Design methods for mobility

This review explores a variety of techniques that utilize air injections beneath a vessel's hull to reduce drag and consequently improve energy efficiency. It focuses on the methodologies of microbubble drag reduction (MBDR), air layer drag reduction (ALDR), and air cavity drag reduction (ACDR), offering insights into their design, operational mechanisms, and potential applications. This review provides a detailed examination of the underlying principles of these technologies, incorporating a blend of experimental research, numerical simulations, and mathematical modelling to offer a comprehensive understanding. It references recent experimental data, highlighting how these findings corroborate with numerical simulations and are further explained through mathematical models. Conclusively, this review accentuates the transformative influence of air injection methods in drag reduction within the maritime industry, emphasizing their pivotal role in boosting operational efficiency, reducing environmental impact, and driving the evolution of naval design and transportation. Through a balanced and detailed analysis, this review provides a holistic view of the current state and future prospects of these innovative resistance reduction strategies.

Keywords: air cavity , air layer , air lubrication , CFD , drag reduction , microbubble , sustainability

The naval research and industry are facing with the significant challenge of ensuring carbon neutrality for the future of sustainable transportation. This imperative arises from the fundamental role that this sector occupies in global trade and the transportation of people. To achieve this goal, the use of green propulsions and alternative fuels play a central role, guaranteeing a significant reduction of ships global emissions and the respect of rules imposed in the Emission Control Areas (ECAs), therefore the preservation of the sea. If environmental awareness has been a reality for which efforts have been underway for years in land-based transportation, the same cannot be said for the maritime industry. For this reason, and with the aim of introducing innovative and more eco-compatible solutions, the paper presents the methodology used for the preliminary design of a 75-m Mega Yacht and sizing of the hybrid diesel-electric propulsion system equipped with hydrogen powered fuel cells and pressurized storage. As current technology does not support long-range sailing with full hydrogen propulsion, the hybrid propulsion was preferred. The configuration presented offers the flexibility of full electric sailing for short distances (up to 130 nautical miles) or to access protected areas, while also allowing traditional propulsion when hydrogen refuelling infrastructure is unavailable at ports or when faster sailing is required. The power unit consists of four FCs with a total power of 540 kW, two 180 kW electric motors combined with two 1765 kW thermal engines. The hydrogen storage area is composed of 105 cylinders with a total capacity of 21.3 m3 and a pressure of 350 bar, respecting the current regulations and guidelines for the use of hydrogen and pressurized explosive gases onboard. Furthermore, the IMO criteria were met to verify the feasibility of the idea.

Keywords: Fuel cell applications , Hybrid , Hydrogen , Maritime , Naval , Sustainable

In recent years, additive manufacturing has been expanding rapidly in several sectors, including marine, aerospace and civil, offering broad design freedom and environmental/ecological advantages for the production of fully functional products. Particularly in the biomedical area, interesting manufacturing methods have recently been developed for the customisation of orthotic devices by automating the acquisition process and 3D printing. Today, in the development of complex geometries, it is necessary to meet certain design specifications, such as mechanical strength, surface finish, light weight, breathability and aesthetic appearance, which can potentially be met by manufacturing with 3D printers. This research deals with the development and implementation of organic bioplastic compounds based on polylactic acid (PLA) and organic by-products for additive manufacturing applications of customised orthotic parts. PLA, filled with reinforcements and additives, can be used to produce durable and functional parts for improved structural performance. By studying specific orthotic cases with CAD-CAE techniques, its potential mechanical properties will be evaluated and compared to highlight its performance comparable or even superior to that of classical PLA. The proposed methodology reduces production costs and environmental impact. Thanks to the presence of reinforcements and additives, the new organic bioplastic compounds are more biodegradable, while improving some of the functionality and comfort requirements of customised orthoses.

