A Transmission Line Model for the Calculation of Phononic Band Gaps in Perforated Mems Structures

AbstractIn this paper an acoustic transmission line model for the calculation of phononic band gaps is presented. We study the propagation of longitudinal waves in thin, rectangular perforated rods. We show that the 1D nature of the rod vibrations allows the modeling of the system by a series of acoustic transmission lines with different characteristic impedance, where the perforated section is modeled as an equivalent filled material with Young's modulus and mass density depending from the size of the holes. Once this model is defined, the derivation of the transmission matrix and transmission coefficient (in matching conditions) of the entire rod is straightforward by using the classical transmission line theory. Finally, the phononic band gap predicted by this model is verified by means of an ANSYS harmonic analysis

An analytical model for the resonance frequency of square perforated Lamé-mode resonators

In this work, simple analytical models based on the concept of an equivalent material are used to describe the mechanical behavior of resonators perforated by a regular array of square holes, a common occurrence in several MEMS devices and sensors. This description is applied to the determination of the resonance frequency of Lamé-mode square resonators, which are frequently pursued as high-Q MEMS resonators. The models predictions are compared with FEM simulations and experimental data both from the literature and from measurements obtained by the authors on thick SOI MEMS resonators. The models predictions are in good accordance both with FEM results and with experimental data

Design of Piezo-Actuated MEMS Flexural Phononic Crystals for Mass Sensing Applications

In this work, we present a method for the design of piezoelectrically actuated flexural phono-nic crystal beam devices, targeted at the development of innovative biochemical sensors in a MEMS technology. The method exploits the Timoshenko transmission matrices. The calcu-lated transmission spectra are shown to be in excellent agreement with FEM simulations

A Simple Analytical Model for the Resonance Frequency of Perforated Beams

Abstract In this work the bending properties of beams with periodic rectangular perforations are examined. Starting from the standard Euler-Bernoulli beam equation, compact analytical expressions for the equivalent bending stiffness in the filled and perforated sections are developed and used to compute the resonance frequencies of the perforated beam. The results are in good agreement with FEM simulations for most practical designs, as long as shear stress effects can be considered negligible

Modelling the joint impact of R&D and ICT on productivity: a frontier analysis approach

This study explores the channels through which technological investments affect productivity performance of industrialized economies. Using a Stochastic Frontier Model (SFM) we estimate the productivity effects of R&D and ICT for a large sample of OECD industries between 1973 and 2007, identifying four channels of transmission: input accumulation, technological change, technical efficiency and spillovers. Our results show that ICT has been particularly effective in reducing production inefficiency and in generating inter-industry spillovers, while R&D has raised the rate of technical change and favoured knowledge spillovers within sectors. We also quantify the contribution of technological investments to output and TFP growth documenting that R&D and ICT accounted for almost 95% of TFP growth in the OECD area

Product market regulation and innovation efficiency

We study the role of upstream product market regulation (PMR) in innovation efficiency. By estimating a knowledge production function on OECD industries through a stochastic frontier analysis, we find that service regulation reduces R&D efficiency in the manufacturing sector. These results are robust to controlling for the institutional setting of the technology, the labour and the financial market, and to various forms of heterogeneity. The marginal impact of PMR is higher in less regulated economies indicating that large improvements in R&D efficiency cannot be obtained at the earlier stages of deregulation. Potential efficiency gains for late reformers are however sizeable

New approach to underwater technologies for innovative, low-cost ocean observation (nautilos): operational field primary capture system

The large variety of platforms and sensors globally deployed and available, allows access to a conspicuous quantity of data and variables with heterogeneous formats and scales. In the last decades governments and the scientific world have encouraged standardizations and best practices for data collection, elaboration and distribution. Several initiatives had led the bases for globally shared practices and quality indexes. This paper aims at giving a state of the art concerning the existing best practices and quality indices of the most important platforms, initiatives and projects for the scope of NAUTILOS - New Approach to Underwater Technologies for Innovative, Low-cost Ocean observation - H2020 project (www.nautilosh-2020.eu; ct. 101000825)info:eu-repo/semantics/publishedVersio

Rehabilitation of posterior atrophic maxilla with short (6-8 mm) implants versus sinus lift with standard length implants: a retrospective study with a three-years follow-up.

