Design methods for mobility

Composite materials are increasingly used in those fields where it is necessary to achieve the requirements of lightweight and high mechanical properties. Even though their high specific strength which get these materials very attractive, especially for the transport field, there are several critical issues that still limit their application in primary structures. Among these, dynamic loading conditions play a critical role because they can significantly lower their residual strength. This paper aims to investigate experimentally the structural response of a 25 mm thick Omega composite structure under different impact loading conditions. The investigated test article consists of E-glass fibres (40% volume fraction) reinforced polyester matrix. The structure is covered by a HELIOPOL 1401 M AGC W 11 gelcoat layer and it has been impacted through a drop mass of 3.94 kg, dropped from heights of 50 mm, 75 mm, 100 mm, 150 mm, 200 mm, 250 mm, 350 mm and 500 mm.

Keywords: Composite , Fibreglass , Impact behaviour , Mechanical testing

Cryomodules (CM) represents edge-frontier assemblies in particle physics research field. The road transportation of CM is a critical phase during which the structures can be subjected to significant dynamic loads. It is therefore necessary to design a Transportation Tool (TT) equipped with an appropriate suspension system. This work describes the approach adopted for the design of the TT for the CM PIP-II SSR1 (Proton Improvement Plan-II – Single Spoke Resonators 1), which is firstly introduced in the CM research field. Initially a Finite Element (FE) model was developed, considering the main sub-assemblies of the CM. However, this model was not suitable for the design of the TT due to the high computational burden. For this reason the model was exported as a Modal Neutral File and imported into a MultiBody software (MB) where the remaining components were modeled as concentrated stiffnesses or rigid bodies. The MB model thus obtained has drastically reduced the calculation time, proving to be fundamental in the TT iterative design phase, which involves the use of Helical Isolators (HI) performing the function of mechanical filters. To validate the effectiveness of TT in reducing dynamic loads, a 3D acceleration profile measured during the transport of a similar cryomodule (Linear Coherent Light Source II, LCLS-II) was used. Furthermore, the results of the MB model were used to perform the structural verification of some critical components of the CM.

Keywords: Cryomodule transportation , Mechanical filter , Reduced order modeling , Suspension system , Vibration isolation

In recent years, driving simulators have been widely used by automotive manufacturers and researchers in human-in-the-loop experiments, because they can reduce time and prototyping costs, and provide unlimited parametrization, more safety, and higher repeatability. Simulators play an important role in studies about driver behavior in operating conditions or with unstable vehicles. The aim of the research is to study the effects that the force feedback (f.f.b.), provided to steering wheel by a lane-keeping-assist (LKA) system, has on a driver's response in simulators. The steering's force feedback system is tested by reproducing the conditions of criticality of the LKA system in order to minimize the distance required to recover the driving stability as a function of set f.f.b. intensity and speed. The results, obtained in three specific criticality conditions, show that the behaviour of the LKA system, reproduced in the simulator, is not immediately understood by the driver and, sometimes, it is in opposition with the interventions performed by the driver to ensure driving safety. The results also compare the performance of the subjects, either overall and classified into subgroups, with reference to the perception of the LKA system, evaluated by means of a questionnaire. The proposed experimental methodology is to be regarded as a contribution for the integration of acceptance tests in the evaluation of automation systems.

Keywords: Driving simulator , Lane keeping assist , Steering wheel torque

Transdisciplinarity is characterising numerous research areas, in which natural sciences are integrated with technical and social sciences, requiring mixed methodologies for achieving full sustainability. However, there is a lack of engineering methods and design tools able to effectively integrate the analysis of human performance and social impacts with technical issues during product and process design. In this context, digital manufacturing tools and virtual simulation technologies can be validly used to create interactive digital mock-ups where human-system interaction during manufacturing operations can be simulated to support product and process design. The paper proposes a mixed reality (MR) set-up to support human-centred product and process design, where systems and humans interacting with them are monitored and digitalised to easily evaluate the human-machine interaction, with the scope to have feedback for design optimisation. Such an approach is defined as trans disciplinary since it merges technical design issues and human perspectives to design products on the basis of effective human performance, with the goal to early detect design criticalities and improve the overall system design. Industrial use cases have been developed to demonstrate the validity of the proposed approach to support human-centred design of a tractor. Results have demonstrated potential improvements, in terms of time saving for design review and workers' training, reduction of physical prototypes for design validation, reduction of late design and engineering changes, reduction of ergonomic issues, and global positive impact on time-to-market.

