1,721,528 research outputs found
Vapor–Liquid Equilibria of Quaternary Systems of Interest for the Supercritical Antisolvent Process
No full textIn the Supercritical Antisolvent process (SAS), the thermodynamic behavior of complex multicomponent systems can influence the particles’ morphology. However, due to the limited thermodynamic data for multicomponent systems, the effect of solutes is often neglected, and the system is considered as pseudo-binary. It has been demonstrated that the presence of a solute can significantly influence the thermodynamic behavior of the system. In particular, when the SAS process is adopted for the production of drug/polymer coprecipitated microparticles, the effect of both the drug and the polymer in the solvent/CO2 mixture should be considered. In this work, the effect of polyvinylpyrrolidone (PVP), used as the carrier, and of the liposoluble vitamins menadione (MEN) and α-tocopherol (TOC), as model drugs, was investigated as a deviation from the fundamental thermodynamic behavior of the DMSO/CO2 binary system. Vapor–liquid equilibria (VLE) were evaluated at 313 K, with a PVP concentration in the organic solution equal to 20 mg/mL. The effect of the presence of PVP, MEN, and TOC on DMSO/CO2 VLE at 313 K was studied; furthermore, the effect of PVP/MEN and PVP/TOC, at a polymer/drug ratio of 5/1 and 3/1, was determined. Moreover, SAS precipitation experiments were performed at the same polymer/drug ratios using a pressure of 90 bar. Thermodynamic studies revealed significant changes in phase behavior for DMSO/CO2/PVP/TOC and DMSO/CO2/PVP/MEN systems compared to the binary DMSO/CO2 system. From the analysis of the effect of the presence of a single compound on the binary system VLE, it was noted that PVP slightly affected the thermodynamic behavior of the system. In contrast, these effects were more evident for the DMSO/CO2/TOC and DMSO/CO2/MEN systems. SAS precipitation experiments produced PVP/MEN and PVP/TOC microparticles, and the obtained morphology was justified considering the quaternary systems VLE
Stiffness Ratio and the Diffusion of Fake News
No full textThis paper emphasizes the role of the stiffness ratio that characterizes differential problems modeling the diffusion of fake news. In particular, we propose the employ of the stiffness ratio in order to understand how fast is the transit of fake news in a given population, providing a numerical evidence supporting our approach, based on real data
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
A Design Method for Seismic Retrofit of RC Buildings Using Dissipative Exoskeletons
No full textAn emerging solution among rapid, low-impact, and reversible retrofit strate-gies is the implementation of external additive structures or exoskeletons. Most current research emphasizes non-dissipative steel exoskeletons, such as diagrids or steel braces, while comprehensive design procedures for dissipa-tive exoskeletons remain underdeveloped. This study introduces a design procedure for the seismic retrofitting of RC buildings using dissipative exo-skeletons. The proposed strategy is initially applied to a real-world school building and subsequently validated through nonlinear time-history analyses with various input ground motions
Dissipative steel exoskeletons for seismic retrofit of RC buildings
No full textThis paper addresses the seismic retrofitting of highly vulnerable reinforced concrete (RC) buildings, with a focus on relevant and strategic structures such as schools, public offices, and cultural institutions. It proposes innovative retrofit solutions using external additive structures, or exoskeletons, designed for rapid, low-impact, and reversible interventions. These exoskeletons can be installed while the building remains operational, removed, replaced if damaged, and integrated with energy-efficient upgrades, reducing the time and cost of separate interventions. The research investigates two retrofit strategies for a school building: parallel exoskeletons with eccentric braced frames (EBFs) and steel slit dampers (SSDs), and orthogonal exoskeletons with concentric braced frames (CBFs) and shape memory alloy dampers (SMADs). A displacement-based design methodology ensures optimal energy dissipation and prevents premature buckling. Nonlinear time-history analyses validate the effectiveness of the retrofits across various earthquake scenarios. Peak inter-story drift ratio (IDR) responses are significantly reduced, remaining below the 2% collapse prevention limit. The parallel exoskeleton achieves IDR values of 0.66% and 0.86% in the X- and Y-directions, while the orthogonal exoskeleton records 0.63% and 1.06%, respectively. Additionally, the self-centering capability of SMA braces minimizes residual inter-story drifts, with permanent drifts as low as 0.0321% in the X-direction and 0.0090% in the Y-direction, ensuring repairability even after severe seismic events. These findings highlight the efficacy of dissipative exoskeletons in enhancing structural resilience while maintaining practicality and cost-efficiency for retrofitting critical infrastructure in earthquake-prone regions
