ISWEC Design Tool

ISWEC (Inertial Sea Wave Energy Converter) is a gyroscopic effect based wave power extraction device. The aim of this paper is to present a tool developed for the design process of this WEC. The main purpose of the software is to allow to the system engineer to compute the annual electrical productivity using a simplified model, taking into account several considerations such as system geometrical and electrical configurations, the hull properties or the installation site. To obtain this result, an automatic optimization of control parameters is implemented. A cost function is minimized under various system constraints (e.g. PTO torque and power, flywheel speed) and the absorbed power of the system is evaluated. Output of the software is the device productivity, along with considerations about structural loads, PTO utilization, floater and mass properties. The software will help the system engineer to take preliminary decisions and to verify the adaptability of this WEC to the considered sea site. The methodology here proposed can be easily generalised to other applications, especially in wave energy field, where severe constraints and time consuming simulations are common, and the use of a tool like this can reduce develop time, giving different information from the very start of the project

Microvascular endothelial cell spreading and proliferation on nanofibrous scaffolds by polymer blends with enhanced wettability

The objective of this study is elucidating the mechanisms by which the wettability of nanofibrous electrospun mats varies in polymer blends, and highlighting how this can play a pivotal role in enhancing the viability of cultured microvascular endothelial cells (EC). A functional microvascular network is essential for supplying bioengineered tissues with oxygen and nutrients while removing metabolic wastes. An in vitro pre-vascularization strategy consists of seeding EC on scaffolds, which in turn promotes cells infiltration, adhesion and functionality. We use electrospun poly-L-lactic acid (PLLA) and gelatin (Gel) as prototype materials for realizing nanofibrous scaffolds as bioartificial architectures to improve the proliferation and the functionality of human microvascular ECs (HMEC-1). HMEC-1 seeded on electrospun scaffolds adhere, remain viable, proliferate and positively express the endothelial cell marker CD31 particularly on blend PLLA/Gel fibers, which exhibit wettability enhanced with respect to both the constituent polymers, and are therefore especially promising constructs for promoting the formation of functional endothelial tissue. The wettability characteristics of the blend polymer fibrous scaffolds are modeled and discussed. These results can be valuable for the future design of pre-vascularized scaffolds with enhanced wettability properties for functional tissue engineered implants, with ECs able to form in perspective an effectively functioning vasculature upon implantation

Application of a Passive Control Technique to the ISWEC: Experimental Tests on a 1:8 Test Rig

In this work, we address the use of Hardware In the Loop test rig for renewable energy application. Such test rig is designed to evaluate the performances of the wave harvesting system called ISWEC. The ISWEC is a floating, slack-moored, gyroscopic Wave Energy Converter. The full-scale prototype has an electric-mechanical Power take-off (PTO) composed by a gearbox and a brushless torque motor. The system is torque controlled to keep the gyroscope in the desired position range and to obtain maximum productivity. In order to obtain this, two different control methods are under study: a proportional-derivative (PD) law and a passive control method. The PD control law regulates the torque on the PTO providing a stiffness term to recall the gyroscope in the vertical position and a damping term to extract power. In this configuration, the PTO performs the recall effect, resulting in an increase of the torque load. To overcome such problems, the use of an eccentric mass to provide the stiffness term is analyzed. The experimental tests demonstrate the reduction of the PTO torque, justifying the gap in the system productivity provided by the passive control as assessed with the numerical model

Scienza a voci

Dizionario biografico on line delle scienziate italiane dal Settecento al Novecento. http://scienzaa2voci.unibo.it (Accordo di programma per un progetto di ricerca "Scienza a due voci "fra Università di Bologna e il MIUR, progetto tuttora in corso)