312 research outputs found
Le traduzioni da Brecht
No full textVengono analizzate le traduzioni da Brecht di Gabriele Mucchi, pittore, architetto e grande traduttore di poesi
Storia del Cagnolin Moz-Cova e La favola delle tre ocarine. Due manoscritti illustrati poco conosciuti di Gabriele Mucchi
No full textL\u27Album presenta i manoscritti di due racconti illustrati di contenuto satirico anti-nazista composti da Gabriele Mucchi per i propri nipoti in occasione del Natale del 1944. Le riproduzioni fotostatiche dei manoscritti si conservano nel Fondo Mucchi del Centro Apice dell\u27Università degli Studi di Milano.The Album is a presentation of the manuscripts of two illustrated stories with a satirical anti-Nazi content composed by Gabriele Mucchi for his nephews on the occasion of Christmas 1944. Xerocopies of both manuscripts are now conserved in the Fondo Mucchi of the Centro Apice at the University of Milan
On the vibro-acoustical operational modal analysis of a helicopter cabin
No full textThis paper aims to present a modal decomposition formulation for a vibro-acoustical operational modal analysis (OMA). In literature many works can be found on this topic, but until now no attention has been focused on the analytical form of the cross-power spectra (CPs) between the system outputs when a fluid-structure coupling is present. In this work it is shown that the CPs modal decomposition depends on the choice of the references, i.e. acoustical or structural. At first it is theoretically pointed out that the CP formulation for the acoustical and structural case is formally identical if appropriately pre-processed. Then, this theoretical result is verified through the results of an extensive experimental testing on the helicopter EUROCOPTER EC-135. The CPs between the structural output velocities and the acoustical response of the microphone inside the helicopter cabin are considered as inputs of an OMA. In order to verify the effectiveness of the modal model so obtained a classical modal analysis is also performed. The acoustical reference choice reveals to be suitable for a vibro-acoustical OMA. It is highlighted, indeed, that the acoustical pressure measurement inside the enclosure can be used as reference instead of the commonly used structural sensors, both from the theoretical and practical point of view. This is useful for high scale structures where the structural responses are usually measured by means of moving sensor arrays and additional fixed reference sensors should be positioned on the surface
Polarization Diversity for Multiband UWB Systems
No full textUltra-wideband (UWB) transmission provides a fast local range wireless connection using the same frequency spectrum assigned to other narrowband communication standards. A precise knowledge of the indoor transmission channel is necessary to obtain high performance. Several channel models have been presented in the literature, but normally without considering the distortion effect caused by a real UWB antenna. A detailed antenna model shows that the radiation pattern varies with frequency, i.e., different receiver positions and antenna orientations result in different antenna frequency responses. In order to obtain a more uniform coverage over the indoor area, two transmitting antennas with orthogonal polarization can be used. The receiver can use a single antenna whose orientation and position is arbitrary within the coverage area, resulting in a special case of a 2:1 MISO system in which a space-time encoding is used at the transmitter. The target is to employ the polarization diversity to obtain a constant quality of symbol detection while the receiver moves around in the coverage area. The proposed polarization diversity scheme is applied in an UWB multiband scenario and it is compared to both a single antenna scheme and a classical space diversity scheme employing a single polarized antenna arra
A new framework for Physical Layer Security in HetNets based on Radio Resource Allocation and Reinforcement Learning
No full textDensification of networks through heterogeneous cells deployment is considered a key technology to satisfy the huge traffic growth in future wireless systems. In addition to achieving the required communication capacity and efficiency, another significant challenge arises from the broadcast nature of wireless channels: vulnerability to wiretapping. Physical-layer security is envisaged as an additional level of security to provide confidentiality of radio communications. Typical characteristics of the wireless channel (noise, interference) can be exploited to keep a message confidential from potential eavesdroppers. In particular, heterogeneous networks (HetNet) have inherent security features: while the legitimate user can benefit of the HetNet architecture, the eavesdropper is strongly affected by the inter-cell interference. This paper presents an overview of HetNets intrinsic security benefits, mainly focusing on users association and resource allocation policies. In particular, allocation of radio resources is a poorly investigated topic when related to information security. However, in systems with a large radio resource reuse like HetNets, co-channel interference can be suitably exploited to resist to the eavesdropper. This paper presents a new framework for radio resources allocation using reinforcement learning (Q-learning) to increase the security level in HetNets. A coordinated scheduling among different cells using the same radio resources is proposed based on the exploitation of the spatial information. The goal is to optimize the security at physical layer. The reinforcement learning approach represents a feasible and efficient solution to the proposed problem
A Model for the Elastodynamic Analysis of the Geared Timing System of a Motorbike Engine.
No full textThis work deals with the elastodynamic model of the geared valvetrain of a four-cylinder “L” engine of a Ducati racing motorbike. The model, which is an evolution of the author’s research, is obtained as a combination of lumped parameter and finite element parts. The model is able to inspect the dynamic behaviour of both the geartrain and the cam-valve mechanisms. The paper mainly describes the model validation process that is based on several experimental tests and it is achieved by means of different steps. The information obtained from the validation stages have been finally employed for the tuning of the combined lumped/finite element model of the geared timing system. The experimental procedures are also illustrated, together with some details on the signal treatments. The comparison between simulations an experiments shows that the effectiveness of the model is satisfactorily assessed, thus permitting the use of the model as a tool for the design optimisation of the motorbike timing system. The results obtained for the competitive motorbike engine can also be utilized for common production engines, where conformity to vibration and noise standards must be fulfilled
A Non Linear Model of the Geartrain of the Timing System of the Ducati Racing Motorbike.
No full textThis work deals with the elastodynamic model of the geartrain operating the desmodromic valve trains of a fourcylinder ‘L’ engine of the Ducati racing motorbikes. The geartrain dynamic behaviour is simulated by means of a lumped parameter model which takes into account the mass moment of inertia of gears and shafts, the torsional shaft compliance, the damping effect, the parametric excitation due to the time-varying meshing stiffness, and the presence of backlash between meshing teeth. In particular, the possibility of tooth contact on both contact lines is included in the model. The comparison between numerical results and experimental measurements shows that the effectiveness of the model is satisfactorily assessed. The model allows the prediction and interpretation of the actual dynamic behaviour of the system, so to be used in design optimisation of the geartrain
Variability in Composite Structure Vibration Measurement and Numerical Model Updating
No full textThis paper presents an overview of the composite engineering projects. Research objectives,
scope of the performed tests, computational activities and main project results will be highlighted.
The main goal of this multidisciplinary projects is to investigate the dynamic properties of fibre
reinforced composite structure. Non-destructive experimental and numerical simulation methods
were applied. The test results were used in two ways: for the identification of the mechanical
properties of the structure and for non- deterministic updating the Finite Element Model according
to range of experimental models obtained from test. In the experimental part the different test
configurations were taken into account. The sources of the test data variabilities were the
excitation and measurement technique applied for investigated object. The former was performed
by means of the random and harmonic, single and multi point excitation while the latter was
contact and non-contact acceleration and velocity measurement. Non deterministic model
updating and verification & validation included uncertainties of its parameters by means of interval
and stochastic methods. An optimisation technique for test (sensor number and location) was
applied. A number of variable test modal models were statistically assessed to investigate impact
of variability source onto modal model parameters
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