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The direct molecular simulation method is used to obtain viscosity data from ab initio potential energy surfaces for air over a wide range of temperatures. These data are important for constitutive laws used to simulate hypersonic flows.

Multivessel coronary disease is frequent in older patients who underwent coronary angiography for acute coronary syndrome. Whether a complete revascularization or a culprit-only approach is preferable in these patients is still debated. We included consecutive patients aged ≥85 years, presenting with acute coronary syndrome and showing multivessel coronary disease at coronary angiography. Patients were grouped according to complete (residual SYNTAX score [RSS] 0 to 8) or incomplete (RSSgt;8) revascularization. Primary end point was the rate of major adverse cardiovascular events (MACEs, the composite of cardiovascular death, re-myocardial infarction [re-MI], clinically driven percutaneous coronary intervention, and rehospitalization because of cardiac disease) at 2 years follow-up. A total of 166 patients met the criteria for enrollment; 108 patients had a final RSS 0 to 8 (complete revascularization) and 58 patients had a final RSSgt;8 (incomplete revascularization). The rate of MACE was reduced in patients who underwent complete revascularization (35.2% vs 51.7%, p = 0.039, adjusted hazard ratio 0.60, 95% confidence interval 0.37 to 0.98, p = 0.04), a difference mainly driven by a reduction in re-MI (8.3% vs 19.0%, p = 0.045), clinically driven percutaneous coronary intervention (2.8% vs 19.0%, plt;0.001), and rehospitalization for cardiac disease (9.3% vs 24.1%, p = 0.009). Other independent predictors of MACE were active malignancy, previous MI, left ventricle ejection fractionlt;35% (increasing risk of events), and radial access (reducing risk of events). In conclusion, in patients aged ≥85 years, a complete revascularization is associated with a better prognosis, especially in terms of nonfatal events.

The number of applications of centrifugal pendulum vibration absorber (CPVA) in the automotive industry is growing steadily. The request of low fuel consumption and torque increase at low speed stimulated a large variety of drive concepts, such as downsizing, cylinder deactivation and hybrid powertrains. These design solutions increased the severity of torsional vibrations as well as the need of more effective devices to damp them out. For this reason, in recent years new types of CPVAs have appeared on the market. In particular, a pendulum with trapezoidal architecture, called torsichrone, has been developed. Its distinctive feature consists in the exploit of absorbers rotational kinetic energy for additional vibration attenuation. This paper investigates the kinematics and the nonlinear dynamics of trapezoidal dampers by means of intrinsic geometry theoretical tools and perturbation methods, respectively. It also offers insights about the influence of absorber center of mass path on the overall performance. Furthermore, optimization criteria for the rotational component of absorbers motion are proposed. On the basis of such analyses, design guidelines are recommended. Finally, to assess vibration isolation effectiveness and local stability behavior of trapezoidal CPVAs, a numerical comparison with the tautochrone parallel pendulum and results of multibody dynamics simulation are discussed.

The paper deals with the description of a methodology for addressing the real-time simulation of a soft membrane that can be deformed and torn by the interactive two-way action of the user. The methodology makes use of the combination of an efficient real-time solver, a haptic interface with force feedback and it is implemented in a virtual reality environment in order to achieve a very high level of immersion. The elastic properties of the membrane and the corresponding haptic feedback are modelled using an accurate structural model based on a flexible-rigid (f-rigid) multibody model. The f-rigid approach is a trade-off between the accuracy of a full finite element model and the computational efficiency of a multibody model able to be solved using high efficiency sequential impulse solver. The f-rigid model is verified by dedicated experimental tests about nonlinear deformation and rupture. The proposed methodology can be the base of the development of interactive training environments, ergonomic and usability studies and for the assessment and optimization of product design.

Recent developments in Materials and Radiofrequency Identification (RFID) technologies are currently boosting the development of new class of flexible and elastic epidermal devices for the wireless remote monitoring of biophysical parameters. As tightly bio-integrated with the skin, epidermal antennas are subjected to mechanical deformation during the natural movements and gestures of the human body. The experienced effect is a degradation of the communication performance of the RFID link. In this contribution, we evaluate the stiffness and the change of the radiation gain of on-skin UHF antennas in common gestures by a combined mechanical-electromagnetic model to provide a database and a modelling methodology to improve the design of deformation-tolerant skin antennas. The deformation of the skin is firstly quantified by using a contactless 3D scanner and then the communication impact is predicted by means of an electromagnetic analysis of stretched antennas for some relevant cases of thin-wire layouts. Preliminary numerical simulations and experimentations demonstrated that constraints over low stiffness and insensitivity of radiation gain could be not always compatible. An epidermal antenna may undergo up to 3–4 dB of gain degradation that converts to 30% reduction of the read distance for the strain orientation producing the minimum mechanical stiffness. The derived deformation database could be useful to improve the design of more robust epidermal antennas.

