Improving Computational Efficiency in WEC Design: Spectral-Domain Modelling in Techno-Economic Optimization

Wave energy converter (WEC) optimization often underlines incremental and iterative approaches that result in suboptimal solutions, since all the elements that concur with a techno-economical evaluation are optimized separately due to computation constraints. A design process should rely on precise WEC models to ensure high result accuracy while minimizing the computational demand. These conflicting objectives can be addressed with non-linear time-domain models, known to be numerically accurate, and frequency-domain models due to their high computational efficiency. This work pursues the development of an all-encompassing optimization tool for a gyroscopic-type WEC called ISWEC that applies a new modelling technique named spectral-domain technique as a substitution to the complex time-domain model previously employed. In particular, the spectral-domain technique provides accurate and fast performance predictions of the ISWEC system and offers the possibility to model a hydraulic power take-off, not representable in the frequency domain. The article illustrates techno-economic trends associated with an early-stage design of the ISWEC in high-energy sea-sites, where the low-speed and high-torque profiles call for the use of hydraulic transmissions as opposed to the old electro-mechanical transmissions. The design tool proposed could facilitate the development of WEC technologies via efficient and accurate power assessment and via the possibility of carrying out advanced techno-economic optimisation that goes beyond linear models

How Widespread Are the “Young” Neurons of the Mammalian Brain?

After the discovery of adult neurogenesis (stem cell-driven production of new neuronal elements), it is conceivable to find young, undifferentiated neurons mixed with mature neurons in the neural networks of the adult mammalian brain. This “canonical” neurogenesis is restricted to small stem cell niches persisting from embryonic germinal layers, yet, the genesis of new neurons has also been reported in various parenchymal brain regions. Whichever the process involved, several populations of “young” neurons can be found at different locations of the brain. Across the years, further complexity emerged: (i) molecules of immaturity can also be expressed by non-dividing cells born during embryogenesis, then maintaining immature features later on; (ii) remarkable interspecies differences exist concerning the types, location, amount of undifferentiated neurons; (iii) re-expression of immaturity can occur in aging (dematuration). These twists are introducing a somewhat different definition of neurogenesis than normally assumed, in which our knowledge of the “young” neurons is less sharp. In this emerging complexity, there is a need for complete mapping of the different “types” of young neurons, considering their role in postnatal development, plasticity, functioning, and interspecies differences. Several important aspects are at stake: the possible role(s) that the young neurons may play in maintaining brain efficiency and in prevention/repair of neurological disorders; nonetheless, the correct translation of results obtained from laboratory rodents. Hence, the open question is: how many types of undifferentiated neurons do exist in the brain, and how widespread are they

Experimental investigation of the mooring system of a wave energy converter in operating and extreme wave conditions

A proper design of the mooring systems for Wave Energy Converters (WECs) requires an accurate investigation of both operating and extreme wave conditions. A careful analysis of these systems is required to design a mooring configuration that ensures station keeping, reliability, maintainability, and low costs, without affecting the WEC dynamics. In this context, an experimental campaign on a 1:20 scaled prototype of the ISWEC (Inertial Sea Wave Energy Converter), focusing on the influence of the mooring layout on loads in extreme wave conditions, is presented and discussed. Two mooring configurations composed of multiple slack catenaries with sub-surface buoys, with or without clump-weights, have been designed and investigated experimentally. Tests in regular, irregular, and extreme waves for a moored model of the ISWEC device have been performed at the University of Naples Federico II. The aim is to identify a mooring solution that could guarantee both correct operation of the device and load carrying in extreme sea conditions. Pitch motion and loads in the rotational joint have been considered as indicators of the device hydrodynamic behavior and mooring configuration impact on the WEC

Social media adoption in Italian firms. Opportunities and challenges for lagging regions

Social media are an important growth opportunity for firms, especially small-sized ones operating in peripheral and lagging regions. In this paper, we investigate not only whether firms are able to take this opportunity, but also if they are able to face the challenge of adopting social media at a professional level to obtain a significant economic impact, measured in terms of exporting activities. Exploring the Italian case, our empirical study indicates that smaller firms in lagging areas are more likely to adopt social media but at the same time less likely to use them at a professional level. This reflects poor strategic targets of social media adoption and lower probabilities of entering international markets

Using statistical analyses for improving rating methods for groundwater vulnerability in contamination maps

With the aim of developing procedures coping with the disadvantages and emphasising the advantages of existing rating methods and the use of statistical methods for assessing groundwater vulnerability, we propose to combine the two approaches to perform a groundwater vulnerability assessment in a study area in Italy. In the case study, located in an area of northern Italy with both urban and agricultural sectors, keeping the structure of the DRASTIC rating method, we used a spatial statistical approach to calibrate weights and ratings of a series of variables, potentially affecting groundwater vulnerability. In order to verify the effectiveness of these procedures, the results were compared to a non-modified approach and to the map resulting from the ‘‘Time–Input’’ method, highlighting the advantages that can be obtained, and defining the general limit of these applications. The revised method shows a more realistic distribution of vulnerability classes in accordance with the distribution of wells impacted by high nitrate concentration, demonstrating the importance of taking into account the specific hydrogeological conditions of the area

Specific factors influence the success of autologous and allogeneic hematopoietic stem cell transplantation

Successful hematopoietic stem cell transplantation (HSCT), both autologous and allogeneic, requires a rapid and durable engraftment, with neutrophil (>500/µL) and platelet (>20,000/µL) reconstitution. Factors influencing engraftment after autologous or allogeneic HSCT were investigated in 65 patients: 25 autologous peripheral stem cell transplantation (PBSCT) and 40 allogeneic bone marrow transplantation (BMT) patients. The major factor affecting engraftment was the graft source for HSCT. Neutrophil and platelet recovery were more rapid in autologous PBSCT than in allogeneic BMT [neutrophil occurring in median on day 10.00 (09.00/11.00) and 19.00 (16.00/23.00) and platelet on day 11.00 (10.00/13.00) and 21.00 (18.00/25.00), respectively; p < 0.0001]. The type of disease also affected engraftment, where multiple myeloma (MM) and lymphoma showed faster engraftment when compared with leukemia, syndrome myelodysplastic (SMD) and aplastic anemia (AA) and MM presented the best overall survival (OS) in a period of 12 months. Other factors included the drug used in the conditioning regimen (CR), where CBV, melphalan (M-200) and FluCy showed faster engraftment and M-200 presented the best OS, in a period of 12 months and age, where 50–59 years demonstrated faster engraftment. Sex did not influence neutrophil and platelet recovery

Energy-maximising model predictive control for a multi degree-of-freedom pendulum-based wave energy system

Renewable energy sources can be a solution for the recent pollution increasing scenario and the need for diversification of the energy market. Among such alternative sources,wave energy represents a viable solution, due to the its high power density and accessibility.Nonetheless, wave energy is still in phase of development, and a key stepping stone towards commercialisation is strongly linked to the availability of optimal control strategies for maximum energy harvesting. With its ability to handle system constraints and optimise power absorption directly, model predictive control (MPC) has gained popularity within the WEC community as a potential solution for the corresponding energy-maximising problem. In this study, an MPC strategy is developed for real-time control of the so-called PeWEC energy harvesting system,providing also a solution for the wave excitation estimation and forecasting problem, inherently required by the MPC controller to achieve optimal performance. Improved computational requirements are obtained via definition of a reduced control-oriented model, describing the dynamics of the system in a compact form. The performance of the proposed strategy is illustrated via a comprehensive numerical appraisal