Keywords: human factors , human-centered design , transdisciplinary engineering , Virtual manufacturing , virtual reality (VR)

Modern MBTs (Main Battle Tank) are extremely expensive. Many outdated MBTs and other armored vehicles, often lacking the required armor protection, are still kept in depots. It is now convenient to upgrade them to optionally unmanned weapons by adding a humanoid driver, and a robotic arm as a loader. Sensors, an optional automatic driving system, a control and communication suite would complete the transformation. The main armament and secondary armament may be also changed or upgraded. The off-the-shelf huge electronic equipment can be installed wireless inside the hull. The old crew compartment may be spoiled of all the human related parts. Only the driver seat may be kept in order to leave the capability to remove the humanoid, robotized driver and reinstate the human one. This upgrade should also include a diagnostic system for the vehicle, the sensors and the additional systems to reduce the maintenance burden. An additional, specialized, lightweight armor suite should be focused to protect the mobilization system, the robots, the control and the communication system. This second part of the paper introduces a few options to convert the Leopard 1 MBT to an optionally piloted UMBT (Unmanned Main Battle Tank). A first, minimal step, is just the automation of the original tank. In a second step, the weight is reduced by installing a smaller 60mm cannon with a lighter, but more numerous ammunition storage. A third step increases the firepower by installing on the main turret an automated turret with a 12.7 or 30mm cannon with an optional additional 7.62 machinegun. It is also highly advisable to add an APU (Auxiliary Power Unit) and a battery to reduce IR (infrared) signature, improve main engine life and reduce maintenance.

Keywords: Automated turret , Leopard 1 , MBT , UCV , UMBT , Update

Modern MBTs (Main Battle Tanks) last more than 30 years. During this period, they will be periodically upgraded in any aspect except the basic structure. Even the main armor is becoming an upgraded accessory that depends on the nature of the threat. The main armament may be also changed or upgraded. The huge electronic equipment is the most upgraded part. The crew compartment may be upgraded in internal armor (for example for spalling), interfaces (optics, displays, commands), safety and protection devices (fire detection and suppression, ejection seats..). This continuous upgrade process should be included in the design of new vehicle, than can be modular for these mid-life upgrades. The vehicle is designed by adding items to the crew compartment and to the mobilization system. As an example, this first part introduces a few options to retrofit the ARIETE MBT. The retrofit cannot be reduced to engine and armor upgrade. A reasoned step approach is outlined in this paper. The first minimal step is based on an active armor and an HMD (Helmet Mounted Display) visual system. The weight increase is compensated by reducing road wheels weight. A second step increases firepower by installing on the main turret an automated turret with an automatic small cannon and a machinegun. The weight increase is compensated by limiting the internal ammunition storage of the main cannon to the anti-tank ones. A third step converts the turret internal ammunition storage into an automatic reloading system. In this way, the crew is reduced from 4 to 3. A fourth step increases crew safety by relocating the driver in the turret and by installing ejection seats. Solutions to reduce ground pressure and to increase the effective “power” available by replacing the final-drives and adding two electric motors on the front sprockets are also briefly examined. It is also highly advisable to add an APU (Auxiliary Power Unit) to reduce IR (infrared) signature, improve main engine life and reduce maintenance.

