A big problem in cruise ships is related to noise and vibrations generated by engines and exhaust stacks. Reduction or control of ship noise has traditionally been implemented by passive means, such as by the use of vibration isolation mounts, flexible pipe-work, and interior acoustic absorbing materials. However, these passive noise control techniques are effective mostly for attenuating high-frequency noise, while they are generally ineffective for controlling the low-frequency one. This paper presents an active vibration control of ship bulkheads based on independent modal control technique using magnetostrictive actuators. In the first part of the research, a mock up of the vibrating bulkhead is reproduced in laboratory and a mechanical model of both the system and actuators has been realized. The modal control has then been simulated focusing on actuators and sensors position and number to improve the system’s controllability and observability properties and hence allow to obtain optimal performances in terms of vibration reduction. The influence of boundary conditions has also been taken into account in order to be able to predict the control logic performances in the various possible scenarios.

In 2018 a collaborative project between Politecnico di Milano (PoliMI) and Regione Lombardia (RL) was launched to join forces and expertise toward the improvement of the regional transport infrastructures maintenance management. One of the project goals was the development of regional guidelines aimed to support the design and implementation of monitoring systems for bridges. The focus of this paper is on the illustration of the Monitoring Regional (MoRe) guidelines and of their implementation on nine pilot monitoring systems designed and deployed within the project. The (MoRe) guidelines tackle the entire monitoring process from the analyses of the monitoring goals and the preliminary investigations needed to the identification of the phenomena and relevant indicators to monitor, up to the selection of monitoring devices and the presentation of results. A short illustration of the permanent monitoring systems installed on nine exemplary bridges in the Lombardia region concludes the paper.

Introduction Soft robotic wearable devices, referred to as exosuits, can be a valid alternative to rigid exoskeletons when it comes to daily upper limb support. Indeed, their inherent flexibility improves comfort, usability, and portability while not constraining the user’s natural degrees of freedom. This review is meant to guide the reader in understanding the current approaches across all design and production steps that might be exploited when developing an upper limb robotic exosuit. Methods The literature research regarding such devices was conducted in PubMed, Scopus, and Web of Science. The investigated features are the intended scenario, type of actuation, supported degrees of freedom, low-level control, high-level control with a focus on intention detection, technology readiness level, and type of experiments conducted to evaluate the device. Results A total of 105 articles were collected, describing 69 different devices. Devices were grouped according to their actuation type. More than 80% of devices are meant either for rehabilitation, assistance, or both. The most exploited actuation types are pneumatic (52%) and DC motors with cable transmission (29%). Most devices actuate 1 (56%) or 2 (28%) degrees of freedom, and the most targeted joints are the elbow and the shoulder. Intention detection strategies are implemented in 33% of the suits and include the use of switches and buttons, IMUs, stretch and bending sensors, EMG and EEG measurements. Most devices (75%) score a technology readiness level of 4 or 5. Conclusion Although few devices can be considered ready to reach the market, exosuits show very high potential for the assistance of daily activities. Clinical trials exploiting shared evaluation metrics are needed to assess the effectiveness of upper limb exosuits on target users.

Among all aquatic species, mantas and rays swim by flapping their pectoral fins; this motion is similar to other fishes in terms of efficiency, but it gives better maneuverability and agility in turning. The fin's motion is featured by a traveling wave going opposite to the forward motion, producing a force thanks to momentum conservation. This article aims at understanding the swimming dynamics of rays, focusing on energy efficiency. A computational fluid dynamics (CFD) model of the swimming motion of a cownose ray has been implemented in openfoam, simulating the acceleration of the fish from still to the steady-state velocity using an overset mesh. In this analysis, the one degree-of-freedom dynamics of forward swimming is solved together with the fluid velocity and pressure. The effect of frequency and wavelength of fin motion on thrust, power, and velocity has been investigated and an analysis of the vortices in the wake showed has been performed. The energy efficiency of a self-propelled body has been defined in a novel way and it has been calculated for different motion conditions. The results showed that batoid fishes swim with high energy efficiency and that they are a promising source of inspiration for biomimetic autonomous underwater vehicles.

