F. Resta's research while affiliated with Politecnico di Milano and other places

Publications (118)

Conference Paper
The aim of active vibration control is to enhance the performance of a system (eg. comfort, fatigue life, etc.) by limiting vibrations. 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). Application of ac...
Conference Paper
Even with travelling speeds below 200 km/h, typical features of freight trains, such as the poor aerodynamic performances due to wide and squared surfaces or the presence of empty vehicles alternate to loaded ones, can remarkably worsen the effects of interaction with wind. Aim of the work is to highlight the worst compositions in terms of rollover...
Article
Vibration control logics based on the modal approach allow damping to be increased on a certain number of modes. The main limit associated with these strategies is represented by spillover on non-modelled modes. Negative derivative feedback (NDF) proves particularly robust against spillover since modal velocity is fed back through a band-pass filte...
Article
Optical strain gauges, such as Fiber Bragg Grating (FBG) sensors, are widely used to monitor the health of structures and their state of deformation. This paper proposes exploiting the measurements of these sensors as feedback for active vibration control applications. The advantages of this solution are the possibility of monitoring a large number...
Article
One of the most common applications of active control on flexible structures is the mitigation of vibrations to reduce stresses and consequently increase lifetime. However, except for a few particular cases, the fatigue phenomenon has never been taken into account in the design of the control algorithm. Moreover, since fatigue is mainly a local eff...
Article
Embedding FBG sensors in carbon fiber structures is a very attractive procedure, due to the small fiber cross section and to the possibility of manufacturing arrays of many gratings into a single optical fiber. This embedding is particularly useful for the manufacturing of smart structures, enabling improvement of their characteristics thanks to th...
Article
During recent decades safety in the workplace has become more and more important. For this reason, systems for the diagnosis of possible failures represent a particularly attractive solution. In this paper a health monitoring algorithm for a specific kind of construction machinery (concrete displacing booms) is proposed. It is based on the knowledg...
Article
Many systems have, by their nature, a small damping and therefore they are potentially subjected to dangerous vibration phenomena. The aim of active vibration control is to contain this phenomenon, improve the dynamic performance of the system, and increase its fatigue strength. A way to reach this goal is to increase the system damping, preferably...
Article
Full-text available
This paper presents a new control technique for reducing vibration in flexible structures. It is based on the modal approach and is called dependent modal space control (DMSC). The well-known independent modal space control (IMSC) method, devised in the 1980s, allows the frequency and damping of the controlled modes to be changed using diagonal con...
Chapter
The present paper deals with the development of a bench for testing prostheses for legs. The bench includes a fake leg (from femur to foot) and it allows rotations of femur (up to 40°) and of tibia with respect to femur (up to 40°). Lockable gas springs allow stopping tibia and femur rotations. An hydraulic actuator applies a load to the hip, while...
Conference Paper
Fiber Bragg Gratings (FBG) sensors have a great potential in active vibration control of smart structures thanks to their small transversal size and the possibility to make an array of many sensors. The paper deals with the opportunity to reduce vibration in structures by using distributed sensors embedded in carbon fiber structures through the so...
Conference Paper
The large use of lightweight structures has emphasized the need to reduce undesired vibrations which can compromise the integrity and the safety of flexible structures. The advancements in materials technology have made available a new generation of materials regarded as smart. Thanks to the results obtained in this field, many research are focusin...
Conference Paper
In Active Vibration Control of smart structures, the actuator and sensor placement is a key point of the control system design. The objective of this paper is to propose an H2 norm approach for the actuator and sensor placement, which aims not only to maximize the norms of the controlled modes but also to reduce spillover problems by taking into ac...
Conference Paper
During the last decades, in order to reduce the vibrations in flexible structures, many active control strategies have been introduced. Among the other techniques, adaptive active controls are particularly attractive for time-varying and nonlinear systems. The goal of this work is to propose an adaptive version of Direct Velocity Feedback (DVF) usi...
Conference Paper
Full-text available
This paper presents a new control technique for vibration reduction based on modal approach and named Dependent Modal Space Control (DMSC). It is an active control logic that allows to assign the closed loop poles and the corresponding mode shapes of a system in a discrete number of degree of freedom depending on the amount of the sensors and actua...
