491 research outputs found
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Lowering the pirate flag: a TPB study of the factors influencing the intention to pay for movie streaming services
The launch of several movie streaming services has raised new questions about how online consumers deal with both legal and illegal options to obtain their desired products. This paper investigates the factors influencing consumers’ intentions to subscribe to online movie streaming services. These services have challenged the dramatic growth in their illegal counterpart in recent years. Taking the theory of planned behavior as a starting point, we extended existing models in the literature by incorporating factors that are specific to consumer behavior in this particular field. A quantitative survey was conducted for the Italian market, and structural equation modeling was used for data analysis. Attitudes, involvement with products, moral judgement and frequency of past behavior were found to be the most important factors in explaining the intention to pay for movie streaming services. The paper provides insights for policy makers and industry managers on the marketing communication strategies needed to minimize the risk of digital piracy
Exploring the Adoption of Service-Dominant Logic as an Integrative Framework for Assessing Energy Transitions
Energy transitions (ETs) can solve some societal problems but must transform societies. Accordingly, socio-technical transitions and other systemic frameworks have been used to assess ETs. However, based on these frameworks, assessments miss a value co-creation orientation, the focus on actors' researched benefits and enabled service exchange, and the consideration of needed de/re-institutionalization practices. Analyzing those elements could prevent socioeconomic shocks and loss of opportunities and unfold possible ET challenges against ET viability and sustainability. Intending to develop a theory synthesis work for enriching previous frameworks, we propose service-dominant logic (S-D logic) as an integrative framework to assess ETs. We offer a literature review on ET systems' frameworks to compare them with the proposal. We also identify the implications of adopting S-D logic for rethinking energy systems' dynamics and ETs. Thus, we contribute to the literature by providing an integrative framework for assessing ETs and we illustrate its potentialities by deriving some challenges of the current Italian ET. This study paves the way for deeper analyses on the contribution of S-D logic to ETs and the operationalization of other systems' frameworks in our integrative one. Merging with quantitative models could also follow
Knock Detection in SI Engines by Using the Discrete Wavelet Transform of the Engine Block Vibrational Signals
Abstract In the present work, the Discrete Wavelet Transform (DWT) has been applied on the vibrational signals acquired by an accelerometer placed on the cylinder block of a Spark Ignition (SI) engine, for detecting knock phenomena. In order to collect both vibrational data and in-cylinder pressures, useful for the analysis, a series of experiments on a four cylinder, four stroke Internal Combustion (IC) engine has been carried out. The obtained results show how the presented knock detection algorithm is able to monitor the goodness of the combustion phase in absence of knock phenomena, and otherwise to determine its intensity. This algorithm uses a Multi-Resolution Analysis (MRA) performed on the vibrational signals of the engine block as acquired. The same kind of analysis has been executed by using the traditional index MAPO, which is widely applied on the pressure data, and the results of the two methods have been compared. The comparison, showing how the results are very similar, confirm that the use of the DWT represents a very valid alternative to the traditional knock detection techniques
sound quality analysis of the powertrain booming noise in a diesel passenger car
Abstract Among many noises which can be heard inside a car, the booming noise caused by powertrain excitation is usually considered as one of the very annoying acoustic features that affect the interior sound quality of a car. This work presents results coming from an experimental analysis carried out on a Diesel passenger car in order to evaluate the interior booming sensation related with the engine rotation and firing. Tests were performed in acceleration conditions on the vehicle installed at the chassis dynamometer, by measuring noise at the driver and passengers' positions inside cabin. A waterfall analysis was firstly carried out to see the spectral and temporal pattern of recorded time-varying sounds. In particular, the change of sound level related to the fundamental frequency of engine firing and its harmonics was assessed as a function of engine revolution per minute at each microphone location. Acquired data were properly post-processed for sound quality analysis as well, in order to have information about the degree of booming sensation in the accelerating car and to quantify the level of annoyance perceived by each car's occupant. The analysis allowed to identify the vehicle operating conditions as well as the locations inside cabin that make the passengers more exposed to the booming phenomenon. The obtained results represent a useful starting basis for selecting the most appropriate noise and vibration control strategies in vehicle sound quality optimization process
AN INNOVATIVE VISCOELASTIC TREATMENT FOR THE INTERNAL NOISE REDUCTION IN A REGIONAL AIRCRAFT
The improvement of interior comfort is becoming an increasingly required target in the transport engineering field, with particular attention to the aviation one. Generally, an aircraft is affected by several noise sources, from the engine power unit to the broadband components, related to the turbulent boundary layer (TBL). In this contest, the leading industries, in cooperation with research centers and universities, are actually employed in the development of innovative passive/active solutions for the internal noise as well as vibrations control: such technological implications must, on the one hand, satisfy these design requirements as well as meet the current airworthiness regulations. The paper deals with the vibro-acoustic testing activity on a typical turboprop fuselage subjected to different external load conditions: the damping ratio and the transmission loss characterization has been performed for several materials, including two innovative viscoelastic treatments too. The results highlighted a very good behaviour of the novel viscoelastic foams in terms of both acoustic and thermal performance when compared to standard blanket supported by extra viscoelastic treatments offering a very interesting self-embedded solution with a good weight to performance ratio
ANALYTICAL AND NUMERICAL MODELS FOR THE AERODYNAMIC NOISE PREDICTION OF AN HIGH-SPEED TRAIN PANTOGRAPH
The present work deals with the aeroacoustic analysis
of a three-dimensional pantograph model, through the employment of
an innovative analytical approach and a 3D numerical modeling.