Centrifugal dampers are used to reduce the vibrations and irregularities of motion of rotating parts subjected to torque perturbations. Compliant mechanisms can be used for building compact and simple embodiments of such devices. On the other hand, the elasto-kinematic behaviour of compliant structures requires a more accurate design with respect to standard solutions. The study discusses a methodology for designing compliant centrifugal dampers based on the arrangement of a collection of leaf flexure hinges connecting peripheral masses. The design is based on the equations of motion written under the approximation of an equivalent pseudo-rigid assembly. To preserve accuracy, the pseudo-rigid surrogate model is deduced taking into account second-order kinematic invariants and Euler–Savary equations, thus providing second-order approximation of the relative motion. This strategy combines accuracy and simplicity. The design can benefit from design equations for choosing the dimensions of the flexible links and the weight of the peripheral masses. An example of application is also discussed and a comparison with a flexible multibody model is also presented to demonstrate the accuracy of the proposed methodology.

In Industry 4.0 era, rapid changes to the global landscape of manufacturing are transforming industrial plants in increasingly more complex digital systems. One of the most impactful innovations generated in this context is the “Digital Twin”, a digital copy of a physical asset, which is used to perform simulations, health predictions and life cycle management through the use of a synchronized data flow in the manufacturing plant. In this paper, an innovative approach is proposed in order to contribute to the current collection of applications of Digital Twin in manufacturing: a Digital Shadow cloud-based application to enhance quality control in the manufacturing process. In particular, the proposal comprises a Digital Shadow updated on high performance computing cloud infrastructure in order to recompute the performance prediction adopting a variation of the computer-aided engineering model shaped like the actual manufactured part. Thus, this methodology could make possible the qualification of even not compliant parts, and so shift the focus from the compliance to tolerance requirements to the compliance to usage requirements. The process is demonstrated adopting two examples: the structural assessment of the geometry of a shaft and the one of a simplified turbine blade. Moreover, the paper presents a discussion about the implications of the use of such a technology in the manufacturing context in terms of real-time implementation in a manufacturing line and lifecycle management.

Plant protection strategies in organic viticulture are based on the application of copper products, which is well known to generate a consistent environmental impact due to the accumulation of copper in soils and its negative effects on edaphic biodiversity. Life Green Grapes is a demonstrative project aiming to improve the sustainability of viticulture throughout the supply chain: from vine nursery to the table. In this paper, we report the main results obtained over three growing seasons (2018-2020) in response to the adoption of a strategy based on a reduced use of copper products in an organic vineyard. Plant protection treatments have been strictly planned according to forecasting models for disease development and fungicides have been partially substituted with products improving plant resistance. Green manure, known for contributing to the health of the vineyard, was also adopted. Results suggest the effectiveness of the “Green Grapes” strategy under low downy mildew pressure. Furthermore, no declines in grape quality have been observed; on the contrary, the synergic effect of green manure and substances beneficial to plants improved yield. An overall positive influence on the edaphic biodiversity was also observed.

The pin-in-the-slot joint is a common element in machines, and the dynamics of joints with clearances is an actively investigated topic. Important applications of such a joint can be found in Geneva mechanisms, robotized gear selectors, centrifugal vibration absorbers (CPVA) and other important mechanical devices. The paper will review the main analytical steps required to obtain the equations characterizing the different force contact models. Furthermore, a numerical test bench where such models are introduced for modeling the clearances between the pin and slot is proposed. In this regard, the present study will offer a comparison and discussion of the numerical results obtained with the different force contact models herein reviewed.

The protection of grapevine biodiversity and the safeguarding of genetic variability are certainly primary and topical objectives for wine research, especially in territories historically devoted to viticulture. To assess the autochthonous germplasm of three different districts of Southern Umbria (Central Italy), the plant material of 70 grapevines retrieved from reforested land plots or old vineyards was collected, and their genetic identity was investigated using 13 microsatellite markers (SSR). The results revealed the presence of 39 unique genotypes, divided into 24 already-known cultivars and 15 never-reported SSR profiles. Most of the grapevine accessions were then vegetatively propagated and cultivated in a vineyard collection both to be protected from extinction and to be evaluated at the ampelographic level. Overall, this work emphasizes the need for recovering the threatened genetic variability that characterizes minor neglected grapevine cultivars or biotypes of Southern Umbria germplasm, and the requirement to revalue and exploit the more valuable genetic resources to enhance the local agri-food economy.