Article
In active vibration control of smart structures, the actuator and sensor placement is a key point of the control system design. Even the most robust control logics could easily make a structure unstable if the actuators and sensors were not correctly positioned. The objective of this paper is to propose an H2 norm approach for the actuator and sens...
Conference Paper
The laws concerning safety on worksite have become more strict year on year being that topic always more important. The main causes of injuries are workers unawareness and structural failures of machineries, i.e. cranes, or scaffolds. In order to prevent injuries, an accurate maintenance is mandatory. During the last years a new trend in maintenanc...
Article
In this paper a resonant control technique, called negative derivative feedback (NDF), for structural vibration control is presented. Resonant control is a class of control logics, based on the modal approach, which calculates the control action through a dynamic compensator in order to achieve a damping increase on a certain number of system modes...
Article
Magnetostrictive inertial actuators are profitably used in applications of vibration control. However their use is limited to high frequencies because of problems related to control stability and to small exertable forces. This paper presents the design of an innovative low-frequency magnetostrictive inertial actuator. With respect to traditional m...
Article
Full-text available
In this work the methodology and the calibration procedure of a wheel-set properly instrumented to measure the wheel-rail contact forces is presented. The calibration is performed on a non-rolling bench on which a complete bogie is mounted in order to impose the correct constraint conditions to the wheel-set. The contact forces on the wheels of the...
Article
Concrete pump booms are subjected to vibrations that increase mechanical stress and shorten their lifespan.This paper aims to study the problem by considering the two subsystems, the boom and the concrete pump, that have the greatest effect on the phenomenon. The authors supply numerical and experimental tools that can analyze the problem in depth...
Article
This paper presents a control strategy for the suppression of vibration due to unknown disturbance forces in large, nonlinear flexible structures. The control action proposed, based on the modal approach, consists of two contributions. The first is the well-known Independent Modal-Space Control, which increases system damping and improves its behav...
Article
This paper presents an active control logic for vibration suppression in flexible structures. This control logic, called Active Modal Tuned Mass Damper, is based on an active realization of the passive mechanical Tuned Mass Damper. Starting from the traditional TMD theory, a closed loop formulation is proposed to calculate the active control force....
Article
Concrete placing booms are subjected to vibrations that increase mechanical stress and reduce the boom's working life. The aim of this paper is to develop an active control methodology to suppress boom vibrations using the same actuators that produce the large motion of the boom. The control logic is based on two contributions, a feedforward and a...
Chapter
Concrete placing booms are subjected to vibrations causing an increase of mechanical stress and a reduction of the boom lifetime. The aim of this paper is the development of an active control methodology in order to suppress boom vibrations using the same actuators performing the boom large motion. The control logic is based on two contributions, a...
Chapter
This paper describes a study of the behavior of a “truck-mounted concrete pump” used industrially to pump large quantities of concrete. The characteristics of the pump, its functioning and its numerical model will be explained. Numerical model results will be compared with experimental ones. The paper demonstrates, using the mathematical model, how...
Article
Full-text available
Concrete pump booms are subjected to vibrations that increase mechanical stress and shorten their lifespan. This paper aims to study the problem by considering the two subsystems, the boom and the concrete pump, that have the greatest effect on the phenomenon. The authors supply numerical and experimental tools that can analyze the problem in depth...
Article
Full-text available
The independent modal control to suppress the vibration of nonlinear flexible structures is applied in this paper. Technological improvements in the mechanical field showed during the recent years have led to high-performance systems with low weight and, as a consequence, high flexibility and low damping. Here active control quickly bettered the tr...
Article
Full-text available
In this paper an active modal TMD control logic for the vibration suppression is presented. Starting from the traditional TMD theory, a closed loop formulation is proposed to calculate the active control force. The possibility to describe every mechanical systems or civil structures with a set of modal coordinates allows to act independently on eac...
Conference Paper
Instrumented wheelsets have been used for years to assess running safety of railway vehicles. International Standards (EN 14363 [1]) prescribe a complete testing procedure for the approval of a new vehicle. As far as running safety is concerned, the sum of the guiding forces in straight track (ΣY) and the derailment coefficient (Y/Q) in curve must...