Keywords: ARIETE , automated turret , MBT , power , updated

Aluminum alloy properties are hugely influenced by temperatures and stress gradients. In piston engines, temperatures vary slowly when compared to operating pressure and stress. Therefore, averaging the temperature values is a valid assumption. This paper compares the experimental head temperatures of a Rolls-Royce-Merlin-XX-head with the ones of a NACA paper on a very similar Merlin-Packard-V-1650-7. This experimental method in based on residual hardness measurement on a head of a RR Merlin that crashed in Italy during WWII. The first part is to define the “working life” in hours of the engine. A few samples from a “cool” part of the head give the initial “thermally intact” hardness. Then the hardness of a few samples from a known temperature part is measured. In our case, it is the part of the head that is directly exposed to coolant. The time interval that gives a residual hardness equal to the one of the part of the head that is directly exposed to coolant gives the engine working life. For this purpose, a set of “cool part” samples are kept in at the maximum constant temperature of the coolant (135 degrees C). Then, a few specimens are kept at higher temperatures and are extracted from the oven at regular time intervals. The residual hardness is measured on these specimens. A further set of specimens is subjected to random thermal cycling to verify that the alloy hardness reduction is influenced by the time at high temperature and not by the thermal cycle history. In this way, a correlation between residual hardness and temperature is obtained for the specific engine alloy. It is then possible to measure the residual hardness of various points of the head and to obtain the maximum temperature reached in a specific point. In general, experimental tests have confirmed the cost-effectiveness of this approach. The NACA TM 2069 data and the ones measured with this method show an extremely good correlation. It is then possible to affirm that, also for the alloy used for the Merlin head, a modified Hiduminium RR50, this method of test is valid. Other positive tests were performed in the past with the much more common AlSi9 alloy used for the head of FIAT-1900jtd-8V automotive engine. The method of the residual hardness is old and has met several critics in the scientific community. This paper demonstrates that, for at least a few aluminum alloys, it is still valid. It is a very inexpensive method to evaluate temperatures in new engines using disposed units with a known load history and time. The results are precious to verify that the simulation results used in the head design led to reasonable results. In this way, the development time of new engines can be significantly reduced.

Keywords: head , measurement , piston engine , RR Merlin , temperature

The traditional method to draw automotive-turbocharger compressor maps is based on equivalent chocking conditions. In this way, theoretically, the compressor chocking conditions would be exactly evaluated with the new ambient (inlet) conditions. Unfortunately, chocking is not the worst working condition for turbochargers in piston engine applications. In addition, most available compressor maps are interpolated from very few CFD (Computational Fluid Dynamics) or experimental data. The result is that many designers convert the map into a “row” one with the volumetric max flow on the x-axis. However, even this approach has many limitations, since compressor performance depends on Mach and Re numbers. To clarify the concept, a simplified CFD method to draw the compressor map is introduced in this paper. An example, based on a true turbocharger, shows the limitations of most interpolated-maps that can be found in literature. This initial “raw” map has a volumetric flow rate in input (x-axis) and an absolute pressure ratio in output (yaxis). The islands of constant efficiency are then calculated by assuming that the diffuser has a unitary efficiency. Then a new method based on invariants is introduced to calculate the new map with different input ambient conditions [1]. It is based on the ambient sound speed. This method is then corrected in this paper by introducing more accurate values for density and Mach speed. In particular the correction due to the air moisture content is particularly critical. The new invariant map obtained in this way takes into account of variations in inlet air for Re and Mach numbers. The method is valid for automotive and aerospace applications up to 3,000m. Unfortunately, for higher altitudes, even this new method shows its limitations, with the necessity to recalculate the maps with CFD simulation. In fact, rarified air and lower inlet temperature reduce compressor performance in term of efficiency and compression ratio. On the contrary, turbines tend to transfer more power to the shaft. In this way, the compressor to turbine match is far from ideal.