Interest in autonomous underwater vehicles is constantly increasing following the emerging needs of underwater exploration and military purposes. Thus, several new propulsion mechanisms are studied and developed. Fish swimming is a promising source of inspiration because they outperform conventional propellers in terms of energy efficiency and maneuvrability. Their advantages are not only due to the streamlined shape and their low-drag skin but also, above all, due to the particular fin motion, which makes thrust generation possible with small energy dissipation. This paper analyses the motion of batoid fishes that are considered highly efficient by biologists. Their motion is reproduced by different linkage mechanisms optimized to fit underwater robots. A bioinspired robot mimicking cownose ray locomotion is, then, designed and built. Numerical analysis of its dynamics allows us to measure the size of actuators and to estimate the robot behavior. Finally, the control algorithm that maintains the mechanism synchronization according to different strategies is described and some experimental results are presented.

In 2018 a collaborative project between Politecnico di Milano (PoliMI) and Regione Lombardia (RL) was launched to join forces and expertise toward the improvement of the regional transport infrastructures maintenance management. The general goal of the project is the development of a risk-based maintenance prioritization methodology supported by information retrieved by inspection and monitoring operations. The focus of this paper is on the illustration of the monitoring regional (MoRe) guidelines, developed within the project, to provide general guidance on the design and implementation of monitoring systems for road and riverine bridges. They tackle the entire monitoring process from the analyses of the monitoring goals and the preliminary investigations to the identification of the phenomena and relevant indicators to monitor, up to the selection of monitoring devices and the presentation of results. A short illustration of the pilot monitoring systems installed on nine bridges on the Lombardia roadway network concludes the paper.