Article
One of the most frequent applications of magnetostrictive actuator technology is the active structural vibration control (AVC). Magnetostrictive actuators (MAs) can deliver high-output forces and can be driven at high frequencies. These characteristics make them suitable for a variety of vibration control applications. The use of this technology, h...
Article
Inertial actuators are widely used device in active vibration control applications. The aim of the paper is to analyze the limits on the use of such devices in terms of stability when fully active skyhook damping control is implemented. Different control strategies are investigated and numerical simulation are led considering different vibrating me...
Article
This paper investigates the use of independent modal control to suppress the vibration of nonlinear flexible structures. In recent years technological improvements in the mechanical field have led to high-performance systems with low weight and, as a consequence, high flexibility and low damping. Here active control quickly bettered the traditional...
Conference Paper
Full-text available
This paper presents semi-active control of wind-induced vibrations in tall buildings using MR dampers. The dampers are implemented using both internal and outer bracing systems to reduce the response of the building in the two lateral directions for both structural safety and human comfort concerns. MR dampers with internal bracing system are shown...
Article
High-rise buildings can experience large across-wind response due to the vortex excitation generated by the detached flow around the bluff-body. The capability to predict this motion is fundamental for design purpose and occupancy comfort evaluation. Once the wind loads are known, for instance by wind tunnel tests on rigid models, the tower respons...
Article
A new approach to deal with aerodynamic non-linearities in time domain has been developed using a rheological mechanical model. The parameters of the rheological model have been estimated from specific wind tunnel tests. Once identified, the rheological system allows to reproduce the aerodynamic forces, starting from the bridge motion and the wind...
Article
Progressive multifocal leukoencephalopathy (PML) is a fatal neurological disease affecting the central nervous system. JC polyomavirus is the agent related to this disease. PML usually occurs in patients with HIV infection or other immunodeficiencies. We report a case of PML in a patient with idiopathic CD4+ cells deficit. The symptoms began with r...
Article
The operation of high-speed trains requires higher performance of the pantograph–catenary dynamic interaction, in order to ensure a satisfactory quality of the current collection. Both numerical and experimental approaches are available to assess the dynamic performance of a pantograph coupled with a catenary. In order to reduce the duration of in-...
Conference Paper
Full-text available
Developments in structural materials have led to designs that satisfy strength requirements but are often very flexible. Wind loads and the associated structural responses are a governing factor in the design of the steel framing system of many high-rise buildings. Wind load capacity is also a key factor in determining the overall strength of tower...
Conference Paper
Full-text available
This paper presents a detailed study to investigate the influences of incident wind direction, upstream terrain conditions and interferences from the surroundings on the wind responses of a tall building. The tower considered in this study represents a high-rise building that is to be constructed in the city of Milan, Italy. The outer dimensions of...
Conference Paper
In the present paper an alternative way to apply active control on a high speed train pantograph is proposed. The control is based on two main concepts: the use the incident air flow on the pantograph as power source, and the application of the control force directly on the collector, i.e. where it is immediately required for the modification of th...
Conference Paper
Active/semi-active suspension systems are getting widely accepted for their potential to improve ride comfort of passenger cars with respect to traditional suspension systems. A feedback controller has been designed allowing to control separately the vehicle body motions of heave, pitch and roll taking into account the dynamics of the active/semi-a...
Article
Approximately 20-25% of patients with limited small cell lung cancer (SCLC) can be cured with an aggressive approach (chest radiation concomitant with chemotherapy) followed by prophylactic cranial irradiation (PCI) to a total dose of 30-36Gy with 3-2Gy per fraction, five fractions per week. Steroid prophylactic therapy with dexamethasone is usuall...
Article
As train speed increases, contact wire irregularity affects the quality of current collection more and more. The possibility of achieving the maximum operating speed depends also on the maintenance level of the overhead line (OHL). In the present paper, the influence of contact wire irregularity (in terms of vertical deviation of its position) is i...
Conference Paper
The paper describes a research project being performed by RFI (Italian track owner) and Politecnico di Milano concerning the diagnostics and condition monitoring of the railway track and overhead equipment. The program aims particularly at increasing the availability of precise information concerning the maintenance status of the line both by intro...