Keywords: biodegradability , biomedical orthosis devices , mechanical properties characterization , Organic bio-composite filament , Reverse Engineering

As a class of compliant mechanisms that derive their motion from the deflection of flexible members, spherical compliant joints offer frictionless displacement, compactness, and improved precision compared to their rigid counterparts. Among these, tetra joints have gained significant attention in recent years. A novel approach for modeling and analyzing tetra joints, that is challenging due to their special geometry, is presented in this study. An efficient geometric model for streamlined tetra joint modeling, utilizing a Computer-Aided-Engineering (CAE) framework in COMSOL Multiphysics, is introduced. Through detailed discussions, the generation of tetra joint's geometry and the development of a parametric model are elucidated. Additionally, guidelines for constructing the finite element model of the joint and defining relevant boundary conditions are provided. To demonstrate the applicability of the proposed model, two critical parameters of tetra joints are analyzed: the vertical position of the remote center of rotation and the joint's height. The results highlight the significant influence of the vertical position of the remote center of rotation on the joint's mobility, indicating that proximity to the top face of the tetrahedron leads to increased rotation. Conversely, variations in the joint's height have a less pronounced effect on resulting rotations.

Keywords: Compliant Mechanisms , Parametric Model , Spherical Joint , Tetra Joint

The detection of surface defects is a critical activity for quality assurance of automotive products. Deep learning (DL) methods range among the most suitable tools to support this task. They allow the inspection system to learn how to detect surface defects on the basis of a series of sample images. However, most of the past studies regard laboratory experiments. This study demonstrates the actual integration of an inspection system into an industrial production plant to perform surface defect inspection operations on machined and unmachined areas of aluminium components for hybrid cars. The proposed DL method is practical for industry, where the number of available defect samples is low. Experimental results showed a True Positive Rate of 98%.

Keywords: artificial intelligence , deep learning , high-pressure die-casting , machine vision , quality control , surface defects

The global economy heavily relies on maritime commerce, commonly known as the “Blue Economy,” which involves the transportation of raw materials and products via maritime traffic and the utilization of marine resources, including oil, gas, and underwater mines. The importance of various infrastructures linked to the sea, such as fish farms, pipelines, underwater power and data cables, cannot be overstated as they have significant impacts on both local and global economies. Therefore, safeguarding these infrastructures against both symmetric and asymmetric threats is crucial to prevent disruptions to vital services and avoid negative impacts on the economy and quality of life. This book chapter presents an underwater access control system designed to monitor and prevent unauthorized access to port areas from the seaside to safeguard maritime infrastructures. The system consists of acoustic and magnetic barriers connected to a wireless communication network that can collect and transmit data to the infrastructure control centre. The system provides robust, dependable, and secure solutions for near real-time data transfer, enabling continuous monitoring and prompt response to potential threats. This chapter provides a detailed description of the system architecture and its primary components, focusing on the technological aspects and innovative solutions used to meet the proposed requirements.

Within the framework of the assisted systems for automotive applications, considerable research has been employed to monitoring the driver's attention level in order to assess the risk level of the driving scenario. In this context, physiological monitoring of the driver's condition has emerged as a relevant approach to enhance driving assistance without having an invasive approach. According to these premises, the authors have developed a driving assistance system capable to employ a dedicated bio-sensor for capture the driver's photoplethysmographic (PPG) signal, which is closely linked to their level of attention. This PPG signal is then processed by a dedicated deep learning architecture to reconstruct the driver's attention level. Meanwhile a separate automotive-grade intelligent vision-based system has been developed to quantify the risk level of the driving scenario by means of a video saliency analysis technique. The effectiveness of this comprehensive system has been validated through experimental results.

Keywords: ADAS , automotive , Deep Learning , risk assessment

The remarkable characteristics of polytetrafluoroethylene (PTFE) have made it one of the most widely used materials in various fields, especially in industry. PTFE has a low coefficient of friction, a high degree of anti-adhesive properties, excellent resistance to external agents, above all a high degree of resistance to low and high temperatures that guarantee long-lasting performance. In this research, a geometric dimensioning and tolerance (GD&T) and manufacturing methodology was presented to optimise the resistant torque in car doors hinges. The manufacturing technology of a PTFE-coated bronze bushing inserted with an FeZnNi pin inside the hinges of a car door was analysed and optimised. A predictive mathematical model was developed and validated with measurements using an appropriate experimental set-up created by the authors. Specifically, the experimental tests were performed by simulating and automating the rotation of the hinge, using software and electronic cards connected to an electric stepper motor; this made it possible to accurately assess the resistant torques due to assembly errors, tightening torques, geometric tolerances, etc. A correct assessment of the resistant torque and especially the friction torque is crucial, both at the design and production stages, to correctly calibrate the door drive loads (opening-closing), and to correctly predict the fatigue life of the components. Through the proposed methodology, the resistant torque was related to the correct manufacture and assembly of the hinge components.

