methods evaluated were independent component analysis (ICA) and second-order blind identification (SOBI). The increase in SNR was of about 36% with ICA and 33% with SOBI. Comparison with existing methods No previous systematic evaluation of the effect of the typical preprocessing steps in the SNR of the MEG signal has been performed. Conclusions The application of either SSS or tSSS is mandatory in Elekta systems. No significant differences were found between the two. While epoch-based methods have been routinely applied the less often considered decomposition methods were clearly superior and therefore their use seems advisable.

Preliminary mineralogy and ore petrology of the intermediate-sulfidation pallancata deposit, Ayacucho, Peru

Se investiga la compleja mineralogía del Yacimiento de Pallancata (6º productor de plata del mundo) y se establecen las condiciones de formación (P.T) basadas en la petrología de las menas comparada con los datos de mineralogía experimental y en la petrografía y microtermometría de inclusiones fluídas en la ganga silicatada, resultando un depósito típicamente caracterizado como epitermal de sulfuración intermedia.ABSTRACT:Pallancata is a world-class intermediate-sulfidation epithermal deposit, hosted by upper Miocene volcanics of the south-central Peruvian Andes in a sinuous N70ºW, ∼75º SW strike-slip structure, with wide (up to 35 m) pull-apart dilation zones related to bends of the vein strike. The structural evolution of the vein from earlier brecciation to later open space infill resembles the Shila Paula district (Chauvet et al. 2006). Fluid inclusion petrography and microthermometry show that ore deposition is related to protracted boiling of very diluted, mainly meteoric fluids, starting at 250–260 ºC, under ∼300 m hydrostatic head. The mineralogical-petrological study reveals a complex sequence of mineralization (eight stages) and mineral reactions consistent with Ag2S enrichment or Sb2S3 depletion, or both, during cooling over the temperature range 250–200 ºC: pyrite, sphalerite, galena, miargyrite, pyrargyrite-proustite, chalcopyrite, polybasite-pearceite, argentite (now acanthite), and Au–Ag alloy (“electrum”). This Ag2S enrichment and Sb2S3depletion during cooling may be explained by decay of a Ag-rich galena precursor at deeper levels (Pb2S2–AgSbS2 solid solution), which rapidly becomes unstable with decreasing temperature, producing residual (stoichiometric) PbS and more mobile Ag and Sb sulfide phases, which migrated upward and laterally away from the thermal core of the system. The core is still undisclosed by mining works, but the available geochemical evidence (logAg/log Pb ratios decreasing at depth) is consistent with this interpretation, implying a deeper potential resource. Data from sulfide geothermometry, based on mineral equilibria, document the thermal evolution of the system below 200 ºC (stephanite, uytenbogaardtite, jalpaite, stromeyerite, mckinstryite, among others). The end of the most productive stages (3, 4, and 5) is marked by the precipitation of stephanite at temperatures below 197 ± 5 ºC, but precipitation of residual silver continues through the waning stages of the hydrothermal system down to <93.3 ºC (stromeyerite) or in a supergene redistribution (stage 8, acanthite II).

Analysis of the discharge capacity of radial-gated spillways using CFD and ANN - Oliana Dam case study.

The paper focuses on the analysis of radial-gated spillways, which is carried out by the solution of a numerical model based on the finite element method (FEM). The Oliana Dam is considered as a case study and the discharge capacity is predicted both by the application of a level-set-based free-surface solver and by the use of traditional empirical formulations. The results of the analysis are then used for training an artificial neural network to allow real-time predictions of the discharge in any situation of energy head and gate opening within the operation range of the reservoir. The comparison of the results obtained with the different methods shows that numerical models such as the FEM can be useful as a predictive tool for the analysis of the hydraulic performance of radial-gated spillways.

A novel motion tracking system for evaluation of functional rehabilitation of the upper limbs

Upper limb function impairment is one of the most common sequelae of central nervous system injury, especially in stroke patients and when spinal cord injury produces tetraplegia. Conventional assessment methods cannot provide objective evaluation of patient performance and the tiveness of therapies. The most common assessment tools are based on rating scales, which are inefficient when measuring small changes and can yield subjective bias. In this study, we designed an inertial sensor-based monitoring system composed of five sensors to measure and analyze the complex movements of the upper limbs, which are common in activities of daily living. We developed a kinematic model with nine degrees of freedom to analyze upper limb and head movements in three dimensions. This system was then validated using a commercial optoelectronic system. These findings suggest that an inertial sensor-based motion tracking system can be used in patients who have upper limb impairment through data integration with a virtual reality-based neuroretation system.

