1,354,728 research outputs found
Characterization and analysis of the interlaminar behavior of thermoplastic composites considering fiber bridging and R-curve effects
No full textThermoplastic composites can enable the development of new manufacturing techniques to make the aviation industry more sustainable while at the same time greatly benefit cost-efficient and high-volume production. One of the thermoplastic composite materials that can enable this transition is AS4D/PEKK-FC. In this work, the interlaminar properties of AS4D/PEKK-FC thermoplastic composite are characterized and analyzed by means of Mode I, II and Mixed Mode I/II at 50:50 tests, while considering fiber bridging and R-curve effects. In order to achieve stable crack propagation the test configurations are adjusted to account for the large fracture process zone ahead of the crack tip and an appropriate data reduction method is selected. The experimental data is reduced using an inverse methodology to extract cohesive laws based on only the load–displacement curves. Additionally, the use of this methodology provides new insights into the validity of two different mode II tests and the influence of fiber bridging on the mixed-mode interlaminar behavior. The interlaminar damage mechanisms are investigated by means of scanning electron microscopy. The resulting cohesive laws are implemented in commercial finite element software in tabular form, without the need for user-subroutines. All experimental test configurations are analyzed using a single material card and it is shown that fiber bridging and R-curve effects are well captured
L'altro che ti trasforma. Recensione di: "In viaggio verso Allah: Lettera di un prete a Monsef, giovane combattente islamico" di Claudio Burgio
No full textThis review explores In viaggio verso Allah, a book by Don Claudio Burgio, written as a deeply personal letter to Monsef, a young Moroccan who left Italy to join jihadists in Syria. Blending reflection and analysis, the book explores radicalization, the loss of authority, and religious deculturation. Don Claudio grapples with his own fears and failures as an educator, ultimately finding in Monsef not just a lost protégé but an opportunity for spiritual growth. Through dialogue and faith, he reaffirms that love and forgiveness can transcend fear and that no relationship is ever truly lost
Design of a risk-averse decision making tool for smart distribution network operators under severe uncertainties: An IGDT-inspired augment ε-constraint based multi-objective approach
No full textIn the context of restructured electricity market and smart grid, uncertainties including renewable generation, load demand, and electricity price would significantly affect the technical and financial aspects of smart distribution networks. This paper presents a risk-averse decision making tool to help distribution network operator (DNO) in short-term operational activities. The objective is to optimize hourly sale prices offered to the customers, transactions (purchase/sale) with the wholesale market, commitment of distributed generation, dispatch of energy storage systems, and planning of interruptible loads in a way that a target profit for the risk-averse DNO is guaranteed. A bi-level information gap decision theory (IGDT) inspired problem is developed to hedge the DNO against risk imposed by the information gap between the forecasted and actual uncertain variables. The bi-level problem is recast into its equivalent single level problem driven by Karush-Kuhn-Tucker optimality conditions. Since the uncertain variables compete with each other to maximize their enveloped-bounds, the augmented ε-constraint method is used to solve the proposed IGDT-inspired multi-objective optimization problem. A Monte Carlo simulation based after-the-fact analysis is conducted to verify the robust performance of the operational decisions. The effectiveness and efficiency of the proposed model are evaluated on the 33-bus and the 118-bus modified test networks
Enhancing Seismic Performance of Steel Plate Shear Walls Through Innovative Design and Curved Shape Slots
No full textThis study introduces innovative Steel Plate Shear Walls (SPSWs) with a specific shape as seismic energy dissipative devices for both new and existing structures. These systems incorporate curved shape slots and varying opening ratios, significantly impacting their seismic performance. A comprehensive numerical investigation of the cyclic behavior of these panels is conducted using the Finite Element Method (FEM) with ABAQUS software. The numerical model is validated by means of the comparison with experimental data of previously tested specimens available in the literature. The analyses provide a thorough assessment of the hysteretic behavior of specimens, including key performance metrics, such as maximum load-carrying capacity, initial stiffness, and out-of-plane displacements up to 5% drift. Additionally, eigenvalue analysis is employed to calculate the critical elastic buckling load for each specimen. The study compares the ratio between the yielding force and the elastic buckling force, as well as critical parameters influencing out-of-plane deformations, for each configuration. Finally, the optimal configuration of innovative SPSWs with a specific shape, incorporating curved shape slots, is suggested based on design parameters related to the hysteretic behavior
SEISMIC PERFORMANCE OF STEEL SHEAR PANELS WITH BUTTERFLY-SHAPED LINKS
No full textA novel lateral force resisting system, namely steel shear panels with Butterfly-
Shaped (BS) links is proposed, which is a promising alternative for improving the buckling
stability and seismic behaviour of conventional steel plate shear walls. To illustrate the
advantages of such a device, specimens with different number of butterfly links have been
numerically investigated. To this purpose, a FE model, which has been preliminary calibrated