Keywords: Bushing , FeZnNi pin , Friction torque , Geometric assembly tolerances , Hinges manufacturing , Polytetrafluoroethylene (PTFE)

The integration of automated vehicle (AV) technology in public transportation systems offers promising opportunities to improve the flexibility and safety of the traffic environment. However, user acceptance remains a critical challenge in the field of human-machine interaction for the effective deployment of shared autonomous vehicles (SAVs). This study presents a design framework aimed at enhancing user acceptance through human-machine interface (HMI) design tailored to SAVs. The framework is developed in adherence to relevant interaction design principles, following a systematic approach encompassing three key steps: analysis, synthesis, and evaluation. It integrates user acceptance factors into the design process, providing a structured method for designers. The framework was iteratively refined through interviews with three international domain experts; a focus group discussion with 10 researchers and professionals specializing in automotive interaction designers; and a workshop with 30 students and designers. The results demonstrate the framework's ability to guide the development of user-acceptable HMI solutions. The paper concludes by emphasizing the need for further exploration into how user acceptance factors evolve over time and how real-world testing can validate the framework's effectiveness in promoting user acceptance and satisfaction.

Keywords: design framework , human-machine interfaces , shared autonomous vehicles , user acceptance

Today, reducing vehicle energy consumption is a crucial topic. For electric vehicles, reducing energy consumption is essential to address some of the most critical issues associated with this type of vehicle, such as the limited range of electric powertrains and the long battery recharging times. To lower the environmental impact during the vehicle's use phase and reduce energy consumption, vehicle mass reduction (lightweighting) is an effective strategy. The objective of this work is to analyze the vehicle parameters that influence lightweighting outcomes on a real driving cycle, representative of the home-to-work travel in northern Italy. In particular, a previous work carried out on standard driving cycles is repeated in order to observe whether it is possible to draw the same conclusions regarding the variability in the lightweighting outcome. This study was conducted using two opposite vehicle models, a compact car and an N1 vehicle, simulated through a well-established vehicle simulation tool for energy consumption estimation. To conduct this analysis, several simulations with variable vehicle mass, and with different vehicle parameters, such as aerodynamics and rolling resistance, were performed to estimate energy consumption across a real-world driving cycle, acquired via GPS on board the vehicle during a home-to-work journey in northern Italy. This study reveals that even for the real driving cycle, as for the WLTC and US06 standards, the parameters that most influence the outcome of the lightening are the rolling resistance, the characteristics of the battery pack, the aerodynamic coefficients, and the efficiency of the transmission. Finally, the standard cycle that best fits with the real one considered in this study is the Artemis Urban Cycle.

Keywords: automotive , consumption analysis , energy consumption , energy reduction value (ERV) , fuel reduction value (FRV) , real data , real driving cycle , vehicle lightweighting

Suspension and steering design play a major role in ensuring the correct dynamic behavior of road vehicles. Passenger cars are especially demanding from this point of view: NVH and ride comfort requirements often collide with active safety-related requirements such as road holding in steady-state conditions and stability in transients. Driving pleasure is also important for market success, therefore accurate steering feedback and predictable handling properties are additional priorities. Since flexible bushings are used as interface between the suspension arms and the chassis, extra degrees-of-freedom make the design process a complex task. While the use of a multibody software is common practice in the industry, a dedicated computational tool can be more practical and straightforward, especially when undertaking the design of a new suspension concept ground-up. The paper presents a computational methodology for the design of an independent suspension with the associated kinematic and compliance attributes. Typical elastokinematic properties like toe, camber, wheelbase, and track variations versus tyre forces and moments can be computed by means of a dedicated software tool. A sort of validation was performed either by means of a comparison with a MathWorks Simscape® Multibody based model. Finally, a sensitivity analysis is given as an example. Computationally, the method proposed is intuitively based on the equilibrium equations. The nonlinear equations are then solved with Newton–Raphson algorithm. The method can be also optimized for computational efficiency and is thoroughly described so that the reader can easily replicate it in the desired programing environment. ìì

Keywords: computational kinematics and dynamics , computational mechanics , elasto-kinematics , nonlinear phenomena , vehicle suspension , vehicular dynamics

