86,761 research outputs found
Parco Tione. Via Calatafimi, Villafranca di Verona, 2006-2009
No full textProgetto realizzato Parco Tione. Via Calatafimi, Villafranca di Verona, 2006-2009. Autori progetto: A. Aymonino; F. Aymonino; M. Cimato; A. De Fazi; F. Trinca; M. Doimo; G. Smali
Análise de tamanho de trinca e sua propagação através da mecânica da fratura
No full textMonografiaThe following work carried out a theoretical study on the mechanics of the fracture to analyze the critical crack size that can have a certain material. After analyzing the critical crack size the work analyzed how such a defect propagated until it reaches the permissible size. In this work three different types of materials (SAE 1020, 1045 and 4340 steel) were analyzed in three different situations, one in which there is a central crack in the material, in the other there is a lateral crack and finally two lateral crackings. The work will verify how a certain axis of automotive transmission behaves.O seguinte trabalho realizou um estudo teórico sobre a mecânica da fratura para analisar qual o tamanho de trinca crítico que pode ter um determinado material. Após a análise do tamanho de trinca crítico o trabalho analisou como tal defeito se propagou até que chegue no tamanho admissível. Nesse trabalho foram analisados três diferentes tipos de materiais (aço SAE 1020, 1045 e 4340) em três diferentes situações, sendo elas uma em que há uma trinca central no material, na outra existe uma trinca lateral e por fim duas trincas laterais. O trabalho irá verificar como se comporta um determinado eixo de transmissão automotivo.Trabalho não financiado por agência de fomento, ou autofinanciad
Scheda di acquisizione multi piattaforma per misurazioni certificate di power quality
No full textNell'ambito della conservazione dei beni culturali l'accumulo di polveri costituisce un grave problema. Le sue interazioni con i manufatti sono molteplici e i danni che essa può provocare sono notevoli
SISTEMA STRUTTURALE POLIVALENTE PER COPERTURE CON GEOMETRIA AD ACCRESCIMENTO
No full textSISTEMA STRUTTURALE POLIVALENTE PER COPERTURE CON GEOMETRIA AD ACCRESCIMENT
OGGETTO POLIVALENTE CON STRUTTURA AD ACCRESCIMENTO
No full textTrattasi di un sistema strutturale con orditura ad accrescimento spaziale delle membrature,
in grado di definire diverse taglie dello stesso, tutte caratterizzate da unico pilastro composito
centrale, formato dall'unione di sei elementi mistilinei e da un impalcato pressoché orizzontale.
La geometria stellare di sviluppo della struttura ha accrescimento omnidirezionale e modulare
secondo un impianto esagonale, conclusa in sommità da una sagoma quadrata
Metodologia para previsão de propagação de trincas aplicada a um navio tanque
No full textTCC (graduação) - Universidade Federal de Santa Catarina. Campus Joinville. Engenharia Naval.Este trabalho apresenta uma proposta de metodologia baseada nos conceitos da mecânica da fratura linear elástica, a qual prevê a propagação de trincas sob a ação de fadiga em materiais dúcteis, como o aço ASTM A36 utilizado no casco de navios. A metodologia apresentada é resultado de um levantamento bibliográfico das teorias de mecânica geral para que seja aplicado à área naval. A sequência matemática resultante é baseada nas teorias de energia associadas à uma trinca pré-existente sugerida por Griffith (1921) aplicada à Lei de Paris (1961) que relaciona a taxa de propagação do tamanho da trinca decorrente da variação de tensão com o número de ciclos até chegar a um determinado tamanho crítico. É aplicado na tensão do navio um fator de correção devido ao encruamento decorrente no material que torna a região plástica. Além da possibilidade da previsão da vida residual em fadiga para componentes que contenham defeitos já no estágio de propagação, também há a possibilidade de estimar a amplitude máxima da tensão aplicada para que o componente apresente uma durabilidade mínima desejada em fadiga. Para a demonstração da aplicação da metodologia proposta na área naval utilizou-se como modelo um navio de carga. As sociedades classificadoras disponibilizam equações empíricas baseadas em convenções e normas para o cálculo dos momentos de flexão que as ondas geram nos navios, e desta forma pode-se prever as tensões às quais o navio estará submetido quando em navegação. Em suma, com o desenvolvimento deste trabalho, espera-se contribuir com um modelo matemático que permita prever o desempenho de trincas sob a ação de fadiga
A Multi-Platform Data Acquisition Device for Power Quality Metrological Certification
No full textA Data Acquisition USB Device has been realized to
be used in Power Quality monitoring activities. The adopted
solution allows to perform 8 channel simultaneous data
acquisition with external certified time and voltage references,
working at 499 samples per 50 Hz period. The self-powered USB
interface combined to multiplatform FTDI Virtual ComPort
drivers yields a simple-to-use and scalable device; it can be driven
simply sending and receiving data over High Speed RS232 virtual
interfaces, without requiring any advanced programming skill.
