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In the present paper, the acoustic emission (AE) device is used with an innovative approach, based on the calculation of P-wave propagation velocity (vp ), to detect the stiffness characteristics and the diffused damage of in-service old concrete structures. The paper presents the result of a recent testing campaign carried out on the slant pillars composing the vertical bearing structures designed by Pier Luigi Nervi in one of his most iconic buildings: the Hall B of Torino Esposizioni. In order to investigate the properties of these inclined pillars, localizations of artificial sources (hammer impacts), by the triangulation procedure, were performed on three different inclined elements characterized by stiffness discrepancies due to different causes: the casting procedures, executed in different stages, and the enlargement of the hall happened a few years later the beginning of the construction. In the present work, the relationship between the velocity of AE signals and the elastic characteristics (principally elastic modulus, E) is evaluated in order to discriminate the stiffness level of the slanted pillars. The procedure presented made it possible to develop an innovative investigation method able to estimate, by means of AE, the state of conservation and the elastic properties and the damage level of the monitored concrete and reinforced concrete structures.

The most frequent prodromes of COVID-19 infection are fever and signs/symptoms of incipient respiratory diseases such as cough and shortness of breath or tachypnea. However, it is not infrequent that in patients infected with COVID-19, in addition to respiratory manifestations, cardiac rhythm alterations are also present which can be an early sign of an acute cardiovascular syndrome. It is therefore of utmost importance, especially for health care and civil protection workers who are most exposed to the infection, to detect the prodromal symptoms of this infection in order to be able to make a diagnosis of possible positivity to COVID-19 infection as quickly as possible and therefore to provide their immediate insertion in the isolation/therapy protocols. Here a prototype of a smart face mask is presented: the AG47-SmartMask. In addition to having the function of both an active and passive anti COVID-19 filter, the latter by an electro-heated filter brought to a minimum temperature of 38°C, the AG47-SmartMask also allows the continuous monitoring of numerous cardio-pulmonary variables. Several specific sensors are incorporated into the mask in an original way that assess the inside mask temperature, relative humidity and air pressure together with the auricular assessment of body temperature, heart rate and percentage of oxygen saturation of haemoglobin. Sensors work in synergy with an advanced telemedicine platform. To validate the device, twenty workers engaged in a vegetable packaging chain tested the tool simulating, while working, both tachypnea and cough, and the AG47-SmartMask faithfully quantified the simulated dyspnoic events.

In this paper the mechanical characteristics of an innovative bioplastic material, the HBP® -HempBioPlastic® filament, is investigated. HBP® was recently patented by an Italian company Kanésis that focused its activity on nature-derived materials. The filaments are the upshot of an original process allowing to reuse the surplus of the agricultural supply chains and transform it into new sustainable materials. At first, the 3D printed HBP® samples were tested in tensile tests according to the ASTMD638 standard and monitored in term of deformations by the Digital Image Correlation techniques (DIC) in order to evaluate the stress-strain behavior of different HBP® textures under loading. In addition, using the HBP® and the results coming from the experimental campaign, the design of an exhibition pavilion was proposed. The pavilion was modelled starting from the geometric construction of the fullerene. The supporting modular structure is combined by HBP® modular elements, that can be produced by 3D printing or moulding. Finally, in order to demonstrate the feasibility of the proposed pavilion, a linear finite element analysis is presented on the base of the experimentally determined mechanical properties of HBP® elements, under the effects of wind and seismic environmental actions.

Arches are employed for bridges. This particular type of structures, characterized by a very old use tradition, is nowadays, widely exploited because of its strength, resilience, cost-effectiveness and charm. In recent years, a more conscious design approach that focuses on a more proper use of the building materials combined with the increasing of the computational capability of the modern computers, has led the research in the civil engineering field to the study of optimization algorithms applications aimed at the definition of the best design parameters. In this paper, a differential formulation and a MATLAB code for the calculation of the internal stresses in the arch structure are proposed. Then, the application of a machine learning algorithm, the genetic algorithm, for the calculation of the geometrical parameters, that allows to minimize the quantity of material that constitute the arch structures, is implemented. In this phase, the method used to calculate the stresses has been considered as a constraint function to reduce the range of the solutions to the only ones able to bear the design loads with the smallest volume. In particular, some case studies with different cross-sections are reported to prove the validity of the method and to compare the obtained results in terms of optimization effectiveness.