Global warming and air pollution are the main factors influencing international, national, and local strategies for the transition towards clean technologies to reduce polluting and climate-altering emissions. A further reduction of the latter can be achieved, with the same powertrain technology, by reducing vehicle consumption. One technique is to lighten the vehicle. The goal of this feasibility study is to act on the battery thermal management system to achieve vehicle lightweighting. Specifically, a sedan car with active-cooled batteries was considered as a reference case, and primary lightweighting was achieved through the use of passive cooling methods, i.e., air and Phase Change Material (PCM) cooling systems, followed by secondary lightweighting to re-establish the target range of the reference vehicle by downsizing the batteries. The air-cooled system leads to greater lightweighting, but its field of application is limited to vehicles operating in fleets; this obstacle can be overcome by using a PCM.

Keywords: Electric Vehicle; PCM (Phase Change Material) , Energy Consumption , Secondary Lightweighting , Traction Battery Thermal Management System , Vehicle Lightweighting

Since flexible bushings are used as the interface between the suspension arms and the chassis, the extra degrees of freedom make the design process a complex task. While the use of a multi-body model is common practice in the industry, a dedicated computational tool can be more practical and straightforward, especially when undertaking the design of a new suspension concept from the ground up. This paper presents a quasi-static method for calculating suspension compliance under the action of forces and moments, enabling real-time simulations. The algorithm proposed in this paper was devised with a threefold purpose: integrating elasto-kinematics into the kinematic design tool previously created by the authors, integrating real-time vehicle dynamics simulation, and overcoming the limitations of the traditional approach based on the superposition principle. Finally, a comparison of the proposed model with one based on the lookup-table and superposition principle is presented.

Keywords: Bushing , Compliance , Elasto-kinematics , Kinematics , Simulation , Suspension , Vehicle Dynamics

The safety of vessels at sea is crucial, given the potential presence of obstacles such as rocks, other vessels, or offshore structures. Impacts with such objects pose a significant risk to the integrity of ships and the safety of passengers. The present research activity explores safety in international nautical competitions, with a specific focus on races governed by the International Union of Motorboating (UIM). It analyzes the innovative design of the hull's sandwich construction of the XCAT racing catamaran, crucial for ensuring safety in the event of violent impacts, such as those from capsizing. The research activity involved four-point bending tests and impact tests to evaluate the mechanical performance and impact resistance of these sandwich specimens. Two types of sandwich structures were subjected to bending tests to determine their load-bearing capacity and to impact tests to assess their energy absorption characteristics. Through testing the effectiveness of structural innovations in enhancing the resilience of high-speed vessels is thus ensured, providing useful information for the development of theoretical and numerical prediction models.

Keywords: Four-point Bending Test , High-speed vessel , Impact Testing , Maritime Safety

This paper investigates the environmental impact and mechanical performance of two composite sandwich structures, named Series 1 and Series 2, used in high-performance racing boats. Mechanical tests, including four-point bending and drop impact tests, were performed. It was found on a general basis that Series 2 has higher load-bearing capacity and limited deflection. Series 1, which has a higher density, was able to absorb more impact energy but was more susceptible to damage. A Life Cycle Assessment (LCA) was conducted to evaluate the environmental impact associated with the materials, considering also the testing phase, which plays an important role in the life cycle of materials and structures for advanced marine applications. In addition, two performance indexes were introduced to correlate the mechanical and environmental properties of the analyzed materials. This study emphasizes the importance of considering the testing phase in LCA, as the energy-intensive nature of mechanical testing contributes significantly to the overall environmental impact. The introduced indexes allow for a more comprehensive understanding of the balance between mechanical performance and environmental sustainability. The findings suggest a trade-off between mechanical performance and sustainability, calling for further research into recyclable composites and greener manufacturing processes to balance these competing priorities.