Complexity is the central theme of our contemporary age, and what technical culture needs today is to know how to manage it. Knowing how to deal with situations that are anything but straightforward – situations that require flexible thinking, the ability to establish a dialogue between fields of knowledge, and the intermingling of points of view that are, by their very nature, heterogeneous. If this is the direction that needs to be taken in order to tackle the major challenges of the future – from energy to the environment, healthcare to data management, and so on – then it naturally follows that the old monodisciplinary paradigm that we have grown accustomed to as a result of tradition, divided up and compartmentalised, is now outdated. In order to face the great trials of our time, of which architecture is an interpreter, we need a broader vision. Indeed, the growing speed of technological evolution, its pervasiveness and the impact that this is capable of having on the community and our future increasingly point towards the validity of a multifaceted approach that reflects and anticipates the dynamics of social development. If complexity is in fact the theme of the future, then, we cannot avoid engaging in a careful reflection on the dualism between specialisation and a systemic vision; on the relationship between a solid specialist culture, required to understand problems in depth, and a broader cultural perspective, crucial to understanding the direction that the world is moving in. Here is a very simple example: we cannot begin to think about creating new spaces and new functions for living and dwelling if we do not first consider some of the major issues dominating our era. One of the many, and one that I hold particularly dear, is mobility: a new concept of mobility – sustainable, intelligent, shared – redefines everything that revolves around it, starting with our behaviours. And in order to analyse these behaviours, we must first understand the potential and impact of the new technologies underpinning them. It goes without saying that the architect, the engineer, the sociologist and the visionary start-up must all be able to interface within a common framework, a shared perspective, a circular approach. As such, the task that the university is faced with is arming its students, as well as the professionals of today and tomorrow, with skills that, whilst based on solid disciplinary foundations, are not isolated in monothematic contexts, but instead benefit from complementary paths and interaction. Points of comparison and dialogue between different fields of knowledge, different experiences, different practices. At the heart of what we refer to as “polytechnic culture” is the value of design, which everyone contributes to with methods and tools that are different, yet all equally useful: some apply the laws of dynamics, others the laws of physics or electronics; some use an experimental method, others are more firmly rooted in tradition. Designing becomes synonymous with sharing and hybridising, in that it means forming a complex response to a need expressed by the community. It is then worth reflecting upon how, in a civilisation in which everything is contemporary – in which a unitary and evolutionary conception of time has disappeared entirely – we are forced to design in a condition of great discontinuity. Whilst on the one hand, the relentless forward march of technology has got us used to fast dynamics, on the other, space is notoriously subject to slow transformations. Indeed, an architectural project takes months to design and years to actually construct. It also has an intrinsic characteristic, namely surviving the passage of time, of preserving memory and seeing the end of its lifecycle only decades down the line. Whereas once upon a time, historical developments were slow and predictable – as it was easy enough to imagine what would happen over the course of the next twenty years – nowadays, this sort of long-term vision is impossible because society evolves not only rapidly, but also in radical leaps and bounds. Hence the adjective “disruptive” which so often recurs in our conversations: the unexpected, changing our paradigms. Unexpected, just like COVID-19: a catalyst which accelerated some of the major technological changes that were underway, first and foremost digital technology, the true potential of which emerged clearly as we sought to tackle the health crisis. From distance learning to remote working, digital technology allowed us to carry on with our lives, but at the same time, it emptied out schools and universities, offices and skyscrapers; it reassigned new functions to our living spaces; it redefined interpersonal relationships; it depopulated entire urban areas and brought international mobility to a standstill. That said, despite the fact that technology managed to soften the blow of a sudden and dramatic situation almost overnight, I struggle to believe that the pandemic and social distancing will empty out the cities in any definitive way. On the contrary, I believe that after this not-so-brief interlude, the large urban centres will once again become lively, dynamic hubs of activity. They will continue to offer that unique and eclectic collection of ideas, values and opportunities that smaller settlements struggle to ever develop. Architecture will then be faced with the challenge of responding to this distancing and emptying by designing a different understanding of what “being there” means, and in order to do so, it will have to interface with a variety of contexts. Architecture will have the task of redefining a new living experience, of developing a complex conception of planning that lies on the borderline between the opportunities offered by remote learning and working and our needs in terms of socialising; between the needs of the economy and those of protecting the nation’s health; between an immediate response dictated by an emergency and a need for long-term sustainability. In the case of our universities, it will mean completely overhauling our idea of campus life. Whereas some of the most prestigious universities in the world, starting with Cambridge, are offering entirely online courses, riding the long wave of COVID and using the tools offered by digital technology, I believe that, on the contrary, it is absolutely essential to restore a sense of physicality and experience. I believe that the time is right to once again start talking about physical spaces in response to virtual classrooms. I consider it necessary to do everything we can to ensure that our universities continue to draw in talented young people who choose to engage in a first-hand experience of the academic spaces and cities playing host to them – the cities that reflect these people. It is therefore not enough to welcome new students with open arms: we must instead offer them a unique experience of life, from campus life to the services that the wider area can offer. The university needs a modern, welcoming city in order to be attractive, and vice versa: a double bond, a two-way street. An experience that will take tangible form within the university itself – with interactive classrooms, spaces dedicated to hospitality, sports, social interaction, study, workshops – as well as intangible form in the values that we will be able to convey in places that increasingly represent points of engagement and personal growth. Places which can wholeheartedly embody the approach to complexity mentioned earlier. The lesson to draw from this pandemic is that in order to respond to complex challenges, we must turn to knowledge as our starting point. And so, after dedicating years to minor jobs and maintenance work, the university is once again positioning itself as an active force engaging in society and change. This is the best guarantee for the future: ensuring that the classrooms and lecture halls of universities everywhere can once again become “construction sites for knowledge”. And these sites – as our alumnus and master Renzo Piano has taught us – are wellsprings of hope, even and above all in times of uncertainty such as we are currently living through.

Monitoring and diagnosis of civil structures has become a popular topic in the last years, especially through the use of non-invasive tests and techniques. Moreover, the spread of operational modal analysis, that exploit ambient excitations of structures to estimate their modal parameters, allowed to reduce the costs associated to the dynamic identification. In this paper, a technique for the diagnosis of common civil structures, such as residential buildings or warehouses, is presented in order to identify local stiffness decreases that can potentially be associated to structural failures. The technique has been tested on a real warehouse built in 1960 and the results have been analyzed demonstrating the effectiveness of the methodology.