The new serious consideration to masonry and non-metallic structures evidenced their direct prospective to be, even in the present days, advanced architectural and engineering solutions. In the present paper, a form finding for a cement based tessellated pierced vault is studied. The multi-body rope approach (MRA) was used to define compression-only vault optimal shapes. Successively, the thrust network analysis (TNA) was implemented by Rhino-vault for a further validation of the shape and the definition of different tessellation meshes of the surfaces, according to different hole pattern configuration. Different piercing percentage of the vaults were considered and compared for the best solution identification. In addition, the geometrical solutions were analyzed by means of global stability analysis, taking into account the different positions of the holes. Furthermore, 3D printing with a Fuse Deposition Modeling (FDM) technique in polylactide (PLA) material (completely eco-friendly) is used for the construction of the formworks of the cement based blocks (dowels) useful for the assembly of a vault scaled prototype. The prototype of the vault, characterized by a certain piercing percentage was subjected to different loading conditions and monitored by a non-contact device based on the Digital Image Correlation (DIC) technique. The 3D-DIC was performed to recognize the structural behavior during the loading process of the model (prototype). DIC measurements were used to recognize in advance the critical condition of the vault under loading and the displacement measurements were correlated to the different loading phases up to the collapse condition.

An impressive fire devastated the cathedral of Notre Dame in Paris, one of the symbols of European architecture. The flames spread from the scaffolding embracing the base of the spire on the cathedral roof. The fire blazed up in the church during the religious celebration on April 15th at 6:45 p.m. The fire enveloped abruptly the roof and the spire erected by Viollet-le-Duc in 1860. The collapse took place about 80 min around 8 p.m [ [1] , [2] , [3] ]. Today, the clamor is all around, the silence is in the heart. At the time of the present paper, the causes of the catastrophe are still wrapped in a dense smoke, like the one generated by the burning “forest”– as the roof structure was called. This is the figure of the disaster. The Cathedral’s inferno devastated a world treasure, prompting an outpouring of collective sorrow and soul-searching over whether to recreate the destroyed oak-framed roofing and spire or adapt the cathedral to the 21st century. In the present paper, a computer-based fire simulation model based on Computational Fluid Dynamics (CFD) was used to determine the spread of fire and smokes into the structure of the roof and, at the same time, an original evaluation of the residual strength taking into account the fire effect and the water saturation in the limestone after the extinguishing was estimated. The residual strength ratio (RSR) and the compressive strength (CS) evolution are carefully evaluated for the injured structures. An estimation of the residual effective strength of the masonry walls of the Cathedral is proposed.

In this work the uncertainties related to the optimal planning/allocation of government subsidies for residential building stocks retrofits are considered and the uncertainty based planning problem is formulated and solved as a multi-objective, constrained problem. Different multi-objective algorithms are considered with the idea to determine the most effective and efficient approach that can be customized as planning tool to be used by the public administration personnel. The preliminary comparison between 2 multi-objective evolutionary algorithms and a deterministic one is presented and optimal/pareto results are analysed.

Planetary gear drives are widely employed in electrical and hydraulic actuation systems, to adapt a high speed, low torque motor to a low speed, high torque user, within strict weight and volume constraints. During the early design phases of these devices, accurate yet simple simulation models are required to evaluate the performance of a given configuration of the device. Similar models are also useful within diagnostic and health monitoring analyses of existing machines, as a discrepancy between the actual behaviour of the physical system and that predicted by its digital twin may be the effect of a damage. This work compares different models available in literature for the efficiency of high gear ratio mechanical transmissions; the models are applied to multiple arrangements common for planetary drives, and the results in form of an efficiency map for the transmissions are compared and discussed. The simulations provide different levels of detail, and require different levels of knowledge about the specific architecture of the system. All of them are able to deal with dry friction; additionally, the different behaviour of the transmission under the effect loads aligned in the same direction of speed or in the opposite one is accounted for.

Over the last years, different methods, physical and mathematical, were used to find the optimal shape, minimizing the internal stresses, of shallow grid shells. As far as their original organic shape is concerned, the design of grid shell structures inspired architects and structural engineers in more than one way. Throughout history, the resolution of the problem related to the structural form-finding buried its roots on the activity of researchers and innovators. In the present paper an original approach for the form-finding is obtained by dynamic numerical simulation of hanging net, subjected to gravity load, over the time domain. In particular, the proposed method for the definition of the form is based on a multi-body rope approach (MRA) with masses connected by inextensible ropes characterized by a certain slack coefficient (sc) and by the degree of the constraint conditions. These parameters played a fundamental role in the definition of the shallowness ratio of the grid, and therefore in the effect of the instability of the reversed shape (grid shell) under loading. Moreover, in the case of shells with a very large number of nodes, a combined procedure based on non-uniform rational basis-splines (NURBS) formulation is proposed for the form-finding. Finally, step-by-step nonlinear analyses for the grid shells obtained by MRA were performed by a displacement control scheme, applying vertical incremental displacement to the nodes. Three circular grid shells were generated and analysed considering the effects of geometrical imperfections on the coupled instabilities varying the shallowness ratio.

The paper presents a test method for evaluating air leakage in rodless cylinders with longitudinal slot and sealing band. To this aim a specific test rig was developed in order to carry out leakage tests under different operating conditions. Specifically, the performance of the sealing system consisting of the band, seal, and barrel is analyzed, identifying the critical conditions and factors that influence operation. Particular importance was assigned to selecting band and seal cross-sections in order to minimize leakage and thus limit energy consumption. A final rodless configuration with considerably reduced leakage was proposed.