Specifically, the proposed analytical approach, aimed to predict
the noise emission, is based on a modified formulation of the Smith
and Chow's formula. Namely, by considering the entire landing gear
structure as a sum of cylindrical elements, each cylinder noise has
been individually calculated by the formula, as a result, based on the
superposition principle, the whole noise is obtained; considering that
the pantograph can also be considered as a sum of cylindrical
elements, this formula, initially developed for aircraft landing gears,
has been optimized and calibrated for the purpose of the present
study.
Because of, the analytical formula does not take obviously into
account several effects related to the noise generation mechanism, a
3D numerical aeroacoustic model of the pantograph was needed.
Specifically, the theoretical background adopted is the Williams and
Hawkings acoustic analogy, an evolution of the well-known Lighthill
acoustic analogy. The latter consists in the substitution of the noise
generating surface with a distribution of dipole punctual sound
sources, whose intensity is proportional to the temporal variation of
fluid dynamic quantities acting in that point. As a result, a more
detailed characterization of the noise spectrum can be provided.
The analytical and numerical results have been then compared in
terms of sound pressure levels and a well spectral contents, to
themselves and to available experimental data
Experimental and numerical assessment of innovative damping foams
The automotive industry is currently experiencing relevant technology changes in the design of the engines, transmission and total drivetrain, induced by increasing customer demand for fuel efficiency and more stringent government requirements in emissions and safety. One of the problems relating to environmental impact concerns the noise emitted by the vehicle, for which various solutions have been experimented: new and more resistant materials have been worked out in order to minimize noise pollution and the environmental impact of the vehicle, even at the end of the operating life of its components. This research illustrates a solution as a response to those requirements, as well as being a response to the targets of comfort: a viscoelastic material, appointed to increase the damping of structures involved in vibroacoustic phenomena generated in a vehicle. The performance of these innovative materials have been analyzed both from a numerical standpoint that experimental. Starting from the empirical results of tests carried out in the laboratory, finite element models have been developed in order to have a suitable numerical database for further vibro-acoustic simulations
Automotive Materials: An Experimental Investigation of an Engine Bay Acoustic Performances
Abstract In this work an extensively experimental analysis aimed to verify the sound insulation properties of the engine bay of a commercial passenger car is carried out, evaluating the possibility to adopt different sound absorbing materials, to be applied under engine cover nylon skin, in the place of commonly used polyurethane foams. Experimental tests were performed on the vehicle at different stationary operating conditions, employing typical pressure microphones for far field measurements, according to the related prescribed standards. A limited number of materials has been initially selected through a preliminary analysis, and then employed for creating different engine cover configurations, which were subsequently tested in real engine operating conditions. For a good understanding of the obtained results, an experimental investigation through an innovative in situ impedance method aimed to assess acoustic properties of each considered material has been also performed. Among all the tested materials, only one able to ensure better acoustic performance at mid and high frequencies with respect to the already existing cover configuration, has been finally identified, after considering other selection criteria such as an adequate high temperature resistance and the most cost-effective solution. Future analyses will regard investigations on the use of additional materials, for solving problem in attenuating engine noise also at low frequencies
Sensitivity Analysis and Correlation Experimental/Numerical FEM-BEM for Noise Reduction Assessment of an Engine Beauty Cover
Abstract In this paper a deep analysis on an internal combustion engine's beauty cover is carried out for identifying the best material for Noise Reduction improvements.The paper is organized as follows: • Experimental modal analysis and comparison with the FEM simulation • Experimental test on Noise Reduction assessment by using a novel experimental set up with a Pressure/Velocity Sound Intensity • Numerical Boundary Element Analysis for computing the Noise Reduction on the engine cover • Comparison between the experimental and BEM simulation The comparison of the experimental and FEM/BEM analysis results show a very good agreement in all investigated frequency range. The obtained results encourage to use the numerical model for further investigations aimed at the improvement of the acoustic performances. The implemented numerical procedure can be applied successfully not only in automotive field but also in all problems where material acoustic performances is due
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