One field in which nature outperforms current technology is fish swimming, because its efficiency, manoeuvrability and noise are far better than those of typical ship propellers. These advantages are not only due to the streamlined shape and the low-drag skin, but also and above all to the propulsion mechanism, which makes thrust generation possible with small energy dissipation in vortices. Nowadays the interest in autonomous underwater vehicles is in constant increase following the emerging needs of underwater mining and fish farming. Batoid fishes produce thrust with their pectoral fins, they essentially produce a wave travelling in the direction opposite to their motion, pushing water backwards and gaining thrust as a consequence of momentum conservation. The motion of the fin has been studied and reproduced with a series of articulated mechanisms. In this work the optimization of the mechanism’s geometry is described and the experimental results on the reconstructed fin are presented. Moreover, a bioinspired robot mimicking cownose ray locomotion has been designed and built. In this paper the functioning of this robot is shown.

In this paper we report on adiabatic pumping in quasiperiodic stiffness-modulated beams. We show that distinct topological states populating nontrivial gaps can nucleate avoided crossings characterized by edge-to-edge transitions. Such states are inherently coupled when a smooth variation of the modulation phase is induced along a synthetic dimension, resulting in topological edge-to-edge transport stemming from distinct polarizations of the crossing states. We first present a general framework to estimate the required modulation speed for a given transition probability in time. Then this analysis tool is exploited to tailor topological pumping in a stiffness-modulated beam.

Among all aquatic species, mantas and rays swim by oscillating their pectoral fins; this motion is similar to other fishes in term of efficiency, but it gives better agility in turning with respect to fishes moving their caudal fin. The fin motion is featured by a travelling wave going opposite to the forward motion, producing a force thanks to momentum conservation. Another contribution to the generation of thrust is given by the generation of a vortex in correspondence of the leading edge of the fin, which pulls the fish forward thanks to the lower pressure in its centre. In literature these contributions have been highlighted, but it remains to understand which one of these two mechanisms is prevailing according to different conditions of swimming, how they affect each other and what is the influence of the two on energetical efficiency. The object of this activity is to investigate how thrust generation is influenced by geometrical characteristics of the fin, such as size, geometry and flexibility and by parameters of motion, such as speed, amplitude and frequency of fin oscillation and velocity of the travelling wave. A CFD model of the fish has been implemented in OpenFOAM, not only confirming that both upstroke and downstroke contribute positively to the forward movement according to the momentum conservation principle, but also highlighting the formation of a leading-edge vortex enhancing thrust generation. The description of how thrust generation is linked to motion parameters is simulated also coupling the CFD with a multibody to simulate the whole motion in its complexity.

A Fast Tracker analog front end for small-diameter Muon Drift Tube (sMDT) detectors is hereby presented. The analog channel has been integrated in 28 nm CMOS technology and significantly improves state-of-the-art sMDT read-out systems thanks to a novel signal processing technique exploited to extract information from sMDT detectors speeding-up the processing time and to limit fake events detection. The main idea is to implement a fast reset of all continuous-time analog stages that occurs just after the charge (i.e. event) detection. This has two main advantages for sMDT read-out: fast processing and negligible signal corruption due to non-relevant pile-up signals. Nonetheless, the realization in 28nm bulk-CMOS technology implies challenges for analog design but advantages in terms of speed, area occupancy and radiation hardness. The proposed analog channel occupies 0.03 mm 2 and consumes 1.9 mW from 1 V supply voltage.

The Phase-II Upgrade of the ATLAS Muon Detector requires new electronics for the readout of the MDT drift tubes. The first processing stage, the Amplifier-Shaper-Discriminator (ASD), determines the performance of the readout for crucial parameters like time resolution, gain uniformity, efficiency and noise rejection. An 8-channel ASD chip, using the IBM 130 nm CMOS 8RF-DM technology, has been designed, produced and tested. The area of the chip is 2.2 x 2.9 square mm size. We present results of detailed measurements as well as a comparision with simulation results of the chip behaviour at three different levels of detail.

Several examples of control strategies for the seismic protection of civil structures, ranging from passive to active and semi-active have been presented in the scientific literature, and often applied in the market. However, none of them proved to be absent of high employment costs or burdensome installations. For this reason, the low-cost Active Mass Damper (AMD) shown in this work and capable of automated self-tuning, control and continuous monitoring of the structures represents an attractive solution. The device has been designed and tested on the numerical model of a scaled steel made three story building. In particular its working principle and the ISAAC algorithm for automatic identification are presented and its robustness against modelling and estimation errors is analyzed. The methodology allows to avoid the study of specific solutions for each case, thus making possible the adoption of such systems also for already existing and common structures.