Keywords: altitude , compressor , map , turbine , turbocharger , water content

With a foreseen life of more than 30 years, the future Main Battle Tanks (MBT) will face continuous upgrades in and will challenge ever-changing threats. The armament, the armor, the information and the communication suite will be upgraded/changed depending on the scenario and on the technology available. Like in moder cars, the huge hardware/software/sensors is the most changing package. This continuous upgrade should be included in the design of new vehicle, than should be conceived more as a modular, vehicle family than as a single vehicle. The new battle tank is closer to a car platform that is the base for a family of vehicles, in which a major revision of any single model should be performed every two years. The old option-less approach like the Ford T model, which remained in production from 1908 to 1927, belongs to the past. A very desirable requirement would be to host the new vehicle in the bay of the latest C130 for rapid deployment. Even if it is time to update the venerable C130 to something newer and more capable, the basic concept remains. The always-growing 100-ton pan-tank approach is becoming obsolete, along with the idea to add hardware to improve firepower, protection and battlefield effectiveness. This third part introduces a few concepts to design a new MBT or better, a new MBT family, in which a modular concept makes it possible to adapt the vehicle to a specific scenario and to update it with ease. Flexibility and update capability are the new key words. The old concept of the mobile bunker with tracks should be substituted by a hierarchical protection system. This approach is inherited from the attack helicopters. The best-protected part of the tank should be a very small crew compartment. It should be completely separated from the weapon compartment with the main and secondary armaments equipped with automatic loading systems. The NBC (Nuclear Bacteriological Chemical) air filtering system can then be reduced to serve only the humans. The crew should travel secured by safety belts and should be equipped with ejection seats. Air-bag should be considered to reduce the shock of a direct hit from APFSDS penetrator or other high energy threats. These seats are conceptually different from aircraft ones since they will assure a simple exit from the tank, not a true ejection. A multiengine-multimotor approach may be used for traction with two or more powered sprockets. The small powerpacks will occupy less room inside the vehicle. A drive by wire system with an enhanced stability and direction system should be implemented. The ground pressure should be kept well under 900 kPa. Tracks should be narrow and long to reduce power requirements. Only the frontal arc of the MBT should be protected with passive "direct kill" armor. The remaining part of the vehicle should rely on hard-kill active systems except for "light" automatic fire. Since armor is an accessory, it should be added to the basic MBT structure. The "adding" from the outside approach should be extended to as many items as possible to simplify maintenance, equipment and update. The basic vehicle structure is closer to the frame of an F1 car with all the parts and accessories added to it. Similarly to F1 racing cars, it can be made with lightweight materials and aircraft technologies, like Carbon Fiber Reinforced Plastic or aluminum alloy monocoque structure. Finally, an on-board electronic diagnosis system should be implemented to simplify maintenance and increase availability and reliability.

Keywords: Automated turret , Modular , New generation mbt , Upgradable

High altitude, airborne, wind-energy extraction-systems are the only true alternative to carbon and nuclear produced energy. Airborne Wind Turbines are very efficient due to the possibility to search the altitude with the nominal wind velocity. Winds are very stable and fast at altitudes from 4,000m (13,000ft)-11,000m (36,000ft). It is possible have many airborne generators near consumers in restricted airspace regions. In the first two parts, autogiro solutions demonstrated to be fully feasible but not economically convenient. This third part of the paper deals with the design of a mass-produced fixed wing system for power generation. A fixed wing drone with a minimal airframe was conceptually designed for this purpose. The power generated is 220 kW at 13,600ft (4.15 km) as in the first parts of this paper. 13,600ft (4.15 km) is statistically the best altitude for high power availability and reasonable tether length. The drone is a simplified, unmanned ultralight aircraft. Therefore, it has all the advantages of ultralights: the simplified design rules, the vast knowledge and the mass-produced commercial parts and subsystems. Ballistic parachutes are also available for emergency. As in the first two parts of this paper, the airborne system is tethered to transfer the electric energy to the national grid. On ultralight-generator deployment, the reversible electric generator works as a motor and the airborne generator flies as an aircraft. This UAV (Unmanned Aerial vehicle) can take off from a very short grass field due to the low wing loading. The UAVs unfolds and holds the tether up the required altitude. In the climbing phase, the tether powers the aircraft using the national grid electric power. Once the airplane reaches the operating position, as the nose is turned into the wind, the wind provides the lift and the propeller is reversed to windmill. In this way, it is possible to convert the electric motor into a generator. The autopilot keeps the airplane in the desired position. In nominal attitude and altitude (100km/h@4,150m-54kn@13,600ft), the rotor-generator outputs 0.22 MW. A preliminary design of a mass produced prototype is introduced in this paper with a cost per kWh competitive with fossil generated energy.

