On line estimation of rolling resistance for intelligent tires

The analysis of a rolling tire is a complex problem of nonlinear elasticity. Although in the technical literature some tire models have been presented, the phenomena involved in the tire rolling are far to be completely understood. In particular, small knowledge comes even from experimental direct observation of the rolling tire, in terms of dynamic contact patch, instantaneous dissipation due to rubber-road friction and hysteretic behavior of the tire structure, and instantaneous grip. This paper illustrates in details a new powerful technology that the research group has developed in the context of the project OPTYRE. A new wireless optical system based on Fiber Bragg Grating strain sensors permits a direct observation of the inner tire stress when rolling in real conditions on the road. From this information, following a new suitably developed tire model, it is possible to identify the instant area of the contact patch, the grip conditions as well the instant dissipation, which is the object of the present work

Energy exchange between nonlinear oscillators: An entropy foundation

In the field of vibrations of complex structures, energy methods like SEA and a series of mid-frequency methods, represent an important resource for computational analysis. All these methods are based in general on a linear formulation of the elastic problem. However, when nonlinearities are present, for example related to clearance or stiffening of joints, these methods, in principle, cannot be applied. This paper, on the basis of a theory presented recently by one of the authors, proposes a foundation of a new energy method able to deal with nonlinearities when studying the energy exchange between subsystems. The idea relies on the concept of a thermodynamic vibroacoustic temperature, that can be directly defined when introducing the entropy of a vibrating structure. The theory is introduced in general, and examples of calculation of the power flow between nonlinear resonators are presented introducing stiffening and clearences for systems with many degrees of freedom

Prototyping a new car semi-active suspension by variational feedback controller

New suspension systems electronically controlled are presented and mounted on board of a real car. The system consists of variable semi-active magneto-rheological dampers that are controlled through an electronic unit that is designed on the basis of a new optimal theoretical control, named VFC-Variational Feedback Controller. The system has been mounted on board of a BMW Series 1 car, and a set of experimental tests have been conducted in real driving conditions. The VFC reveals, because of its design strategy, to be able to enhance simultaneously both the comfort performance as well as the handling capability of the car. Preliminary comparisons with several industrially control methods adopted in the automotive field, among them skyhook and groundhook, show excellent results

A multisensing setup for the intelligent tire monitoring

The present paper offers the chance to experimentally measure, for the first time, the internal tire strain by optical fiber sensors during the tire rolling in real operating conditions. The phenomena that take place during the tire rolling are in fact far from being completely understood. Despite several models available in the technical literature, there is not a correspondently large set of experimental observations. The paper includes the detailed description of the new multi-sensing technology for an ongoing vehicle measurement, which the research group has developed in the context of the project OPTYRE. The experimental apparatus is mainly based on the use of optical fibers with embedded Fiber Bragg Gratings sensors for the acquisition of the circumferential tire strain. Other sensors are also installed on the tire, such as a phonic wheel, a uniaxial accelerometer, and a dynamic temperature sensor. The acquired information is used as input variables in dedicated algorithms that allow the identification of key parameters, such as the dynamic contact patch, instantaneous dissipation and instantaneous grip. The OPTYRE project brings a contribution into the field of experimental grip monitoring of wheeled vehicles, with implications both on passive and active safety characteristics of cars and motorbikes

High-frequency cyclicity in the Mediterranean Messinian evaporites: evidence for solar-lunar climate forcing

The deposition of varved sedimentary sequences is usually controlled by climate conditions. The study of two Late Miocene evaporite successions (one halite and the other gypsum) consisting of annual varves has been carried out to reconstruct the paleoclimatic and paleoenvironmental conditions existing during the acme of the Messinian salinity crisis, ~ 6 Ma, when thick evaporite deposits accumulated on the floor of the Mediterranean basin. Spectral analyses of these varved evaporitic successions reveal significant periodicity peaks at around 3-5, 9, 11-13, 20-27 and 50-100 yr. A comparison with modern precipitation data in the western Mediterranean shows that during the acme of the Messinian salinity crisis the climate was not in a permanent evaporitic stage, but in a dynamic situation where evaporite deposition was controlled by quasi-periodic climate oscillations with similarity to modern analogs including Quasi-Biennial Oscillation, El Ni\~no Southern Oscillation, and decadal to secular lunar- and solar-induced cycles. Particularly we found a significant quasi-decadal oscillation with a prominent 9-year peak that is commonly found also in modern temperature records and is present in the contemporary Atlantic Multidecadal Oscillation (AMO) index and Pacific Decadal Oscillation (PDO) index. These cyclicities are common to both ancient and modern climate records because they can be associated with solar and solar-lunar tidal cycles.Comment: 13 pages, 10 figures, 1 Tabl

