3,108 research outputs found
Employment of an acoustic camera for noise characterisation of a laboratory equipment
No full textExposure to noise constitutes a health risk. The present paper is related to activities performed to test emerging technologies aimed to characterise noise sources. In particular, acoustic acquisitions have been achieved on a complex laboratory equipment composed by different machines including a rotor serving as blower. Advanced noise measurement techniques based on acoustic
holography and beamforming have been employed to realise a deep characterisation of the noise sources. This analysis could fix, in effective way, the possible mitigation strategies and, if extended
to the other noise sources, a comprehensive management of the workplace noise exposure
Preliminary evaluation and optimization of civil aircraft sonic-boom properties through Carlson's method
No full textIn this paper a simple approach based on the Carlson's method will be presented to define a supersonic conguration optimized in terms of sonic boom properties. The Carlson's method provides a simplified procedure for the calculation of sonic boom characteristics for supersonic airplane congurations and spacecrafts. The information required for the signature predictions
are: aircraft shape factor KS, aircraft operating conditions and atmospheric data. Unfortunately, there is not an analytic expression of the shape factor. Nevertheless, a graphic representing the relationship between KS and parameters related to the aircraft geometry, can be used. In this paper KS have been approximated through a linear and a quadratic interpolation as a function of other parameters and its minimization problem has been formulated. Computational results show the optimal values to be assigned to the aircraft geometry parameters in order to obtain the minimal value of the shape factor and in consequence of the sonic boom overpressure
Mistuning effects evaluation on turbomachine dynamic behaviour using genetic algorithms
No full textThis paper presents a new approach to evaluating the mistuning effects on turbomachinery blades that is classified
as neither deterministic nor statistical — it is based on the employment of genetic algorithms. A genetic algorithm
has been exploited to find the structurally mistuned configuration that leads to the maximum value of blade
vibration amplitude for an assigned domain of variations. A test case has been fixed and subjected to an assigned
forcing field; the target of the test case was to perform a smart search of the worst mistuned configuration. The test
case was a twenty-blade disc on which one thousand forced frequency response analyses have been performed. A
comparison with the results, based on the Monte Carlo methods, proved the suitability and the relevance of the
proposed approach. The investigation has demonstrated the applicability of this new possible engineering approach
to the study of systems with uncertain properties
Structural behaviour modelling of bolted joints in composite laminates subjected to cyclic loading
No full textThe structural behaviour of bolted joints of composite laminates for aerospace applications was modelled comparing the shape, amplitude and phase of stress–strain cycles. This study proposes a model for the bolted joints resulting in a typical load–displacement curve, under cyclic loading, significantly affected by hysteretic effects. From the data gathered through the experimental activities, a constitutive relationship between strain and stress was proposed, starting from simple physical models. The assumption of a rigid shift between the laminates was used to correlate load and displacement curves in the different phases of the load cycle. The hysteretic behaviour was attributed to friction phenomena and interpreted using damping coefficients characterizing the global dynamic response of the structural joint
Vibrational analysis of aerospace composite components for production defects and operating damage detection
No full textNon-Destructive Testing of aircraft structures is of paramount relevance leading to key information regarding the structural characteristics and the residual life of a component. This paper is focused on the experimental and modeling activities related to vibrational analysis carried out on a typical aeronautical composite sample. A flap section of a regional aircraft has been studied applying the conventional tools of the modal analysis. The aeronautical component has been at first characterized in terms of natural frequencies and normal modes. Then it has been damaged using a drop tower that induced a controlled impact in the structural component. The vibrational analyses have been repeated and the normal modes in the two conditions have been compared. Then other approaches based on vibrational properties of the structures have been investigated to detect defect and damage
Direct replacement of antibodies with molecularly imprinted polymer (MIP) nanoparticles in ELISA - development of a novel assay for vancomycin
No full textA simple and straightforward technique for coating microplate wells with molecularly imprinted polymer nanoparticles (nanoMIPs) to develop ELISA type assays is presented here for the first time. NanoMIPs were synthesized by a solid phase approach with immobilized vancomycin (template) and characterized using Biacore 3000, dynamic light scattering and electron microscopy. Immobilization, blocking and washing conditions were optimized in microplate format. The detection of vancomycin was achieved in competitive binding experiments with a HRP-vancomycin conjugate. The assay was capable of measuring vancomycin in buffer and in blood plasma within the range 0.001-70 nM with a detection limit of 0.0025 nM (2.5 pM). The sensitivity of the assay was three orders of magnitude better than a previously described ELISA based on antibodies. In these experiments nanoMIPs have shown high affinity and minimal interference from blood plasma components. Immobilized nanoMIPs were stored for 1 month at room temperature without any detrimental effects to their binding properties. The high affinity of nanoMIPs and the lack of a requirement for cold chain logistics make them an attractive alternative to traditional antibodies used in ELIS
Ethnic variation in the prevalence of depression and anxiety in primary care: A systematic review and meta-analysis.