Keywords: Airborne wind turbine , Electric power generation , Fixed wing , Green energy , High altitude

In the last past years, computer-Aided technologies to improve existing products by widening the design space have been largely investigated. Topology optimization and generative design are two of the most representative technologies of such kind. This paper aims at investigating the use of generative design and topology optimization techniques to improve products whose design has not changed radically over the years. The product under investigation is a disk brake floating caliper that is the most common solution for commercial vehicles. In general, increasing the stiffness of the floating caliper while keeping its weight under control is desirable both from performance and fuel consumption point of view. The solution here proposed aims at exploiting two new ways to approach the engineering design process and evaluate which one is more suitable for problems of this kind. Starting from the original carrier shape, acquired with laser scanning, the two technologies have been applied on the same initial conditions. The initial design space volume corresponds to the acquired shape, the loads and the constraints for the simulation have been drawn reasonably to resemble the actual operating conditions. Keeping the input parameters constants, two different off-The-shelf software packages have been used to perform the computation and with the objective of maximizing the stiffness of the carrier while reducing its mass. The comparison and the improvements on the final designs have been drawn taken as reference to the original caliper..

With the observation of the gravitational wave event of August 17th 2017 the multi-messenger astronomy era has definitely begun. With the opening of this new panorama, it is necessary to have new instruments and a perfect coordination of the existing observatories. Crystal Eye is a detector aimed at the exploration of the electromagnetic counterpart of the gravitational waves. Such events generated by neutron stars' mergers are associated with gamma-ray bursts (GRB). At present, there are few instruments in orbit able to detect photons in the energy range going from tens of keV to few MeV. These instruments belong to two different old observation concepts: the all sky monitors (ASM) and the telescopes. The detector we propose is a crossover technology, the Crystal Eye: a wide field of view observatory in the energy range from 10 keV to 10 MeV with a pixelated structure. A pathfinder will be launched with Space RIDER in 2022. We here present the preliminary results of the characterization of the first pixel.

Keywords: Crystal Eye , Gamma-ray detector , GRB , LYSO , Multi-messenger astronomy , X-ray detector

Main target of this paper is to describe the conceptual design and the virtual prototyping phases of a new detector, named Crystal Eye, aimed at the exploration of the electromagnetic counterpart of the gravitational wave events. Such events generated by neutron stars collision (or mergers) are associated with γ-ray bursts. With its characteristics, Crystal Eye will provide the continuous exploration and monitoring of the Universe after a Gravitational Wave event with a better resolution than that of other detectors such as the Fermi Gamma-ray Burst Monitor (GBM). Thanks to its large field of view and its design, it has the potentiality to be the trigger for those present X-ray astronomy missions (Chandra, Swift, Integral XMM Newton) that are based on high angular resolution pointing experiment but that have unfortunately a very small field of view. An intense brainstorming phase, involving a team of physicians and engineers for the generation of concepts, started the design process. So, many preliminary sketches and CAD models were realized to well identify the main requirements of the new detector. Afterwards, considering the features and the constraints of the project, a refinement of the possible solutions among all the alternatives thought was performed, and three virtual prototypes were selected according to the Multi-Voting Method. Lastly, the AHP (Analytic Hierarchy Process) Multi Criteria decision making approach was considered to designate the best concept.