on conventional shear panels on the basis of recent experimental tests, has been defined. Then,
the influence on the hysteretic performance of some non-dimensional ratios, which
characterize the butterfly link geometry, namely the slenderness ratio and the taper ratio, is
evaluated. In the whole, the results demonstrate that the shear strength, initial stiffness and
dissipation energy are controlled by the number of butterfly shaped links. In addition, due to
buckling phenomena of butterfly shaped links, the energy dissipation of shear panels with BS
links may significantly decrease. For this reason, three different limit states are evaluated and
specimens which have an improved cyclic behaviour in terms of energy dissipated are
suggested
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Hysteretic behavior of steel shear panels with internal rectangular-shaped links
No full textA novel typology of steel shear panel based on a web plate perforated according to Rectangular-Shaped Links (RSL) with internal links is proposed, to act as an energy dissipation element and improving the progressive overstrain behavior of typical shear plates. Preliminary experimental tests were carried out to investigate the behavior of the proposed system and to determine the influence of the main design parameters on the hysteretic response of tested specimens. The obtained outcomes evidenced that the shear strength, the stiffness and energy dissipation capacity of proposed shear panels are consistently influenced by overstrain in bending around the rectangular-shaped links, due to the slenderness of internal links. In particular, two different buckling modes were identified, namely global shear buckling of the plate, which is partially dissipative, and lateral-torsion buckling of individual rectangular-shaped links and internal links, which may result fully dissipative. Then, a FEM model has been implemented and validated according to the experimental results. Therefore, a parametric analysis has been carried out, considering the main parameters affecting the cyclic response of the specimen. The obtained outcomes allowed to conclude that the polar moment of inertia of links could be used together with the plate thickness to control the hysteretic performance of RSL specimens. In particular, the increasing of the width of internal links could allow the activation of global buckling of the plate, which generally causes significant pinching of hysteretic cycles. Based on the conducted parametric analyses, optimum web plate slenderness ratio and polar moment of inertia of links have been identified, providing useful suggestions for design of the proposed shear panel typology. In addition, an equation to predict the yielding shear strength of these kinds of shear panels has been suggested
Robust day-ahead scheduling of smart distribution networks considering demand response programs
No full textIncreasing penetration of variable loads and renewable resources in smart distribution networks brings about great challenges to the conventional scheduling and operation due to the uncertain nature. This paper presents a novel uncertainty handling framework, based on the underlying idea of robust optimization approach, to portray the uncertainties of load demands and wind power productions over uncertainty sets. Accordingly, a tractable min–max–min cost model is proposed to find a robust optimal day-ahead scheduling of smart distribution network immunizing against the worst-case realization of uncertain variables. In addition, considering demand response programs as one of the important resources in the smart distribution network, participation of customers in both energy and reserve scheduling is explicitly formulated. As the proposed min–max–min cost model cannot be solved directly by commercial optimization packages, a decomposition algorithm is presented based on dual cutting planes to decouple the problem into a master problem and a sub-problem. The master problem finds the day-ahead scheduling, while the sub-problem determines the worst-case realization of uncertain variables within uncertainty sets. Computational results for the modified version of IEEE 33-bus distribution test network demonstrate the effectiveness and efficiency of the proposed model
Incorporating price-responsive customers in day-ahead scheduling of smart distribution networks
No full textDemand response and real-time pricing of electricity are key factors in a smart grid as they can increase economic efficiency and technical performances of power grids. This paper focuses on incorporating price-responsive customers in day-ahead scheduling of smart distribution networks under a dynamic pricing environment. A novel method is proposed and formulated as a tractable mixed integer linear programming optimization problem whose objective is to find hourly sale prices offered to customers, transactions (purchase/sale) with the wholesale market, commitment of distribution generation units, dispatch of battery energy storage systems and planning of interruptible loads in a way that the profit of the distribution network operator is maximized while customers' benefit is guaranteed. To hedge distribution network operator against financial risk arising from uncertainty of wholesale market prices, a risk management model based on a bi-level information-gap decision theory is proposed. The proposed bi-level problem is solved by recasting it into its equivalent single-level robust optimization problem using Karush-Kuhn-Tucker optimality conditions. Performance of the proposed model is verified by applying it to a modified version of the IEEE 33-bus distribution test network. Numerical results demonstrate the effectiveness and efficiency of the proposed method
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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