This thesis proposes equations extending the Free Surface Actuator Disc Theory to yield drag forces and interference factors from a series of two porous discs in open channel flows. The new model includes blockage ratio and Froude number as independent variables, which are inferred in advance to yield a single solution in the prescribed domain. The theoretical extension is integrated with the Blade Element Theory in a Double Multiple Streamtube model (DMS) to predict axial loads and the performance of confined Darrieus turbines. The turbine thrust force influences the flow approaching the rotor. Hence, a momentum method is applied to solve the hydraulic transition in the channel, achieving the unknown inflow factor from the undisturbed flow imposed downstream. The upstream blockage ratio and Froude number are thus updated iteratively to adapt the DMS to subcritical applications. The DMS is corrected further to account for the energy losses due to mechanical struts and turbine shaft, flow curvature, turbine depth, and streamtube expansion. Sub-models from the literature are partly corrected to comply with the extended actuator disc model. The turbine model is validated with experimental data of a high-solidity cross-flow hydrokinetic turbine that was previously tested at increasing rotor speeds. Turbine arrays are investigated by integrating the previous turbine model with wake sub-models to predict the plant layout maximizing the array power. An assessment of multi-row plants shows that the array power improves with closely spaced turbines. In addition, highly spaced arrays allow a partial recovery of the available power to be exploited upstream by a new turbine array. The highest array power is predicted by simulations on different array layouts considering constant array blockage ratio and rotor solidity. Finally, assuming a long ideal channel, the deviation in the inflow depth is speculated to become asymptotic after many arrays, implying almost identical power conversion upstream.

This work is focused on the development of controllable suspension systems for heavy-duty vehicles, in particular for agricultural tractors. In this field the research activity is not complete, as confirmed by the lack of scientific literature and for the few examples of commercial application for this kind of vehicles present in the market. For off-highway vehicles the load conditions can vary considerably and have an effect on the dynamic behaviour of the vehicle. Moreover, in many cases (such as tractors in agriculture), only the front axle is provided with a suspension. Typical applications of suspensions in off-highway industry include the cabin suspension (known as secondary suspension system) and the front axle suspension (known as primary suspension system). Up to now, the performance improvements have been reached through new solutions developed for the secondary systems, while the primary systems are generally implemented with passive systems, due to economical motivations and their limited energy demand. Obviously, such technical solutions partially satisfy the system requirements. Moreover, during the past few years there has been an increasing demand in power capabilities, loads and driving speeds of heavy duty vehicles. Therefore, off-highway vehicle manufacturers have shown their interest in employing controllable suspension, assumed as a potential way to reach the desired dynamic performances. The main targets of this activity is the study of the dynamical behaviour of agricultural tractors and the design of a cost-effective controllable suspension, capable to adapt the tractor dynamical behaviour, under different operating conditions. This work is part of a collaboration between Dana Corp. and the University of Trento. The main objective consists in the acquisition of competence in relation to the dynamic control of the vehicle. In particular the development of mechatronic systems according to the Model Based Design approach and the rapid prototyping of control algorithms. On this purpose, a simulation and experimental system was developed, for the testing of suspension systems and control algorithms for primary suspension systems. The first part of the thesis investigates the state of the art of the scientific literature of suspension systems for heavy duty vehicles, referring to different technologies and control solutions. In particular, attention was focused on the analysis and experimental characterization of commercial applications for this kind of vehicles present in the market. In the second part of the thesis the design development of a hydro-pneumatic suspension system is presented. The design of the control algorithms is based on the development of different multibody models of the actual tractor, including the pitch motion of the sprung mass, the load transfer effects during braking and forward-reverse maneuvers and the non-linear dynamics of the system. For an advanced analysis, a novel thermo-hydraulic model of the hydraulic system has been implemented. Several damping controls are analyzed for the specific case study. Therefore, the most promising damping strategy is integrated with other control functions, namely a self-leveling control, an original control algorithm for the reduction of the pitch motion, an anti-impact system for the hydraulic actuator and an on-line adaptation scheme, which preserves an optimal damping ratio of the suspension, even against large variations in operating conditions. According to the system requirements, the control is firstly integrated with other functionalities, such as the calibration of the suspension set-points and the procedures for the lock of the suspension. Finally, in accordance to the industrial product development, the control scheme is redefined in a Finite State Machine, useful for the subsequent generation of the ECU (Electronic Control Unit) Embedded Code. The final section of this work presents the development of an industrial prototype of suspension system, composed of a hydraulic suspension unit and a controller (hardware and software units). The prototype is tested by using a suspension bench test and Rapid Prototyping Tools for testing real-time control systems. Conclusions and final remarks and are reported in the last section.

The research activity of this thesis deals with the modelling of mechanical systems and two applications are analyzed by means of the same approach to modelling process. The first application is about the wind energy conversion systems. The modelling activity aimed at representing the behaviour of wind turbines operating in turbulent wind in terms of power conversion performances. The characterization of the test site has been thoroughly presented. Firstly, the concepts and the state of the art of both power curve and turbulence have been examined in detail. Secondly, a model based on a steady instantaneous power curve has been developed starting from the Reynolds approach at turbulence and a procedure to estimate the steady power curve from experimental data has been presented. The model proposed has been used on experimental data collected at the Trento test site to small wind turbines. Finally the model has been validated on experimental data through the comparison on energy capture forecasting. The second application presented deals with the measurement of cylinder roundness by means of multi-point method. The purpose of the modelling activity was the representation of the measurement process of cylinders surface through multi sensor measurement systems. The model has been developed considering step by step the architecture of the measurement system. Firstly, the generic cylinder shape and axis has been modelled in a parametric way. Then the irregular motion during the measurement process has been modelled thanks to a few parameters and finally the sensor disposition and theirs error has been implemented in the model. The parametric model obtained has been used to demonstrate the importance of consider the positioning errors of the sensors and the motion of the cylinder in 3D domain. Finally a three point method for radius and motion reconstruction has been implemented in the model and same Monte Carlo simulation has been carried out to demonstrate the effect of 3D disturbances on shape reconstruction.