1,721,014 research outputs found
Load interaction effects in propagation lifetime and inspections of railway axles
Full text linkAs well known, an interaction effect arises, on crack propagation, when a specimen or a component is
subjected to variable amplitude fatigue loading. Depending on the applied load sequence, a certain
amount of retardation or acceleration can then be observed, on the fatigue crack growth rate, with
respect to the constant amplitude case. In the case of structural ductile materials, the interaction phenomenon
is mainly addressed by the local plasticity at the crack tip and can be explained, from a global
point of view, by adopting the crack closure concept. In the present research, load interaction effects in a
medium strength steel for railway axles are experimentally analyzed by companion and full-scale specimens.
The experimental outcomes show a significant retardation with respect to a simple no-interaction
approach and the Strip-Yield model offers good, yet conservative, estimates of crack advance. The consequences
of crack growth retardation on the inspection periodicity of railway axles are then discussed
La rete di rapporti orientati ed interconnessi nel sistema agroalimentare: una proposta di analisi di filiera
No full textThere is an extensive debate concerning the best approach to analyse the relationships into the "chain", and the problem of the information availability which should provide a clear identification of the object of analysis is not yet solved. This is true in particular with regard to the agri-food system.
This study aims to underline that the incompatibility between analytical level of information and the theoretical construct of reference is often problematic for the studies of the agri-food system. Moreover this study highlights that the concept of system borrowed by the General System Theory (von Bertalanffy, 1968) and by Malassis (Malassis, 1973; 1979), is an approach able to design and to analyse the agri-food network.
The representation of the system as a net oriented relationships is a tool capable of recognising the subjects involved into the network and also the functional relationships among them
Fretting fatigue analysis of full-scale railway axles in presence of artificial micro-notches
No full textAxles are one of the most critical components in railway vehicles and fretting fatigue is one of the open problems in this area. The need for a methodology for analyzing crack growth behavior under a fretting fatigue condition is essential, since determining it experimentally is a challenging task. In this case, a series of tests were performed on full-scale axles with artificial micro-notches. A series of three-dimensional finite element simulations was carried out to estimate fretting fatigue crack propagation path and residual lifetime of an existing crack beneath the axle-wheel's press-fit contact. Maximum tangential stress criteria were adopted to evaluate the crack propagation path. A model is proposed, based on the concept of cyclic R-curve and FE simulation results. The model is accurately estimating the fatigue limit of a full-scale axle in presence of artificial micro notches with an error less than 6% in comparison to the full scale experiments
Investigation of fatigue crack growth in full-scale railway axles subjected to service load spectra: Experiments and predictive models
Full text linkIn this paper, a series of experimental investigations was performed on full-scale railway axles to analyze the fatigue crack growth behavior of EA4T steel under load spectrum derived from real operating conditions. The experimental results were compared to life predictions carried out adopting two models: (i) the conventional Nasgro equation and (ii) the cyclic R-curve concept implemented in the Modified Nasgro equation for describing the crack growth behavior of an arbitrary crack length. The results show that the life predictions performed by means of the Modified Nasgro equation coincide well with the experimental results with an underestimation of the residual lifetime less than 32%, while the traditional Nasgro equation leads to significant overestimation (≈120%) of the residual lifetime for load spectra close to the in service scenario
Qualita' e sicurezza nei sistemi agroalimentari: innovazioni tecnologiche, implicazioni organizzative ed economiche
No full textInnovation, quality and marketing manager in the food industry
No full textThe agri-food enterprises are more and more aware of their responsibilities and their social role and they require the development of innovative marketing strategies, based on the principles of sustainabi-lity and characterized by a strong orientation to the society. Starting from the importance of innovation for the sustainable development in socioeconomic and environmental terms, the study analyzes the links between sustainable innovation and food quality focusing on the communication innovations. In this regard, the study provides an overview on the evolution of marketing theory (ethical, social, responsible and sustainable), underlining the need to push also the agri-food system towards a responsible valorization as an innovative form of sustainable communication. Finally, it provides useful insights to policy makers and stakeholders on the tools required to foster and support sustainable development of agri-food sector and to create synergies between public and private interests
Evaluation of the Potential Interest of Italian Retail Distribution Chains for Kamut-Based Products
No full textKamut® is a registered trademark cereal (an organic crop) whose origins are much older; it has Egyptian origins and at the present time it is grown in different areas of the world (mainly in Montana and Canada), but considering the agronomic requirements of this crop, the tests in Thailand are the most reliable. Evaluation of the interest of retail distribution chains for Kamut-based products belongs to the researches regarding the evaluation of the
quality food products trade. In this case, countries involved are Thailand, one of the most important producers, and Italy, one of the most important market of the EU. Qualitative analysis technique was the most appropriate tool. This survey consisted of in-depth semistructured interviews directed at Italian large scale retails (purchasing and marketing managers). The final information were obtained through a subjective analysis of the content of the interviews’ summaries, a statistical analysis of the content of the interviews and the creation of conceptual positioning maps. The awareness of the product, the communicative factor, the consumers’ reactions, the specific requirements of the distribution chains and production areas are some of the most important elements that can influence the creation and the development of a international trade relationship
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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