The virtual serial communication makes data acquisition software
portable over many platforms, regardless development
environment and programming language. The proposed device
has been tested with custom software written in C# and VB6, than
in LabView and MatLab environment
Variation in cuticular hydrocarbon signatures, hormonal correlates and establishment of reproductive dominance in a polistine wasp
No full textIn many social insects the relationship between reproductive dominance and physiological correlates is poorly understood.
Recent evidence now strongly suggests that cuticular hydrocarbons are important in reproductive differentiation in these societies
where they are used as signals of ovarian activity in reproductive females. In this study we investigated the relationship between
reproductive dominance, size of the corpora allata (CA, producer of Juvenile Hormone, JH) and the proportions of cuticular
hydrocarbons present on the cuticle in overwintering foundresses and both associative (polygynous) and solitary (monogynous)
pre-emergence colonies of the social wasp Polistes dominulus. Size of the CA was positively correlated with ovarian development
in polygynous colonies. In contrast, solitary foundresses possessed significantly smaller CAs than dominant foundresses from
polygynous nests, yet ovarian activity was similar for both female types. CA size variation was associated with variation in
cuticular hydrocarbon proportions. Overwintering, solitary, dominant and subordinate (from associative nests) females all possessed
distinctive cuticular chemical profiles revealed by multivariate discriminant analyses. Our data indicate that the social
environment strongly affects reproductive physiology in this wasp, and we discuss the role of cuticular hydrocarbons in reproductive
signaling in P. dominulus and other social insects
Sleeve Technique Combined With Aortic Valve Replacement: A Simpler Alternative to the Bentall Procedure
No full textAortic root disease can be treated with different surgical techniques. The surgical approach of choice depends on patients’ comorbidities and aortic valve conditions. We describe an operation combining a Sleeve aortic rootplasty with an aortic valve replacement, as an alternative to the classical Bentall procedure. The patient, a 63-year-old man, was admitted to our institution in April 2019 with severe aortic regurgitation, left ventricle dysfunction (ejection fraction = 44%), and aortic root ectasia (476 mm). Since a sparing aortic valve procedure was judged not feasible because of the thickness and retraction of the leaflets, we decided to perform a procedure through a sleeve operation to treat the aortic ectasia and a standard bioprosthetic aortic valve replacement to treat the aortic regurgitation. The patient had an uneventful postoperative course and was discharged on the sixth postoperative day with aspirin as sole antiplatelet treatment. This procedure may be considered an alternative to the Bentall operation. In fact, it may also offer complete treatment for the aortic root disease, avoiding coronary complications due to coronary ostia manipulation and reimplantation
Leaflet kinematics after the Yacoub and Florida-sleeve operations: Results of an in vitro study
No full textOBJECTIVES: The Florida-sleeve is a valve-sparing technique that causes minimal interference to leaflet kinematics and aortic root dynamism. The aim of this in vitro study was to evaluate the effects of the Florida-sleeve and Yacoub techniques on aortic leaflet kinematics. METHODS: Two groups of 6 whole porcine hearts were treated with either the Florida-sleeve technique or the Yacoub technique and tested in a pulsatile loop. Valve fluid dynamics, coronary flow analysis and valve echocardiograms were performed both before and after the procedures. RESULTS: Both procedures showed no difference in rapid valve opening time as compared with their respective baseline values. The Florida-sleeve procedure showed a shorter slow closing time (192 ± 19 ms vs baseline 244 ± 14 ms, P = 0.016) and increased slow closing velocity (-1.5 ± 0.4 cm/s vs baseline -0.8 ± 0.4 cm/s, P = 0.038). In the rapid valve closing phase, the Yacoub procedure showed a trend towards slower closing valve velocity (-16 ± 9 cm/s vs baseline -25 ± 9 cm/s, P = 0.07). The Yacoub procedure showed larger leaflet displacement at the end of the slow valve closing time that was 2.0 ± 0.5 cm vs baseline 1.5 ± 0.3 cm, P = 0.044. When comparing the Florida-sleeve and Yacoub procedures, the former showed statistically significant shorter slow valve closing time (P = 0.017). CONCLUSIONS: This study showed that the Florida-sleeve technique alters the slow closing phase of the aortic valve leaflet kinematics when compared with both the normal baseline and Yacoub procedure, while the latter showed a larger leaflet displacement before the rapid closing valve phase
- …