Feasibility assessment of the interactive use of a Monte Carlo algorithm in treatment planning for intraoperative electron radiation therapy

This work analysed the feasibility of using a fast, customized Monte Carlo (MC) method to perform accurate computation of dose distributions during pre- and intraplanning of intraoperative electron radiation therapy (IOERT) procedures. The MC method that was implemented, which has been integrated into a specific innovative simulation and planning tool, is able to simulate the fate of thousands of particles per second, and it was the aim of this work to determine the level of interactivity that could be achieved. The planning workflow enabled calibration of the imaging and treatment equipment, as well as manipulation of the surgical frame and insertion of the protection shields around the organs at risk and other beam modifiers. In this way, the multidisciplinary team involved in IOERT has all the tools necessary to perform complex MC dosage simulations adapted to their equipment in an efficient and transparent way. To assess the accuracy and reliability of this MC technique, dose distributions for a monoenergetic source were compared with those obtained using a general-purpose software package used widely in medical physics applications. Once accuracy of the underlying simulator was confirmed, a clinical accelerator was modelled and experimental measurements in water were conducted. A comparison was made with the output from the simulator to identify the conditions under which accurate dose estimations could be obtained in less than 3 min, which is the threshold imposed to allow for interactive use of the tool in treatment planning. Finally, a clinically relevant scenario, namely early-stage breast cancer treatment, was simulated with pre- and intraoperative volumes to verify that it was feasible to use the MC tool intraoperatively and to adjust dose delivery based on the simulation output, without compromising accuracy. The workflow provided a satisfactory model of the treatment head and the imaging system, enabling proper configuration of the treatment planning system and providing good accuracy in the dosage simulation.

Análisis cualitativo de la relación entrenador-deportista en etapas de formación en baloncesto = Qualitative analysis of the coach-athlete relationship in youth basketball

La relación entrenador-deportista estudia, dentro del ámbito de la psicología social en el deporte, la interacción de los comportamientos, sentimientos y emociones de ambos miembros de la pareja. Se entiende como un proceso en el que antecedentes como la edad, el género o las características esperadas en el otro condicionan el desarrollo de diferentes componentes, los cuales determinan la calidad de la relación, obteniéndose diferentes resultados tanto a nivel deportivo como personal. En la presente tesis se han estudiado 12 relaciones positivas entrenador-deportista en categorías de formación en baloncesto con el objetivo de conocer los condicionantes, componentes, estrategias y resultados de relaciones efectivas. Para ello, se ha realizado un estudio cualitativo, cuya muestra (N=24) se ha seleccionado de manera deliberada discriminando variables como el nivel deportivo del equipo, las características del entrenador, la duración y la calidad de la relación. Las 12 díadas participaban en el máximo nivel de su categoría, tenían una duración mínima de dos temporadas y fueron calificadas como positivas por los entrenadores principales. La investigación se ha llevado a cabo desde la perspectiva holística del fenómeno, teniendo en cuenta tanto el punto de vista del entrenador como el del jugador. Para la recogida de datos se utilizó la entrevista semiestructurada y en profundidad. Los resultados señalan la necesidad de desarrollar estrategias que promuevan y mantengan relaciones de calidad en baloncesto, ya que éstas tienen un alto impacto en el progreso deportivo y personal de los jugadores jóvenes en baloncesto. Entre los condicionantes de la relación entrenador-deportista se ha percibido que las expectativas formadas en los primeros contactos pueden determinar la calidad de la relación. Por otro lado, los componentes dan lugar a resultados como el crecimiento a nivel personal por parte de los jugadores o un mayor rendimiento deportivo, producido en gran medida por la satisfacción y el bienestar psicológico tanto del entrenador como del jugador. Por último, los resultados indican la importancia de adecuar el comportamiento del entrenador a las características propias de los jugadores en cada categoría de formación. ABSTRACT The coach-athlete relationship studies, within the field of social psychology in sport, the interaction of behavior, feelings and emotions in both partners. It is understood as a process in which antecedents such as age, gender or expectations develop different components. The quality of the relationship is determined by these three elements, leading to different results in sport performance as in personal variables. This thesis examined 12 positive coach-athlete rapports in youth basketball teams in order to better understand the determinants, components, strategies and outcomes of effective relationships. A qualitative study has been carried out. The sample (N = 24) is selected deliberately discriminating variables such as the team’s sportive level, coach characteristics, duration and quality of the relationship. Twelve dyads participated at the highest level in its category, had a minimum of two seasons and were rated as positive by head coaches. The research was conducted from a holistic perspective of the phenomenon, taking into account the point of view of both the coach and the player. Indepth semi-structured interview was used for data collection. The results report the need to develop strategies to promote and maintain high quality relationships in basketball, because they have an important impact in sport and personal development of young basketball players. Expectations raised through different impression cues in the first contacts can determine the quality of the relationship. On the other hand, the components lead to results such as players’ personal growth or sport performance, largely produced by the satisfaction and psychological well being of both the coach and the player. Finally, the results indicate the importance of adapting the coach’s behavior to the characteristics of the different stages of young athletes’ development.