Keywords: AHP , Concept Design , Detector , Gravitational Wave , Mechanical Design , Multi-Voting method , X-rays

The aim of the research is to develop an azimuthing contra-rotating propeller for commercial applications with a power of 2000 kW. The thruster system is designed especially to be installed on high speed crafts (HSCs) for passenger transport with a cruising speed of about 35-40 knots. The topic is very useful because the azimuth thruster solutions currently do not find commercial applications in naval units for passenger transport. The latter are heavy, not very efficient from a hydrodynamic point of view and suitable for maximum cruising speed of about 18-20 knots. The study is interesting because among the advantages that these solutions provide are the possibility of transmitting very high torques and to guarantee a much longer life cycle. In more detail, the propulsion is realized by using a C-drive configuration, with a first mechanical transmission realized by using bevel gears mounted in a frame inside the hull, and a second transmission realized by bevel gears housed in a profiled hull at the lower end of a support structure. In the profiled hull will be installed the shafts of the propellers, in a contra-rotating configuration. In order to optimize the system before its industrial use, a close power loop test bench has been studied and designed to test high power transmissions. The test configuration allows to implement a back-to-back connection between two identical azimuthing contra-rotating propellers. Moreover, the particular test bench allows to size the electric motor simply based on the dissipated power by the kinematic mechanisms. Since the efficiency of these systems are very high, it is not necessary to use large electric motors, thus managing to contain the operating costs of the testing phase. The most significant disadvantage is the need to have two identical transmissions with consequent increase in installation costs. Through the back-to-back test bench it was possible to study the increase in efficiency compared to traditional systems.

Keywords: azimuthing contra-rotating propeller , CAD modeling , experimental test , finite element analysis , POD , Thruster

Nowadays, the quality assurance of aeronautical components is a very crucial issue. Diverse defects can be generated during composite material components manufacturing such as voids, delamination, cracks, etc. The identification of these defects requires the use of different types of inspection methods. In this paper, two diverse non-contact inspection techniques, i.e. a laser-based reverse engineering method and an ultrasonic testing procedure, are integrated to provide a complete quality assessment of carbon fibre reinforced polymer components for applications in the aeronautical field. A custom made software code was developed in order to create a user interface allowing for the visualization and analysis of the reverse engineering and ultrasonic information for the detection of geometrical and internal flaws of the component under inspection.

Keywords: Composite materials , Laser-based reverse engineering , Non-contact testing , Quality control , Ultrasonic non-destructive inspection

At present time the project of a naval vehicle, where with the word project we refer to all the process of design and manufacturing, especially when the vehicle offers special formal and performance characteristics, involves a number of operators that has been increasing considerably in recent decades, and this increased complexity can be correlated with dimensional and typological growth of many categories of ships. Simultaneously we are witnessing a complete new project approach, where the possibility given by the computer contribution to represent processes and results becomes crucial. The paper aims to investigate the consequences of this progress in the organization of the project and focuses on the innovative methodologies, bringing as an emblematic case the evolution of the hull study and the role of "planning matrix" that it also constitutes even on the graphic plane. The studio cases examined, which the reflections presented here refer to, are related to ships where the combination of performances and shapes takes on a particularly significant value: therefore, references are made to yachts and fast vehicles such as hydrofoils or catamarans. Finally, with special regards to Hydrofoils, the study will report a comparison made about the seakeeping and resistance of 2 different types of wings for hydrofoils, the comparison has been done at first step by using CFD calculations and then validated trough tank tests to show the validity of the results.

This paper focuses on the comparative assessment of comfort and discomfort (hereafter, (dis-)comfort) for aircraft seating. Subjective and objective data of seating (dis-)comfort were collected during an experiment involving 20 volunteers who tested 3 aircraft double-seats in upright and reclined position. In order to minimize experimental uncertainty due to well-known noise factors (i.e. patterns of discomfort during the work week and during the work day, order of evaluation, inter-individual differences), experimental trials were performed according to a crossover design. Statistical data analysis aimed mainly at investigating (dis-)comfort differences across seat conditions; gender-based differences in perceived discomfort on different body parts; effect of sitting duration on perceived discomfort on different body parts. The experimental results show that differences across seat conditions impacted differently on perceived discomfort depending on gender, body parts and sitting duration. No significant differences in perceived discomfort across gender were evident for the lightweight seat in both upright and reclined positions. On the contrary, for both baseline configurations, perceived discomfort at head and neck areas was higher for males than for females. For all seat conditions, participants experienced a significant worsening of perceived comfort over time at shoulders, back, sacrum and thighs and, in addition, at upper body area (i.e. neck, arm and forearm) and knees only for seats in reclined position.