Keywords: four-point bending test , high-speed vessel , impact testing , life cycle assessment , maritime safety

(1) Background: As cycling gains popularity as a mode of transportation, the frequency of accidents involving cyclists also rises. This has become a major concern for traffic safety, sustainability, and city planning. Identifying the risk factors that contribute to bicycle road accidents remains a significant challenge. This study aims to figure out which risk factors make some road segments more dangerous for cyclists than others. (2) Methods: This study introduces the use of a bicycle simulator to test different road segments involving thirty-nine participants. The impact of demographics and some risk factors related to infrastructure were analyzed in terms of their influence on the perceived level of risk through pre- and post-surveys. (3) Results: The findings showed that the bicycle facility type affects the perceived level of risk. Shared-use roads were ranked as riskiest, while separated bike lanes were least risky. Bicycle roads with no separated safety barriers had higher risks. Heavy traffic jams increased danger among cyclists. Women gave higher risk ratings than men. The perceived levels of risk were then compared with the previously developed risk index and they correlated well. (4) Conclusions: This confirms that the risk index can reliably evaluate the degree of risk of each road segment.

Keywords: bicycle simulator , perceived risk , risk factors , sustainability mobility modes , users' experience

Uban Air Mobility is a new concept of air transportation system that include platforms with different specifications, mainly vertical take-off and landing vehicles, aiming to transport goods and people within urban settings by alternatively managing traffic in congested ground mobility. To ensure the operability of Urban air Mobility, some challenges and objectives in terms of public acceptance and effective design of operational scenarios still need to be achieved before its full integration and deployment. Extended Reality technologies can contribute to the successful realization of these goals as they offer immersive human-machine interfaces that can improve the implementation of such innovative transportation systems. This paper explores Extended Reality-based scenarios and their potential applications for Urban Air Mobility within the framework of the Reality Virtuality Continuum and end user of Urban Air Mobility are elicited. The most promising applications of the proposed approach are discussed, focusing on the main feature that can be enhanced though the adoption of Extended Reality-based technologies.

Keywords: Sustainable Mobility , U-space services , UAM , UTM , XR

In the field of aircraft system engineering, this research work aims to bridge the gap between conceptual design and quantitative analysis, with a specific focus on the installation of aircraft passenger seats. To achieve this objective, a comprehensive analysis of seat installation process for commercial aircraft was carried out to identify and describe criticalities associated with this manufacturing phase. Different means were used to gather information, starting from the analysis of technical documents, and conducting interviews with industry experts. The research methodology employs a unique translation mechanism, harnessing the power of scoring matrices which are based on a graduated scale ranging from 1 (best option) to 5 (worst option). The scoring matrix serves as a tool for quantifying and translating the qualitative data gathered from the experts into quantitative analysis reflecting the installation process workload. By quantifying the qualitative information provided by the experts, this approach enables a systematic evaluation of seat installation and aids in decision-making within the aircraft assembly domain. In essence, this research contributes a structured and rigorous framework for assessing the ease of installing aircraft components, with a specific emphasis on seats, resulting in an improved assembly process of aircraft.

Keywords: aircraft assembly , Design methodology , seat installation , system engineering , technologies , tools

The work described in this paper aims to present a systematic approach for efficiently exploiting Computational Fluid Dynamics (CFD) simulations in early conceptual design phases. More specifically, the proposed procedure strives to use simplified CFD models with a limited amount of computational resources. It is then expected to better support preliminary evaluations of the fluid dynamic efficiency of early ideas, as well as to support idea generation. The proposed approach is focused on the conceptual design phase, intended here as the design stage where new ideas about forms and geometries for the fluid volume are generated. A systematic and iterative procedure has been devised and constitutes the core of the approach, which has been applied to a real case study, involving both industrial and academic staff. Five different concepts have been proposed and then evaluated from a manufacturing point of view by the industrial staff, who identified a preferred solution, which has been further developed and then verified through an additional simulation. The results show that by using the proposed systematic procedure, it has been possible to prevent the firm from developing a non-optimal solution, previously hypothesized by following a simple intuitive path based on precedent experiences. This work shows that the adoption of systematic design approaches integrated with modern tools like CFD can actually be a valid support also for SMEs.

Keywords: Air intake , CFD , Creativity , Design methods , Engineering design , Systematic design

An important aspect of Advanced Driver-Assistance Systems is the real-time monitoring of the driver and the interaction with him/her. In this scenario, the proposed work is focused on the development of an innovative system capable of analyzing the driver's state and interact with him/her in a innovative way. In particular, the driver monitoring is obtained through the implementation of a multimodal approach that exploits deep learning and data fusion techniques while the interaction is achieved through sound signals elaborated with digital signal processing algorithm for the creation of an immersive scenario.

Keywords: driver monitoring , vehicle interaction