The centrifugal pendulum is a device used to reduce torsional vibrations generated by motion irregularities of rotating machinery. It is adopted in many engineering applications. Even though different arrangements have been developed, because of its versatility, bifilar pendulum is the most commonly used architecture. In this paper, a new modeling approach and a novel design chart procedures for the trapezoidal bifilar centrifugal pendulum vibration absorber are proposed. In the first part, the case of parallel bifilar centrifugal pendulum is considered. In the second part, an innovative approach for the trapezoidal bifilar centrifugal pendulum design is proposed. For the first time, it has been established a dynamic equivalence between the trapezoidal bifilar and the unifilar centrifugal pendulum. This allowed the development of designs charts for trapezoidal bifilar pendulum. The dynamic equivalence is not only based on inertia, but involves concepts from the theory of curvature kinematics. The numerical results, obtained by means of multibody dynamics simulations, confirm the reliability of the procedure in terms of rotor torsional vibrations suppression. The methodology herein presented could be extended to cycloidal and epicycloidal vibration absorbers.

This paper proposes a refined methodology to simulate the non-linear dynamic response of spur gears. The multibody model is based on a penalty contact formulation and considers teeth as separated bodies elastically attached to the main body with revolute joints. One of the advantages of this model is that there is no need to use, as a source of excitation, external variables as, for example, time-varying mesh stiffness, and static transmission error input. Moreover, the computational time is reduced if compared to a finite element method (FEM) model. The modelling strategies are preliminary described in detail and a novel analytical procedure for the identification of the elastic parameters is included. A FEM model is used for testing the gears response in quasi static conditions. This preliminary comparison allows to evaluate the accuracy of the estimated stiffness values. After that, dynamic conditions varying the mesh frequency have been introduced to simulate the non-linear behaviour caused by the contact loss at certain rotating speeds. The dynamic transmission error, computed on the basis of the proposed methodology, has been successfully compared with experimental data available in literature.

This investigation focuses on the relative motion of a force-closure higher pair mechanism, herein termed caged-roller joint and composed of a cylindrical roller meshing with two slot profiles, carved on different bodies. A distinctive feature of such a mechanism is the pure rolling velocity constraint imposed between its components to limit friction losses. This makes the caged-roller joint an ideal candidate to control the kinematics of high-speed operating devices, such as centrifugal pendulum vibration absorbers. In this paper, a theoretical framework for the motion of caged-roller joint is proposed, employing intrinsic geometry, higher-path curvature and envelope theory. For design-analysis purposes, the correlations between instantaneous invariants, slots profiles curvature properties and pure rolling conditions within the higher pairs have been established. Eventually, the obtained results have been verified for three particular curves profiles, to test their consistency and offer an immediate application.

This paper deals with the analysis of the mechanical efficiency of the Rzeppa transmission joint through an analytical approach. The deduction of the mechanical efficiency of this joint is not very effortless. This kind of joint is characterized by many hyperstaticities due to the numerous contacts involved. For this reason, it represents, from the simulation point of view, a very challenging task. In this paper, an analytical approach based on the deduction of the equilibrium equation of the spheres inside the joint is proposed. By solving the deduced equations, it has been possible to predict the mechanical efficiency of the joint using only a small amount of data. This approach is very powerful in the first step of the design procedure when most of the data are unknown. The results obtained by the proposed approach, have been compared with experimental data taken from the literature. The comparison demonstrates the effectiveness of the method.

Three applications of kinematics curvature analysis are herein discussed. The first one is related to the stability of lifting rigs, the second to the design of centrifugal tautochrone dampers, and the third one to the analysis of compliant linkages.

The mechanical generation of curves is a classic topic in kinematics. Although the use of linkages for solving math problems through curve tracing is nowadays obsolete, the approximation of curves employing mechanisms maintains an industrial interest. The generalized Burmester points concept, discovered by Freudenstein in 1963, provides the theoretical background to achieve high accuracy in curve approximation for prescribed values of curvature ratios. However, the numerical computation of such points, based on the solution of a polynomial system of equations, was not without difficulty. In this paper, some developments on the kinematic of planar infinitesimal displacements are outlined. One of the progress made involves the computation of the generalized Burmester points as well as other noteworthy kinematic loci.