Keywords: Aircraft seat , Discomfort index , Seating comfort , Seating discomfort

The spreading of high computational resources at very low costs led, over the years, to develop new numerical approaches to simulate the fluid surrounding a sail and to investigate the fluid–structure interaction. Most methods have concentrated on upwind sails, due to the difficulty of implementing downwind sailing configurations that present, usually, the problem of massive flow separation and large displacements of the sail under wind load. For these reasons, the problem of simulating the fluid–structure interaction (FSI) on downwind sails is still subject of intensive investigation. In this paper, a new weak coupled procedure between a RANS solver and a FEM one has been implemented to study the FSI problem in downwind sailing configurations. The proposed approach is based on the progressive increasing of the wind velocity until reaching the design speed. In this way, the structural load is also applied progressively, therefore, overcoming typical convergence difficulties due to the non-linearity of the problem. Simulations have been performed on an all-purpose fractional gennaker. The new proposed method has been also compared with a classic weak FSI approach. Comparable results have been obtained in terms of flying shape of the gennaker and fluid-dynamic loads. The most significant characteristic of the proposed procedure is the easiness to find a solution in a very robust way without convergence problem, and also the capability to reduce the simulation time with regard to the computational cost.

Keywords: Computational fluid dynamics , Finite element method , Fluid–structure interaction , Gennaker , Interactive sail design , Mainsail

Nowadays, more than in the past, marine industries are paying increasing attention to the environmental impact of ships and vessels. Several solutions have been studied and adopted with the final aim of reducing the exhaust gas emissions, mainly acting on the fuel consumption reduction. Within this scenario, the aim of this article is to investigate the energy performance and the fuel saving potential when employing a magnetic continuously variable transmission in a marine propulsion system. Such magnetic continuously variable transmission, considered among other possible continuously variable transmission designs since its torque capabilities are perfectly suitable for the application at hand, is employed in order to optimize the overall propulsion efficiency through an appropriate optimal variation of the reduction ratio as a function of the propeller loads. A secondary benefit, although not less important, is that the magnetic continuously variable transmission is an oil-free transmission that consequently offers a lower environmental impact as compared to traditional lubricated gearboxes. Owing to these considerations, in the article, the magnetic continuously variable transmission size is first selected on the basis of a simplified static model of the vessel. Subsequently, a dynamic mathematical model representing the overall drivetrain dynamic of the propulsion plant is developed, with the purpose of simulating the transmission behaviour during fast ship manoeuvres. Then, in order to test the effectiveness of the proposed design, a trawler is selected as a case study. This particular ship type has been chosen as it provides a variegated operative profile in terms of speed and required thrust, thus being a representative case of those ships in which a continuously variable transmission installation could effectively provide practical benefits. A quantitative analysis of the plant efficiency is finally provided and critically discussed.

Keywords: continuously variable transmission , fuel consumption , Marine propulsion plant , ship energy efficiency , time domain simulation

Elloboat is a tracked vehicle for launching and beaching of small boats and watercrafts, capable of operating in a wide range of operative conditions, here including rescue applications. This paper presents the vehicle architecture and discusses the main design issues. The effects of track dimensions on terrain compaction, bulldozing resistances and, consequently, on track sinkage are analyzed by means of the Bekker model. Obviously, track dimensions also influence the vehicle mass and size, leading to a complex engineering problem. Since vehicle speed and acceleration are limited, stability during locomotion can be assessed using a quasi-static approach, computing the longitudinal and lateral tipping angles for a given vehicle configuration and payload position, and imposing a proper limit to their minimum. Stability analysis can be exploited not only in the design phase, but also for the real-time evaluation of the actual margin of stability, so as to help the operator in the vehicle path/speed planning.

Keywords: Beaching , Bekker Theory , Launch , Small Boat , Tracked Vehicle , Watercraft