Search results for "force"
showing 10 items of 3423 documents
Interlaminar fracture toughness behavior of electron-beam cured carbon-fiber reinforced epoxy-resin composites
2013
The work describes the preparation and physical-mechanical characterization of unidirectional CFRP panels manufactured by an electron beam curing technique. Delamination fracture toughness in Mode I and II is investigated in order to evaluate the influence of fiber–matrix adhesion strength, matrix toughness and matrix crosslinking density as determined by the radiation curing process. A matrix system comprising a DGEBA epoxy monomer and an initiator of cationic polymerization have been used, with one batch of resin mixed with a PES monomer in order to enhance matrix toughness. Curing was achieved with a pulsed 10 MeV Electron Beam accelerator. Thermally cured composite systems have also bee…
Estimation of interfacial fracture toughness based on progressive edge delamination of a thin transparent coating on a polymer substrate
2010
Evaluation of interfacial toughness of sub-micron-thickness layers deposited on a ductile substrate is a challenging task which has motivated different experimental approaches Fragmentation testing was used in the present study as a means of interface characterization of a silicon-nitride-coated polyimide substrate. During the test, after an initial rapid segmentation-cracking phase, the coating fragments developed edge delaminations which propagated in a stable manner with further increase in the applied strain The debonding process was modelled by the finite element method Incorporating a cohesive zone at the front of the interfacial crack The edge cracks were found to be dominated by mod…
Evaluation of different mechanical fruit harvesting systems and oil quality in very large size olive trees
2014
In 2006 and 2009, trials were carried out in the Apulia region in Southern Italy to evalu-ate the possibility of mechanizing olive harvesting in groves of old and very large trees. The trees belonged to the cultivars ‘Cellina di Nardò’ and ‘Ogliarola Salentina’. They were 60-100 years old and 7-9 m tall with a canopy volume of 140-360 m3. In the first half of November 2006, with a mechanical beater mounted on a tractor plus hand-held pneumatic combs, the harvesting yield was close to 90% of the total olives present in the canopy, and the harvesting working productivity was around 60 kg of harvested olives h-1 worker-1. With a self-propelled shaker attached to the main branches the harvestin…
La libertà sindacale fa irruzione in caserma
2021
Il commento analizza la recente giurisprudenza di merito sulla repressione della condotta antisindacale nell'ordinamento militare, alla luce dei principi costituzionali e dell'ordinamento sovranazionale, e del recente disegno di legge sul sindacato militare. The current work deals with the recent labour court decisions on anti-unions behaviours in the military legal framework, on the grounds of constitutional and international principles, and the recent bill on military unions.
Migrazioni forzate e diritti disattesi. Lo sguardo di genere sui bisogni di frontiera
2021
La definizione di “tratta di esseri umani”, adottata dal Protocollo delle Nazioni Unite, descrive gli elementi che identificano un fenomeno rilevato su scala mondiale che occupa i primissimi posti delle classifiche relative ai crimini internazionali per la diffusione e la numerosità di casi. Esso prevede l’induzione forzata a varie forme di sfruttamento e, fra queste, un posto di rilievo occupa quello relativo allo sfruttamento a scopo prostitutivo. Malgrado accordi europei e leggi nazionali convergano sul piano giuridico, allo stato attuale, la condizione di “vittima di tratta” fatica ad essere riconosciuta come tale da un sistema di protezione e accoglienza che in Europa evidenzia procedu…
Effect of 5% body weight forward pulling on dynamics of treadmill running
2003
Forward pulled running on a treadmill is known to increase mechanical and decrease metabolic constrains relative to normal running. This experimental situation was used to investigate the variations of the mechanical parameters induced by the pulling. Ten subjects ran during 3 min at individually predetermined constant speeds of 16.4 ± 1.4 km · h-1 on a treadmill while being forward pulled by a load equal to 5% of their body weight. Ground reaction forces were recorded during the last 30 s of the run. Kinematic parameters of the stride as well as impulses and mechanical work were then calculated. Stride frequency did not change, while horizontal impulses were highly modified (+38% and -28%,…
Understanding the stereoselectivity in Brønsted acid catalysed Povarov reactions generating cis/trans CF3-substituted tetrahydroquinolines: a DFT stu…
2016
The Bronsted acid (BA) catalysed Povarov reactions of (E)-1-phenyl-N-(4-(trifluoromethyl)phenyl) methanimine with 1-vinylpyrrolidin-2-one (VPO) and with allyltrimethylsilane (ATMS), affording CF3-substituted cis/trans tetrahydroquinoline (THQ) derivatives, have theoretically been studied using the M06-2X functional together with the standard 6-31G(d) basis set. These BA catalysed Povarov reactions are multistep processes initialised by the nucleophilic attack of the non-substituted carbon atom of the nucleophilic ethylene on the imine carbon atom of the super-electrophilic protonated imine, yielding the corresponding cationic intermediate along the endo/exo stereoisomeric approach mode. Upo…
Synthesis of a new family of bi- and polycyclic compounds via Pd-catalyzed amination of 1,7-di(3-bromobenzyl)cyclen
2008
Abstract New bicyclic cryptand type compounds are synthesized by reacting 1,7-di(3-bromobenzyl)cyclen with 1 equiv of linear polyamines under dilute conditions using Pd-catalyzed amination. Bis(cyclen) and tris(cyclen) compounds containing linear polyamine linkers between benzylated cyclens are obtained by a similar procedure using different reaction conditions. Cyclization of these species via intramolecular catalytic diamination led to tri- and tetracyclic polyaza compounds.
Combination of single-molecule magnet behaviour and luminescence properties in a new series of lanthanide complexes with tris(pyrazolyl)borate and ol…
2020
A series of tris(pyrazolyl)borate mono-, di- and trinuclear complexes, [Tp2Ln]nX (Ln = Eu, Tb, Gd, Dy, Xn− = various mono-, bis- and tris(β-diketonates) has been prepared. The Tb3+ and Dy3+ complexes are luminescent single molecular magnets (SMM) and exhibit luminescence quantum efficiencies up to 73% for the Tb3+ and 4.4% for the Dy3+ compounds. Similar Eu3+ complexes display bright emission only at lower temperatures. The Dy3+ and Tb3+ complexes possess SMM behavior in a non-zero dc field at low temperatures, while the polynuclear Dy3+ complexes also show slow magnetic relaxation even in zero dc field up to 8 K. Ueff-values determined from dynamic magnetic measurements were up to 31 and 6…
Darstellung einiger oligomerer Cyclo{oligo[(2-hydroxy-1,3-phenylen)methylen]}e. Spektroskopische Untersuchung ihrer Pseudorotation
1978
Es wird die Darstellung von Cyclo{tris[(2-hydroxy-5-methyl-1,3-phenylen)methylen]-(2-hydroxy-5-tert-butyl-1,3-phenylen)methylen} (4a), Cyclo{bis[(2-hydroxy-5-methyl-1,3-phenylen)methylen]-bis[(2-hydroxy-5-tert-butyl-1,3-phenylen)methylen]}(4b) und Cyclo-{pentakis[(2-hydroxy-5-methyl-1,3-phenylen)methylen]} (4c) beschrieben. Die IR-Spektren zeigen, das die phenolischen Hydroxygruppen der Vierringverbindungen 4a und 4b intramolekulare, vom Losungs(CCl4)- oder Zerteilungsmittel (KBr) weitgehend unabhangige Wasserstoffbrucken bilden, die bei der pentameren Ringverbindung 4c schwacher sind. Anhand der 1H-NMR-Spektren last sich bei diesen Verbindungen eine Pseudorotation nachweisen. Die Massenspe…