177,113 research outputs found
Some analytical solutions of functionally graded Kirchhoff plates
No full textThe elastostatic problem of a functionally graded KIRCHHOFF plate, with no kinematic constraints on the boundary, under constant distributions of transverse loads per unit area and of boundary bending couples is investigated. Closed-form expressions are provided for displacements, bending–twisting curvatures and moments of an isotropic plate with elastic stiffness and boundary distributed shear forces, assigned respectively in terms of the stress function and of its normal derivative of a corresponding SAINT-VENANT beam under torsion. The methodology is adopted to solve circular plates with local and ERINGEN-type elas- tic constitutive behaviors, providing thus new benchmarks for computational mechanics. The proposed approach can be used to obtain other exact solutions for plates whose planform coincides with the cross-section of beams for which the PRANDTL stress function is known in an analytical form
Il polline e la ruggine : Memoria, lavoro, deindustrializzazione a sesto San Giovanni (1985-2015)
No full textIl polline e la ruggine. Memoria, lavoro, deindustrializzazione a Sesto San Giovanni (1985-2015)
Film documentario di Riccardo Apuzzo, Roberta Garruccio, Sara Roncaglia e Sara Zanisi
«Le Rust Belt di tutto il mondo non sono mai qualcosa di statico, rappresentano il dramma culturale di comunità in transizione, di persone che faticano a trovare posto al proprio passato nel proprio presente» (Kathryn Marie Dudley, The End of the Line, 1994)
Come può il cinema documentario offrire uno strumento di indagine storica ed etnografica sulla società contemporanea? Come si ripensano i luoghi che sono stati industriali e sono oggi in mezzo a una trasformazione incerta? Come si ripensano e li ripensano le persone che li hanno vissuti e che li vivono? Quale relazione esiste tra passato industriale e memoria di chi ne ha fatto e ne fa esperienza oggi? Come coinvolgere la comunità e restituire i risultati di una ricerca su questi temi?
“Il polline e la ruggine” cerca di rispondere a queste domande. È un film documentario che nasce da un più ampio progetto di ricerca dal titolo “Laboratorio Industria. Trasmettere e narrare le culture del lavoro e le metamorfosi degli spazi attraverso gli archivi delle fabbriche di Sesto San Giovanni” promosso da Fondazione Isec e Dipartimento di scienze della mediazione linguistica e di studi interculturali dell’Università degli studi di Milano e finanziato da Regione Lombardia - Fondo Sociale Europeo: la ricerca, realizzata da Roberta Garruccio, Sara Roncaglia e Sara Zanisi, ha permesso di raccogliere quasi 50 interviste in profondità con imprenditori, sindacalisti, dirigenti e lavoratori delle imprese dismesse. La ricerca ha intrecciato questa documentazione orale, ora conservata presso la Fondazione Isec, con una vasta documentazione di archivio, tra cui fotografie, filmati, mappe, progetti.
“Il polline e la ruggine” vuole contribuire a conservare e fare conoscere le narrazioni e le rappresentazioni di un luogo trasformato dalla deindustrializzazione, Sesto San Giovanni, concentrandosi in particolare sulla dismissione delle acciaierie Falck e sui significati talvolta molto diversi che le persone attribuiscono agli stessi processi.Pollen and Rust. Memory, Work and Deindustrialization in Sesto San Giovanni (1985-2015). Our research has been funded by the Lombardy Region; and we have worked in partnership with a local Foundation (ISEC – Institute for the history of contemporary age), an independent Association for ethnographic research (AVoce). One of the main requirements of the Lombardy Region’s call was the ability to reach out to a wider audience with respect to a strictly academic one. The call put a strong emphasis on dissemination, in order to involve /solicit the interest of the general public and go outside the university rooms. We intended our project as a project of public history and our research resulted in different research products: the documentary “Pollen and Rust” is one of them.
The documentary has no voice-over, not a single narrator; it is the result of a tight editing of almost 50 interviews. We have asked people: How they remember both industrial work and its loss; How they remember the aftermath of the closings; How they use the history of deindustrialization to understand the present and think about the future.