In this work the energy cost of a human operator during the harvesting of saffron flowers is discussed. The amounts of energy cost was achieved for a traditional harvesting hand-made activity compared to a harvesting phase with a facilitator machine. In the paper the facilitator machine prototype is described with its mechanical performances. Oxygen uptake (VO2) and carbon dioxide consumption (VCO2) were taken in five male healthy volunteers using a progressive exercise test on a cycle ergometer to calculate the respiratory ratio (VCO2/VO2) corresponding to the anaerobic threshold (AT) which, just it exceed 1, indicates the fatigue onset. VO2 was also assessed when volunteers simulated hand-made saffron harvesting or assisted by the facilitator device, to establish if the VO2 reached or not the AT value/fatigue onset in the one or in the other harvesting modalities.

The present work focuses on the chemical response of Ag oxalate powders to the collision of rods in controlled rod drop experiments performed by using suitably designed reactors. Powder layers of different thickness were submitted to the collision of cylindrical rods with selected radius, mass, and collision velocity. The experimental findings indicate that collisions are able to induce the partial decomposition of Ag oxalate into metallic Ag and gaseous carbon dioxide. The mass of Ag oxalate decomposed is proportional to the collision energy. Being the impact energy the same, the mass decomposed is inversely proportional to the surface area of the powder layer. In addition, it increases irregularly as the thickness of the powder layer increases. The results obtained suggest that rod drop experiments can be profitably used to promote and investigate mechanochemical transformations.

This paper deals with the analysis of the contact pressure distribution at the rod/guide bearing interface of a linear pneumatic actuator. The investigation was carried out both experimentally, using pressure-sensitive film, and numerically by means of finite element analysis. By using the numerical model, it was possible to identify design changes to the cylinder front head whereby contact pressure at the bearing/rod interface can be redistributed. Operating conditions that are more advantageous in terms of wear and durability can thus be achieved.

In this article a calf-plantar sequential pneumatic compression innovative device, consisting of three sensorized and PLC-controlled chambers, is designed and implemented. It performs a massage on the calf surface and on the foot sole at a given controlled pressure level and frequency and, in addition, carries out the ankle passive movement. Preliminary tests were performed on patients, using a commercial apparatus normally devoted to lymphatic drainage massage. In testing the mechatronic apparatus under real working conditions three air pressure transducers are used to feedback control the actuation system and the pressure trends in the actuator chambers during massage are here reported.

This article describes the design of a new test rig for measuring the friction force in pneumatic components and seals. The test rig was designed in order to measure both the overall friction force in a pneumatic cylinder or a valve as a whole, and the single contribution to friction force caused by the sliding seals. To this end, special fixtures and devices were designed and manufactured in order to measure the friction force in piston seals, rod seals and cartridge valve seals individually. Results of friction measurements carried out on pneumatic cylinders with similar characteristics but produced by different manufacturers are presented and compared. A test procedure and a methodology, in order to separate the contributions of the individual seals from the overall friction of the cylinders, is presented.

An experimental procedure is presented for measuring contact pressure between a pneumatic seal and its counterface. Measurements were performed using pressure-sensitive films, for which a suited calibration procedure was developed, also taking into account humidity influence. Having validated the experimental procedure on a lip seal rectilinear specimen, tests were carried out on commercial piston seals. Results were compared with those coming from numerical simulations performed using a finite-elements analysis.

In this paper, we describe the design and construction of a cam mechanism to convert a revolute motion into a symmetrical oscillating harmonic movement. The mechanism consists of a harmonic cam driven by a revolute electric motor joined to a follower by a desmodromic constraint. The linear reciprocating motion of the follower was then transmitted, by a rack-pinion mechanism, to a final device that oscillates symmetrically. The entire mechanism was designed to be used as the propeller of a boat model. The final device, indeed, will be connected to a tail that propels the boat. On account of the peculiar application for which the device is intended, the need for symmetrical motion of the tail—either in a cycle, from side to side and return, or in a semi-cycle, from side to side—becomes evident. The analysis of the kinematics and the analytic model of its dynamics are presented throughout the paper. A numerical model, able to capture the mechanism performance when the friction effects were taken int...

The re-design at the front-head/guide-bearing interface of a linear pneumatic actuator is proposed in this paper. Design changes were performed by means of finite element analyses. Contact pressure and its redistribution at the rod-guide interface were assumed to be the “leading parameter” in this process to promote improvements of tribological behaviour, viz., reduction of guide-bearing wear and increase of cylinder life. Wear measurements and life tests made possible a comparison of pneumatic actuator life: these were modified on the basis of the various re-design solutions proposed. Therefore, a validation of the model׳s predicted conditions was possible.