In this work a completely automated output-only Modal Analysis procedure is presented and all its benefits are listed. Based on the merging of different Operational Modal Analysis methods and a statistical approach, the identification process has been improved becoming more robust and giving as results only the real natural frequencies, damping ratios and mode shapes of the system. The effect of the temperature can be taken into account as well, leading to the creation of a better tool for automated Structural Health Monitoring. The algorithm has been developed and tested on a numerical model of a scaled three-story steel building present in the laboratories of Politecnico di Milano.

Application of active vibration control often require a complex setup. When large structures are considered, it is often necessary to have a high number of sensors and actuators, suitably cabled, in addition to all the devices necessary to condition and amplify the signals of measurement and control and to execute in real time the control algorithms synthesized. This work arises from the need to simplify this situation, developing a stand-alone device that is able of carrying out operations of vibration control in an autonomous way, thus containing in itself an actuator, the sensors needed to evaluate the vibratory state of the structure, and a controller. The design of the smart damper covers many aspects and requires a strong integration of different disciplines. A prototype has been realized and tested on a vibrating structure. The experimental results show good performance in suppress vibration.

Active vibration suppression can be profitably implemented on large structures to enhance their performance (eg. comfort, fatigue life, etc.). Application on large structures, however, often require a complex setup that makes these solutions too complex to be effectively used. That is because of the high number of sensors and actuators, suitably cabled, in addition to all the devices necessary to condition and amplify the signals of measurement and control and to execute in real time the control algorithms synthesized. One of the most effective technique to reach this goal is to increase the equivalent damping of the system and then the dissipation of the kinetic energy (the so called skyhook damping technique). This work is aimed to simplify this setup by using stand-alone smart dampers developed to carry out operations of vibration control in an autonomous way, thus containing an actuator, the sensors needed to evaluate the vibratory state of the structure, and a micro-controller embedding different control algorithm. The paper shows that the use of more devices, each working independently to perform a decentralized control, can be profitably used to better suppress vibration of the structure.

The Total Ionizing Dose (TID) levels foreseen after the future upgrade of the CERN Large Hadron Collider (High Luminosity LHC) will heavily influence the performance of the electronics. A TID level of 1GigaRad will be accumulated in the innermost layer of the pixel detector in 10 years of operations, which could damage the readout circuits behavior with important failures in the experiments. To prevent this situation, the choice of a proper technology for the readout ASICs represents a key point. This paper deals with the characterization of single transistors and of an analog circuit, both realized in a TSMC 28nm bulk CMOS technology, after being irradiated with 1 GigaRad TID. nMOS devices result more resistant than pMOS showing a weak degradation of the electrical parameters. Nevertheless, the considerable leakage current increment is not negligible because it could affect analog circuits as that hereby presented. In the proposed analog circuit, the high radiation level induces a 20% gain reduction and an 80% slowdown of the Charge Sensitive Preamplifier time response.

IC-PIX28 (Integrated Circuit for PIXel detectors) is an analog read-out front-end fabricated in 28 nm Bulk-CMOS technology to process the charge signal produced by the pixel detector having 100 fF parasitic capacitance. The device is composed by a Charge Sensitive Pre-amplifier (CSPreamp) and a comparator. The development of IC-PIX28 manages several issues due to the poor analog performance of the standard-process MOS transistors in 28 nm Bulk-CMOS technology, whose choice is motivated by the expected rad-hard performance up to 1 Grad of Total Ionizing Dose. IC-PIX28 achieves performance robustness and low-power consumption by specific circuital solutions and it operates from a single 900 mV supply voltage. The full IC-PIX28 read-out channel consumes 4.3 mu W. The CSPreamp performs 35 mV/fC sensitivity, 40 dB Signal-to-Noise Ratio, and 0.033 fC (204 e(rms)(-)) Equivalent Noise Charge. Moreover, a switched-capacitors inverter-based comparator performs the Time-over-Threshold (ToT, at very low power consumption) with a measured ToT range of 500 ns convertible in a digital word with a high bit resolution (> 14).