Article
Usually measles is not severe, but serious complications can occur and thus hospitalization is needed. The aim of this study was to assess the reasons of hospitalizations of the persons affected by measles and the severity of disease as a result of measles infection. During an outbreak from 2002 to 2003 in the province of Taranto, 73 hospitalized p...
Conference Paper
MEMS sensors usually work at frequencies well above 1kHz. At these frequencies, supporting beams do not only contribute to the elasticity of the system but also to its inertia. However, the supporting beams’ inertia is not equal to any modal mass since excitation frequency is not equal to any eigenfrequency of the supporting beams. Based on a FEA m...
Conference Paper
Except for MEMS working in ultra high vacuum, the main cause of damping is the air surrounding the system. When the working pressure is equal to the atmospheric one (from now on called "high pressure", i.e. 105Pa), the mean free path of an air molecule is much smaller than typical MEMS dimensions. Thus, air can be considered as a viscous fluid and...
Article
Vortex-induced vibrations are not negligible while evaluating the aerodynamic and aeroelastic behavior of a long-span suspension bridge. This kind of forcing, that can produce high vibration levels, occurs at very low reduced velocities concerning low wind speed and high-frequency modes. This work presents results of experimental tests performed on...
Conference Paper
The current collection for the traction motor of trains is obtained by means of a sliding contact between the overhead line (OHL) and the collector strips mounted on the pantograph head. As the train speed increases, the variation of contact force exchanged between the pantograph and the OHL, dependent on their dynamic interaction, becomes greater....
Article
Some aspects about the influence on the current collection of the aerodynamic action on a pantograph, due to the incoming flow generated by train speed are investigated considering pantograph–catenary dynamic interaction. Starting from the quasi-steady theory formulation of the drag and lift forces on the collectors, and considering the turbulence...
Article
The analysis of runnability of railway bridges is one of the tasks related to high speed trains since it involves the dynamic response of a bridge crossed by a train. In the proposed paper the runnability analysis has been carried out by means of numerical simulation based on mathematical model of train-track-bridge interaction developed in previou...
Article
Although VDC systems usually operate on the engine torque and on brake pressures [Van Zanten, A.T., Erhardt, R. and Pfaff, G., 1995, VDC, The Vehicle Dynamics Control System of Bosch. SAE Technical Paper Series, no. 950759, Esmailzadeh, E., Goodarzi, A. and Vossoughi, G.R., 2003, Optimal yaw moment control law for improved vehicle handling. Mechatr...
Article
Hepatitis C virus (HCV) variability is mainly attributed to the ability of the virus to respond to host immune pressure, acting as a driving force for the evolution of quasispecies. This study was aimed at studying the changes in HVR-1 heterogeneity and the evolution of HCV quasispecies in HIV/HCV-coinfected patients according to the pattern of res...
Article
Full-text available
Background. We obtained estimates of the incidence of tuberculosis (TB) among patients receiving HAART and identified determinants of the incidence. Methods. We analyzed the incidence of TB during the first 3 years after initiation of HAART among 17,142 treatment-naive, AIDS- free persons starting HAART who were enrolled in 12 cohorts from Europe a...
Conference Paper
When significantly displacing a proof mass, the nonlinear hardening characteristic of the supporting beams becomes visible. Thus, the resonance peak of the structure is no longer vertical but bends towards the higher frequencies. This property is useful to easily synchronise sense and drive resonances thus increasing the sensibility of the MEMS dev...
Article
Although the secondary transmission of hepatitis A virus (HAV) infection is preventable through vaccination, it is not known whether the vaccination of household contacts is feasible. To this end, we conducted a prospective cohort study among the household contacts, 40 years of age or less, of all persons infected with primary HAV infection (index...
Article
Evidence has been cumulated during the last years concerning the immaturity of the cells involved in the local and systemic aspects of allergic inflammation. Hematopoietic precursors (HPC) are mobilized from the bone matrix as multipotent cells or, more often, as progenitors that, after the initial white-lineage commitment reach through the periphe...
Article
A numerical physical three-dimensional (3D) tyre model namely the physical rigid-ring tyre (PaRRT) model for tyre wear prediction, validated during previous research, is used to determine those design parameters that mostly affect tyre wear. The sensitivity analysis is carried out by modifying one parameter of the physical 3D tyre model per time. T...