Processing of logical-physical rules in the control of the autonomous vehicle

Recent advances in intelligent vehicles imply more sophisticated control laws. The standard concept of objective function and models of vehicle and driver represented by differential equations, are not anymore sufficient tools in a future scenario. The capability of reasoning of the machines imposes the use of logic as a fundamental tool to describe requirements of the behavior of the vehicle, and to characterize their response. However, logical statements exhibit a difficulty of integration with the differential physic laws to which the vehicle obeys. There is a clear heterogeneity between mathematics and logic, especially when they must fuse into a single model. The paper proposes an integrated model in which the physics and the logic fuse into a common model, able to generate a meaningful objective function to optimize the behavior through a physical-logic model of the vehicle in the context of control of hybrid dynamical systems. Not negligibly, a logic-statement design helps the autonomous driving to be more acceptable and comprehensible in an insurance and court law context

Hydroxyapatite nanocrystals as a smart, pH sensitive, delivery system for kiteplatin

Hydroxyapatite (HA) nanocrystals are important inorganic constituents of biological hard tissues in vertebrates and have been proposed as a bone substitute or a coating material for prostheses in biomedicine. Hydroxyapatite is also amenable for its capacity to bind to a great variety of biomolecules and therapeutic agents. As drug carriers, apatite nanoparticles also have the advantage of pH dependent solubility and low toxicity. Thus HA nanoparticles are negligibly soluble at physiological pH but their dissolution is accelerated at lower pH such as that typically found in the vicinity of tumors. In the present study we have investigated the adsorption on and the release from biomimetic HA nanoparticles of two platinum derivatives of cis-1,4-diaminocyclohexane ([PtX2(cis-1,4-DACH)], X2 = Cl2 (1) and 1,1-cyclobutanedicarboxylate (CBDCA, 2)). The first of the two compounds proved to be active against colon cancer cells also resistant to oxaliplatin. The release has been investigated as a function of pH to mimic the different physiological environments of healthy tissues and tumors, and the in vitro cytotoxicity of the releasates from the HA matrices has been assessed against various human cancer cell lines. The results fully confirmed the potential of 1-loaded HA nanoparticles as bone-specific drug delivery devices

The Messinian salinity crisis: open problems and possible implications for Mediterranean petroleum systems

Abstract: A general agreement on what actually happened during the Messinian salinity crisis (MSC) has been reached in the minds of most geologists but, in the deepest settings of the Mediterranean Basin, the picture is still far from being finalized and several different scenarios for the crisis have been proposed, with different significant implications for hydrocarbon exploration. The currently accepted MSC paradigm of the ‘shallow-water deep-basin’ model, which implies high-amplitude sea-level oscillations (> 1500 m) of the Mediterranean up to its desiccation, is usually considered as fact. As a consequence, it is on this model that the implications of the MSC events on the Mediterranean petroleum systems are commonly based. In fact, an alternative, deep-water, non-desiccated scenario of the MSC is possible: it (i) implies the permanence of a large water body in the Mediterranean throughout the entire Messinian salinity crisis, but with strongly reduced Atlantic connections; and (ii) envisages a genetic link between Messinian erosion of the Mediterranean margins and deep brine development. In this work, we focus on the strong implications of an assessment of the petroleum systems of the Mediterranean and adjoining areas (e.g. the Black Sea Basin) that can be based on such a non-desiccated MSC scenario. In particular, the near-full basin model delivers a more realistic definition of Messinian source-rock generation and distribution, as well as of the magnitude of water-unloading processes and their effects on hydrocarbon accumulation

Unsupervised identification of damage and load characteristics in time-varying systems

Abstract Parameters identification of nonstationary systems is a very challenging topic that has only recently received critical attention from the research community. Aim of the paper is the structural health monitoring of bridge-like structures excited by a massive moving load, whose characteristics, such as the mass and speed, are unknown, in the presence of a localized damage along the structure

Energy Distribution In Impulsively Excited Structures

This paper presents a novel approach to the study of shock in elastic structures. An energy storage property for linear elastic non-dissipative structures is demonstrated, then extrapolated also to damped systems. This property relates locations of energy accumulation along the structure to the form of its stiffness and mass matrices. This result can be profitable used at a design stage of complex structures undergoing shock excitations. On the theoretical ground, the obtained results disclose indeed general properties of energy distribution in dynamical systems with implications on energy localization as well as on energy equipartitioning Finally, these findings open a new point of view on energy transmission in structures, with potential application in the context of Statistical Energy Analysis