Lateral torsional buckling design of dumbbell-shaped steel strip dampers
No full textThe concept of “structural fuse” for seismic energy dissipation has been widely adopted in both design standards and research worldwide. Among the metallic structural fuses, slit-yielding dampers, which dissipate energy through in-plane yielding of steel strips, have shown significant promise due to their high ductility and stable hysteretic behavior. However, their effectiveness can be compromised under bi-directional deformations, which may trigger lateral-torsional buckling. This study examines how geometric parameters influence the distribution and accumulation of plastic strains, the onset of buckling, and the energy dissipation capacity of dumbbell-shaped steel strip dampers. A refined non-linear finite element model (FEM) was developed, validated against experimental results, and used to perform non-linear buckling analyses considering initial geometric imperfections. A comprehensive parametric study was carried out on dumbbell-shaped steel strips with varying geometries to assess their susceptibility to yielding and lateral-torsional buckling. The findings highlight the importance of precise geometric control in the design of dumbbell-shaped steel strip dampers to ensure stable energy dissipation under cyclic loading. This is due to the high sensitivity of buckling-induced strength degradation to geometric parameters such as the length-to-thickness ratio, slenderness, aspect ratio, and initial imperfection amplitude. For example, at an aspect ratio of 5.5, an 8 % increase in slenderness resulted in a 39 % reduction in strength, while increasing the initial imperfection from L0/1000 to L0/500 led to a 30 % drop in peak strength for slenderness of 105.63. To address this, acceptance criteria based on buckling-induced resistance degradation were defined to determine a critical slenderness threshold. A regression analysis revealed a strong correlation between critical slenderness and initial imperfection, with regression coefficients linearly dependent on the aspect ratio. The model achieved coefficients of determination (R2) ranging from 0.9818 to 0.9969 under monotonic loading, and from 0.8980 to 0.9881 under cyclic loading. Based on this analysis, a practical design formula was developed to predict the critical slenderness of dumbbell-shaped steel strips under cyclic loading. Calibrated using the FEM dataset and validated across a range of imperfections and aspect ratios, the formula demonstrated strong accuracy, with standard deviation from 0.0145 to 0.0452, and standard error varying from 0.0065 to 0.0202
Variations on the Author
Full text link“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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Vapor–Liquid Equilibria of Quaternary Systems of Interest for the Supercritical Antisolvent Process
No full textIn the Supercritical Antisolvent process (SAS), the thermodynamic behavior of complex multicomponent systems can influence the particles’ morphology. However, due to the limited thermodynamic data for multicomponent systems, the effect of solutes is often neglected, and the system is considered as pseudo-binary. It has been demonstrated that the presence of a solute can significantly influence the thermodynamic behavior of the system. In particular, when the SAS process is adopted for the production of drug/polymer coprecipitated microparticles, the effect of both the drug and the polymer in the solvent/CO2 mixture should be considered. In this work, the effect of polyvinylpyrrolidone (PVP), used as the carrier, and of the liposoluble vitamins menadione (MEN) and α-tocopherol (TOC), as model drugs, was investigated as a deviation from the fundamental thermodynamic behavior of the DMSO/CO2 binary system. Vapor–liquid equilibria (VLE) were evaluated at 313 K, with a PVP concentration in the organic solution equal to 20 mg/mL. The effect of the presence of PVP, MEN, and TOC on DMSO/CO2 VLE at 313 K was studied; furthermore, the effect of PVP/MEN and PVP/TOC, at a polymer/drug ratio of 5/1 and 3/1, was determined. Moreover, SAS precipitation experiments were performed at the same polymer/drug ratios using a pressure of 90 bar. Thermodynamic studies revealed significant changes in phase behavior for DMSO/CO2/PVP/TOC and DMSO/CO2/PVP/MEN systems compared to the binary DMSO/CO2 system. From the analysis of the effect of the presence of a single compound on the binary system VLE, it was noted that PVP slightly affected the thermodynamic behavior of the system. In contrast, these effects were more evident for the DMSO/CO2/TOC and DMSO/CO2/MEN systems. SAS precipitation experiments produced PVP/MEN and PVP/TOC microparticles, and the obtained morphology was justified considering the quaternary systems VLE
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