We mainly interviewed former workers: blue and white collars, local trade union leaders, residents. We interviewed mostly male workers, but also women. We interviewed mostly older workers, but also younger ones, in training [for becoming mechanics or chef in a school located in a former Falck building and new creative professionals.
In the documentary, we did not make any attempt to determine whether the steel plants in Sesto should or should not have been closed, instead we tried to elicit the “reasons” people invoked, and the options they faced. Our ultimate aim was to deconstruct the predominant inevitability discourse for closing.
That is why we interviewed middle and top managers as well: in particular, we met some of the Falck technical staff -mostly industrial engineers who spent their career in the firm - and the Falck top HR Executives who arrived at Falck at the beginning of the ‘90s to manage both the layoffs and the social buffers during the plant’s closing. In their experience of job insecurity, middle managers surely had more personal resources to mobilize in respect to workers (more human capital, for instance, and likely more financial resources), but they also have less or no access to social buffers, and stronger expectations about their own career and on upward mobility.
At the same time, in the transition, they experienced a total lack of social visibility. One of the main findings in our research has been that the most visible tension in the sense-making and memory of the abandoning the steelworks is the one between old middle managers and new top managers, especially the HR managers that came to Falck from outside at the beginning of the 1990s, new managers that held key positions knowing little or nothing about steel making and the Falck company.
So far, little or no attention has been paid to this perspective, which is also the middle class perspective vis a vis the broken promises of the upward mobility which was embodied in post war growth, and ist triad (big government /big business and big labour). We believe that this general trend in the big business under the Globalization pressure is quite well exemplified in the Falck case.
Not everyone is scarred by Deindustrialization: Deindustrialization is experienced differently, with winners and losers: at Falck we could explore those kind of fractures. So I believe that the documentary captures at least 4 narratives: the workers, the trade unionists, the insider middle managers, the outsiders top managers. But there is one more narrative: we took interest in considering not only those who are displaced from manufacturing jobs, but also their children; we took also interest in considering how those affected by Deindustrialization remember it, but we also met people who have no direct experience of industrial work: for them Deindustrialization is not based on memories, but rather inscribed in their parents’ narratives or in Sesto’s industrial heritage landscape.
Sesto has experienced Deindustrialization, but not a post-industrial transformation; the city is rather in a slow process of moving from an industrial past towards a still uncertain future
The huge moloch of the second industrial revolution was demolished or emptied, but what is left now? “What has been labeled Deindustrialization in the intense political heat of the late 70s and early 80s turned out to be: a more socially complicated, historically deep, geographically diverse, political perplexing phenomenon than previously thought” [COWIE and HEATHCOTT 2002
Novel local/nonlocal formulation of the stress-driven model through closed form solution for higher vibrations modes
No full textIn the present work, an innovative two-phases local/nonlocal constitutive mixture model based on the stress-driven model for free vibrations problems is presented. The above two-phases model has been formulated by defining a convex combination of local/nonlocal phases through a mixture parameter and the closed form solution for free vibrations problems is given. The proposed local/nonlocal model has been applied to compute the natural frequencies of four nanobeams study cases. The results are presented in terms of normalised natural frequency as function of both nonlocal and mixture parameters. First, the influence of the two parameters is studied. The effectiveness of the present model is discussed by comparing the results with those obtained by applying the Gradient Elasticity theory. Finally, the normalised natural frequencies for the second, third and fourth modes of vibrations are presented and discussed for each study case
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Free vibrations of elastic beams by modified nonlocal strain gradient theory
No full textSize-dependent axial and flexural free vibrations of Bernoulli-Euler nano-beams are investigated by the modified nonlocal strain gradient elasticity model presented in (Barretta & Marotti de Sciarra, 2018). The corresponding elastodynamic problem, with the natural constitutive boundary conditions, is solved by an effective analytical methodology. Axial and flexural fundamental frequencies are determined for cantilever and fully-clamped nano-beams. Effects of nonlocal and gradient scale parameters on fundamental frequencies are examined and compared with those obtained by Eringen's local/nonlocal mixture model. New benchmarks are found for vibrations of beams. The adopted nonlocal strain gradient model, with the appropriate constitutive boundary conditions, is capable of capturing both softening and stiffening dynamical responses. Accordingly, it provides an advantageous approach for design and optimization of a wide range of nano-scaled beam-like components of Nano-Electro-Mechanical-Systems (NEMS). (C) 2018 Elsevier Ltd. All rights reserved