Background: sebbene la letteratura recente abbia suggerito che l’utilizzo degli impianti corti possa rappresentare una alternative preferibile alle procedure di rigenerazione ossea nelle aree posteriori atrofiche, perché è un trattamento più semplice e con meno complicazioni, esistono solo pochi studi a medio e lungo termine che abbiano comparato queste tecniche. Scopo: lo scopo di questo studio retrospettivo è quello di valutare se gli impianti corti (6-8 mm) (gruppo impianti corti) possano presentare percentuali di sopravvivenza e valori di riassorbimento osseo marginali simili a impianti di dimensioni standard (≥11 mm) inseriti contemporaneamente ad una grande rialzo di seno mascellare. Materiali e Metodi: in totale, 101 pazienti sono stati inclusi: 48 nel gruppo impianti corti e 53 nel gruppo seno. In ciascun paziente da 1 a 3 impianti sono stati inseriti e tenuti sommersi per 4-6 mesi. I parametri clinici e radiografici valutati sono: i fallimenti implantari, le complicazioni, lo stato dei tessuti molli, e il riassorbimento osseo marginale. Tutti i pazienti sono stati seguiti per almeno 3 anni dal posizionamento implantare. Risultati: il periodo di osservazione medio è stato di 43.47 ± 6.1 mesi per il gruppo impianti corti e 47.03 ± 7.46 mesi per il gruppo seno. Due su 101 impianti corti e 6 su 108 impianti standard sono falliti. Al follow-up finale, si è riscontrato un riassorbimento osseo medio di 0.47 ± 0.48 mm nel gruppo impianti corti versus 0.64 ± 0.58 mm nel gruppo seno. Non sono presenti differenze statisticamente significative fra i gruppi in termini di fallimenti implantari, complicazioni protesiche, tessuti molli, e riassorbimento osseo. Il gruppo seno ha presentato, invece, un maggior numero di complicazioni chirurgiche. Conclusioni: entrambe le tecniche hanno dimostrato un simile tasso di successo clinico e radiografico, ma gli impianti corti hanno ridotto il numero di complicazioni chirurgiche.Background: Although the recent literature suggested that short implants may be a preferable alternative to various bone augmentation procedures in posterior atrophic areas because the treatment is simpler, and associated with less morbidity, limited data have yet been published comparing these two treatment approaches with an observation period longer than 1 year. Purpose: The aim of this retrospective cohort study was to evaluate whether short implants (6 and 8-mm-long) (short group) could be a suitable alternative to standard-length implants (≥11 mm) placed simultaneously with a sinus augmentation (sinus group) for the treatment of atrophic posterior maxillae. Materials and Methods: In total, 101 partially dentate patients were enrolled in the study: 48 in the short group and 53 in the sinus group. One to three implants were placed in each patient and submerged for 4-6 months. Outcome measures were implant failures, complications, soft tissue parameters, and marginal bone levels. Patients were followed for an observation period of at least 3 years from implant placement. Results: The mean observation period was 43.47 ± 6.1 months for short group and 47.03 ± 7.46 months for sinus group. Two of 101 short implants and six of 108 test implants failed. At final follow-up, mean marginal bone loss was 0.47 ± 0.48 mm in the short group versus 0.64 ± 0.58 mm in the sinus group. No significant difference was observed between groups at patient level in terms of implant failures, prosthetic complications, soft-tissue parameters, or marginal bone loss. However, the sinus procedure led to more surgical complications compared with the short implant procedure. Conclusions: Both techniques showed similar clinical and radiographic outcomes, but the short implants provided advantages in terms of reduced number of surgical complications

Narrazione e psicoanalisi. Quale modello di narrazione?

The essay sheds light on the centrality of fiction and narration in the pattern of psychoanalytic relationship. The passage from a medically centered clinical relation to a critical psychotherapy entails a renunciation to any presumption of a universal subjectivity. The subject of such analysis is given just by the construction of a resurgent existential texture in which the fiction and narration  activity plays a prominent role