No full textPrimary care plays a key role in the detection and management of depression and anxiety. At present it is not clear if the prevalence of depression and anxiety in primary care differs between migrants and ethnic minorities (MI) and natives and ethnic majorities (MA). A systematic review and a meta-analysis of studies comparing the prevalence of depression and anxiety in MI and MA in primary care were performed. Studies were identified by searching MEDLINE, PsychINFO, EMBASE and through hand-search. We included 25 studies, most of which had a relatively small sample size. Significant variations were found in the prevalence of anxiety and depression across studies. Pooled analyses were carried out for 23 studies, based on random-effects models. Pooled RR of depression and anxiety in MI were 1.21 (95% CI 1.04-1.40, p=0.012) and 1.01 (95% CI 0.76-1.32, p=0.971), with high heterogeneity (I2=87.2% and I2=73%). Differences in prevalence rates among studies can be accounted for by inclusion criteria, sampling methods, diagnostic instruments and study design. Further research on larger samples and with culturally adapted instruments is needed to estimate the prevalence of depression and anxiety in MI seeking help for these disorders
Coaching early career teachers in urban elementary schools: A mixed method study
No full textCoaching for urban early career teachers (ECTs) offers promise and aligns with features of effective professional development to support the implementation of evidence-based practices. However, the functional components and key elements of coaching and coach supervision are not well specified in the literature. The goal of the current study was to examine adherence and feasibility of a coaching intervention designed to provide urban ECTs with concentrated support in classroom management and engaging learners—two instructional domains that are robust predictors of attrition (Ingersoll and Strong in Rev Educ Res 81:201–233, 2011). Coaches (n = 6) worked with ECTs (n = 15) in three urban, high-poverty elementary schools during the 2-year intervention. A mixed-method design was employed, such that qualitative data (i.e., semi-structured interviews) and quantitative data (i.e., adherence measures) were collected concurrently, remained independent during analyses, and were integrated during interpretation (Creswell and Clark in Designing and conducting mixed methods research. Sage, Thousand Oaks, 2007). Findings revealed that ECTs generally received the intended frequency and duration of coaching but with fewer opportunities for post-conferences. Coach supervision, on average, was delivered with intended frequency, with variability across coaches. Thematic analyses highlighted coach provision of emotional and instrumental support, emphasized consistent coaching as critical, and that time was a significant barrier to ECT participation in coaching. Supervision promoted social support among coaches and provided opportunities to adapt the model to ECT needs.Peer reviewe
Communautés et écriture en ligne. Histoire, devenir, un dialogue
No full textIn this interview, Elisa Bricco talks to writer Benoît Vincent about
the transformations that have taken place over the last twenty years
as a result of the technological turn in literary production. We look
at the repercussions of technology’s hold over literary production, and
in particular at the development of the notion of author in the context
of collective writing. The example of the General Instin project will
be used to highlight some of the issues raised by digital technology in
relation to the production of literary texts.Dans cet entretien, Elisa Bricco discute avec l’écrivain Benoît Vincent
sur les transformations qui sont survenues dans les vingt dernières
années à cause du tournant technologique de la production littéraire. On
s’interroge sur les répercussions de l’emprise de la technologie sur le
faire littéraire et notamment sur le développement de la notion d’auteur
dans le contexte de l’écriture collective. L’exemple du projet Général
Instin servira pour mettre en lumières quelques enjeux du numérique
par rapport à la production de textes littéraires
Communautés et écriture en ligne. Histoire, devenir, un dialogue
No full textIn this interview, Elisa Bricco talks to writer Benoît Vincent about the transformations that have taken place over the last twenty years as a result of the technological turn in literary production. We look at the repercussions of technology’s hold over literary production, and in particular at the development of the notion of author in the context of collective writing. The example of the Général Instin project will be used to highlight some of the issues raised by digital technology in relation to the production of literary texts.Dans cet entretien, Elisa Bricco discute avec l’écrivain Benoît Vincent sur les transformations qui sont survenues dans les vingt dernières années à cause du tournant technologique de la production littéraire. On s’interroge sur les répercussions de l’emprise de la technologie sur le faire littéraire et notamment sur le développement de la notion d’auteur dans le contexte de l’écriture collective. L’exemple du projet Général Instin servira pour mettre en lumières quelques enjeux du numérique par rapport à la production de textes littéraires
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