329 research outputs found
Transformative social innovation in developing and emerging ecosystems: a configurational examination
Despite the literature on social innovation (SI) in ecosystems growing considerably in recent years, what makes an ecosystem a facilitator for transformative SI remains unexamined, particularly indeveloping and emerging countries. Our research aims to fill this literature gap by determining which combination of characteristics-stemming from stakeholder theory and knowledge management-turns local smallholder coffee farmers in developing and emerging producing countries into autonomous and empowered partners and catalysts for spreading SI initiatives locally. We adopt a configurational approach using fuzzy-set qualitative comparative analysis of 18 SI projects that coffee MNEs, nongovernmental organizations, and institutions have undertaken to favor such an egalitarian value co-creation with local stakeholders. We demonstrate that stakeholder empowerment, cooperative strategic posturing, knowledge transfer, and local knowledge exchange are necessary conditions within the ecosystem to create local autonomy as an antecedent for transformative SI. The novelty in our approach lies in proposing a shift from a pure firm-centric perspective based on stakeholder dependence to a more participatory relational perspective that entails lower-power stakeholders' interdependence and collaboration for autonomous decision-making, thereby advancing fresh thinking on stakeholder and knowledge management applied to SI in developing and emerging contexts. We also propose practical suggestions to deal with stakeholder power's imbalances, which might limit the ecosystems' adaptation toward transformative SI
New Insights on the Photochromism of 2-(2‘,4‘-Dinitrobenzyl)pyridine
The photochromic behavior of 2-(2‘,4‘-dinitrobenzyl)pyridine (α-DNBP) has been followed in poly(methyl methacrylate) (PMMA) films and benzene solutions to clarify the behavior of a precursor state, previously identified in studies on crystalline α-DNBP at low temperatures. In PMMA films, photolysis at temperatures ≤50 K led to the concurrent formation of a NH tautomer and a colorless intermediate, which was stable for several hours. On irradiation at low temperatures and warming the sample, the colorless intermediate was seen to react to produce the NH tautomer in a higher yield than that found in the direct photolysis. Further information on this intermediate has come from flash photolysis studies in benzene solution, in which a new transient absorption has been observed at 335 nm and assigned to this species. This decays within a few microseconds at room temperature to form an OH tautomer, which then interconverts to the NH tautomer. The precursor state is not quenched by oxygen or naphthalene. From consideration of the kinetic and spectral data, it is suggested that this new species corresponds to a nonrelaxed tautomeric form of the OH state of α-DNBP
Buckling of built-up columns of pultruded fiber-reinforced polymer C-sections
This paper presents the test results of an experimental investigation to evaluate the buckling behavior of built-up columns of pultruded profiles, subjected to axial compression. Specimens are assembled by using four (off the shelf) channel shaped profiles of E-glass fiber-reinforced polymer (FRP), having similar detailing to strut members in a large FRP structure that was executed in 2009 to start the restoration of the Santa Maria Paganica church in L’Aquila, Italy. This church had partially collapsed walls and no roof after the April 6, 2009, earthquake of 6.3 magnitude. A total of six columns are characterized with two different configurations for the bolted connections joining the channel sections into a built-up strut. Test results are discussed and a comparison is made with closed-form equation predictions for flexural buckling resistance, with buckling resistance values established from both eigenvalue and geometric nonlinear finite element analyses. Results show that there is a significant role played by the end loading condition, the composite action, and imperfections. Simple closed-form equations overestimate the flexural buckling strength, whereas the resistance provided by the nonlinear analysis provides a reasonably reliable numerical approach to establishing the actual buckling behavior
Dramatic mitigation of capacity decay and volume variation in vanadium redox flow batteries through modified preparation of electrolytes
Electrolyte imbalance caused by the undesired vanadium-ions cross-over and water transport through the membrane is one of the main critical issues of vanadium redox flow batteries, leading to battery capacity loss and electrolytes volume variation. In this work, the evolution of discharged capacity and electrolyte volume variation were firstly investigated adopting commercial electrolyte for hundreds of charge-discharge cycles in vanadium redox flow batteries employing different membranes, varying thickness and equivalent weight. Subsequently, with the support of a 1D physics-based model, the origin of the main phenomena regulating capacity decay and volume variation has been identified and different modifications in the preparation of electrolytes have been proposed. Electrolytes characterized by an equal proton concentration between the two tanks at the beginning of cycling operation turned out to limit capacity decay, while increasing electrolyte proton concentration was effective also in the mitigation of volume variation. The most promising electrolyte preparation combined the effect of high proton concentration and null osmotic pressure gradient between the two tanks: compared to commercial electrolyte this preparation reduced the capacity decay from 47.7% to 20.9%, increased the coulombic efficiency from 96.2% to 98.9% and the energy one from 79.9% to 83.4%, and also implied a negligible volume variation during cycles. The effectiveness of this electrolyte preparation has been verified with different membranes, increasing the range of validity of the results, that could be thus applied in a real system regardless of the adopted membrane
Experimental evaluation of pulse electric current effect on residual stresses in composite-to-copper joint
Surface machining of Ti6Al4V by means of Micro-Electrical Discharging to improve adhesive joining
The Micro-Electrical Discharge Machining (Micro-EDM) technique has been employed to machine micro-patterns with shaped micro-slots on Ti6Al4V surfaces. Ti6Al4V substrates, with and without micro-slots, were bonded using a commercial epoxy adhesive. Optical microscopy and SEM were used to observe the micro-patterned Ti6Al4V surfaces before and after joining and to analyse the fracture surfaces after mechanical tests. The joints were mechanically characterised, with and without micro-patterns, by means of Single Lap Offset (SLO) shear tests under compression to understand the effect of differently shaped micro-slots. The effects of the shape of the micro-slots, their interlocking or overlapping, and their orientation, with respect to the applied load, are presented and discussed in terms of mechanical performance of the joints
Neutron diffraction measurement of residual stresses in CFC/Cu/CuCrZr joints for nuclearfusion technology
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