Nonlocal strain gradient exact solutions for functionally graded inflected nano-beams
No full textThe size-dependent bending behavior of nano-beams is investigated by the modified nonlocal strain gradient elasticity theory. According to this model, the bending moment is expressed by integral convolutions of elastic flexural curvature and of its derivative with the special bi-exponential averaging kernel. It has been recently proven that such a relation is equivalent to a differential equation, involving bending moment and flexural curvature fields, equipped with natural higher-order boundary conditions of constitutive type. The associated elastostatic problem of a Bernoulli-Euler functionally graded nanobeam is formulated and solved for simple statical schemes of technical interest. An effective analytical approach is presented and exploited to establish exact expressions of nonlocal strain gradient transverse displacements of doubly damped, cantilever, clamped simply supported and simply supported nano-beams, detecting thus also new benchmarks for numerical analyses. Comparisons with results of literature, corresponding to selected higher-order boundary conditions are provided and discussed. The considered nonlocal strain gradient model can be advantageously adopted to characterize scale phenomena in nano-engineering problems
Axial and torsional free vibrations of elastic nano-beams by stress-driven two-phase elasticity
No full textSize-dependent longitudinal and torsional vibrations of nano-beams are examined by two-phase mixture integral elasticity. A new and efficient elastodynamic model is conceived by convexly combining the local phase with strain- and stress-driven purely nonlocal phases. The proposed stress-driven nonlocal integral mixture leads to well-posed structural problems for any value of the scale parameter. Effectiveness of stress-driven mixture is illustrated by analyzing axial and torsional free vibrations of cantilever and doubly clamped nano-beams. The local/nonlocal integral mixture is conveniently replaced with an equivalent differential law equipped with constitutive boundary conditions. Exact solutions of fundamental natural frequencies associated with strain- and stress-driven mixtures are evaluated and compared with counterpart results obtained by strain gradient elasticity theory. The provided numerical benchmarks can be effectively employed for modelling and design of Nano- Electro-Mechanical-Systems (NEMS)
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Selective photo-oxidation of ethanol to acetaldehyde and acetic acid in water in presence of TiO2 and cupric ions under UV–simulated solar radiation
No full textThe selective oxidation of ethanol to acetaldehyde and acetic acid in aqueous solution, through sacrificial TiO2 photocatalysis in the presence of cupric ions at ambient temperature, under acidic conditions and artificial sunlight, has been investigated. Different commercial TiO2 photocatalyst samples and loads have been tested. The influence of starting cupric ion and ethanol concentrations has been investigated. Ethanol conversion, overall product selectivity, and product yield have been calculated and compared with the aim of maximizing the recovery of valuable commodity chemicals. For the run corresponding to optimal values of ethanol conversion, overall product selectivity and yields, a value of process photoefficiency equal to 33% has been calculated. Based on the experimental results, the main focus of the study has been the development of a photo-oxidation mechanism and a new kinetic model constituted by a set of mass balance equations for the main species involved in the photocatalytic oxidation process. The model has been employed for analyzing data collected at different starting substrates and cupric ion concentrations. A reliable prediction of the concentrations of cupric ions and organic species during selective photo-oxidation runs has been achieved. The modeling investigation has allowed to estimate for the first time the kinetic parameters not available in the literature review, such as the equilibrium adsorption constants and the rate constants for the hole-capture by sacrificial agents. A new alternative strategy to convert ethanol from biorefinery wastewaters into valuable fine chemicals, by using water as solvent, a low-cost catalyst, solar radiation and ambient temperature, has been proposed and kinetically characterized. The model presented can be easily applied to other photocatalytic systems for the oxidation of organic species over metal doped photocatalysts
Axial and torsional free vibrations of elastic nano-beams by stress-driven two-phase elasticity
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