Article
The prognostic role of GB virus type C (GBV-C) viraemia in HIV-infected subjects treated with highly active antiretroviral therapy (HAART) is still undefined, The aim of this analysis is to assess the relationship between GBV-C infection and response to antiretroviral therapy among HIV-infected subjects initiating HAART when antiretroviral-naive. A...
Article
We examined the impact of a lamivudine-containing highly active antiretroviral therapy (HAART) regimen on 164 hepatitis B virus/HIV co-infected individuals starting their first HAART. Lamivudine-treated patients (accounting for 73% of the study population) showed a significantly lower level of alanine aminotransferase over follow-up [–81.1 mU/ml me...
Article
High level HIV-1 drug resistance in recently infected treatment-naive individuals correlates with sub-optimal virological responses to highly active antiretroviral therapy (HAART). To determine whether genotypic HIV-1 drug resistance in chronic naive patients, as interpreted by various systems, could predict the virological outcomes of HAART, isola...
Article
The work presents a new original experimental rig to more deeply investigate the aerodynamic behaviour of long span suspension bridges. Set-up and model are designed to grant an accurate study on main aeroelastic phenomena in bridge engineering. More in details, experimental set-up and a 1:60 scale sectional model of Messina bridge deck are present...
Article
An analysis refinement of the Messina Strait suspension bridge project has been recently required, concerning mainly the yaw angle effects on the multi-box deck section aerodynamics and the vortex shedding at low reduced velocities V*. In particular the possible interaction of the axial flow with the large cross beams has been investigated. An orig...
Article
Full-text available
Trains current collection for traction motors is obtained by means of a sliding contact between the overhead line (OHL) and the collector strips mounted on the pantograph head. The normal force by which the collector presses against the contact wire ensures the contact pressure for the electrical contact. As the train speed increases, the variation...
Conference Paper
The work presents a new original experimental rig to investigate more deeply the aerodynamic behaviour of long span suspension bridges. Set-up and model are designed to grant an accurate study on main aeroelastic phenomena, relevant in bridge engineering. More in details, experimental set-up and a 1:60 scale sectional model of Messina bridge deck a...
Article
The task is to determine the tyre load spectra of a truck vehicle in terms of hub forces, which will provide the input for a mathematical model for tyre wear evaluation. Two ways have been followed to reach this objective a fully experimental approach, aiming at the direct determination of the hub forces, and a mathematical one, based on multi‐body...
Article
This paper illustrates the rolling dynamic bench tests for wheel sets carried out by Lucchini S.p.A. in the Lovere plant. The utilised methodology and the possible developments are presented.
Article
The paper presents a full scale rolling plant for dynamic tests on wheel sets. The main research activities on the plant are hereby illustrated, giving a brief description and explaining their purposes. The experimental equipment is subsequently described, giving details on the relevant set-up for the measurement, during the tests, of the most inte...
Article
The paper deals with the application of active control to high speed trains. To this end, an innovative controlled electro-mechanical device was designed to substitute traditional yaw dampers currently in use. The main components of this system are a brushless motor, with gear and spindle, used to apply a longitudinal force between the carbody and...
Article
A mathematical model of a roller rig for full size tests on a railway wheelset is proposed. The model is used in order to allow optimal utilization of the testing facility and is expected to give important insights into wheel-rail contact modelling and wear mechanisms, through comparison between numerical results and experimental ones performed in...
Article
The aim of the paper is to describe and verify a numerical model for the simulation of the dynamic behaviour of a tilting body railway vehicle, with particular attention to the curve negotiation conditions. In the model the dynamics of the tilting active control devices are reproduced, combining the numerical mechanical model of the vehicle with th...
Conference Paper
Deals with the application of active control to increase the operating speed of high speed trains by avoiding the occurrence of hunting instability. To this end, an innovative controlled electro-mechanic damper was designed to substitute traditional yaw dampers currently in use. The main components of this system are a brushless motor, with gear an...
Conference Paper
An active control for a high speed train pantograph is proposed in order to improve power collection at high speed (i.e. V>220 km/h) allowing the speedup of the existing lines. The control is based on an available commercial actuator, and its feasibility and effectiveness have been investigated by means of numerical simulation. For this purpose, th...