1,721,776 research outputs found
Development and validation of a novel testing procedure for the evaluation of rutting susceptibility of bituminous binders
No full textThe research reported herein deals with evaluation of rutting susceptibility of different asphalt binders thorough various parameters and correlating them with parameters resulted from tests carried out on their corresponding mixtures. Several factors influence the occurrence of rutting in asphalt mixtures including aggregate properties, composition (aggregate gradation and binder content), and volumetric. However Asphalt binders play a major role in affecting rutting resistance of asphalt mixtures used in road pavements. In the first phase of research four different types of asphalt binders were analyzed by subjecting them to a new protocol combining Single Creep-Recovery (SCR) tests with Multiple Stress Creep (MSC) tests on DSR. Low shear viscosity (LSV) and Multiple Stress Creep Recovery (MSCR) tests were also performed for comparison purposes. LSV and MSCR tests are currently known as standard procedure for the evaluation of rutting susceptibility of binders. However, recent studies have shown the existence of significant drawbacks for LSV and MSCR method when applied to highly modified polymers products. Three shear stress levels (20, 100 and 500 kPa) were applied in case of MSC tests. In case of SCR test 100 kPa shear stress was applied. Two neat binders having same penetration grade 50/70 but different sources were tested at four temperatures (46°C, 52°C, 58°C and 64°C). Asphalt rubber and SBS modified binder were tested at 58°C, 64°C, 70°C and 76°C. The higher range of temperature was used because the aim of testing protocol was to reach steady state flow during creep phase at all temperatures. In case of MSCR tests on AR and PMB tests were started at 64 °C and for NA and NB same temperature range selected for SCR and MSC was also applied. In case of SCR-MSC creep compliance rate from creep phase and permanent compliance from recovery phase were calculated in order to rank binders for their rutting susceptibility. In case of LSV and MSCR tests EVT (Equi-viscous temperature) and non-recoverable compliances were calculated respectively. Single creep-recovery tests combined with multiple stress creep were found to be more accurate in ranking binders for their rutting susceptibility. In the 2nd phase of research the rutting resistance of asphalt mixtures containing above mentioned binders was evaluated. In particular three dense -graded and three gap-graded rubberized mixtures were investigated. Two rubberized gap graded mixtures were prepared in laboratory, one with 2 % filler and the second one with 5 % filler. The third gap graded rubberized mixture was supplied by a plant located in the center of Italy. Amount of binders in all gap graded asphalt mixture was 8 %. The first Dense-graded asphalt mixture was prepared in laboratory with neat binder NA. The second one was collected from local plant which employed neat binder NB, having same penetration grade as the first one but different source and slightly lower maximum design temperature. The third mixture was also prepared in laboratory with SBS polymer modified binder. The binder contents in dense graded asphalt mixtures were 5.5 %. All the three mixtures were analyzed by subjecting cylindrical specimen to Flow number tests on APMT. Flow number has been recognized as newly anti-rutting indicator of asphalt mixtures. Flow numbers for all the mixtures were measured at 3 different temperatures (46°C, 52°C and 58°C). These testing temperatures were selected keeping in mind diversity of pavement temperature across the country. The 2nd purpose of selecting different testing temperature was to study how Flow number varies with change in temperature. The results obtained from mixtures were compared with those obtained from binders. Considering three binders NA, NB and SBS and their corresponding mixtures, it was observed that strong correlation exists between binder parameters and Flow number, so parameters from binder testing can be used to predict rutting susceptibility of their corresponding mixtures. Rectangular specimens were prepared from all rubberized gap graded asphalt mixtures and one traditional mixture. These specimens were tested on wheel tracking test device in order to compare results from AMPT with WT
Physics of Phase Transition Switches
No full textThe semiconductor industry is undergoing an epochal shift, driven by the move to pseudo-three- (2.5D) and three-dimensional (3D) packaging of integrated circuits based on non-scalable classical Boltzmann transistors. In this regard, the scaling potential of post-Boltzmann phase-transition logic switches, memory elements, super-Nernstian sensors, and zero-energy displays remains underappreciated. Broadly defined, phase-transition switches operate between two stable states separated by an energy or power barrier, offering promising solutions for the future of electronics. This tutorial paper provides a foundational and intuitive understanding of the emerging field of phase-transition electronics. It also highlights open issues and research opportunities, serving as a roadmap for advancing this critical technology
A privacy risk assessment for the Internet of Things in healthcare
No full textEl Khodr, M ORCiD: 0000-0001-9904-7551The Internet of Things (IoT) brings connectivity to about every object found in the physical space. It extends connectivity not only to mobile and wearable devices but also to everyday objects. From connected fridges and cars to fully interconnected smart cities, the IoT creates opportunities in numerous domains. This paper briefly highlights the promising applications of IoT in healthcare. The privacy challenges, risks, and vulnerabilities posed by the diversity and heterogeneity of communications in the IoT are then identified, followed by a privacy risk assessment
A novel procedure for the evaluation of anti-rutting potential of asphalt binders
Get PDFAsphalt binders play an important role in the rutting performance of road pavements, and therefore their characterisation is crucial in preventing this type of distress. Several studies have been carried out to replace the G*/sin δ Superpave criteria which were found to be inadequate to capture the anti-rutting potential of these materials. In this paper, a novel testing procedure combining single creep-recovery and multiple stress creep (MSC) tests is proposed. Five asphalt binders of different type and origin were considered. For comparison purposes, two available standard methods, based on low shear viscosity and MSC recovery tests, were included in the study. The obtained experimental results indicated the effectiveness of the test method in highlighting fundamental material properties related to rutting, overcoming some of the drawbacks of existing standard protocol
Correlating creep properties of bituminous binders with anti-rutting performance of corresponding mixtures
Get PDFIn the experimental study described in this paper, rutting properties of different bituminous binders and those of corresponding mixtures characterized by common composition and volumetrics were investigated and compared. Single shear creep-recovery (SSCR) tests were carried out on binders for the determination of their creep compliance rate (CCR), whereas bituminous mixtures were evaluated by referring to their Flow Number (FN), derived from repeated compressive loading tests. Analysis of experimental data revealed the existence of a strong correlation between rutting parameter of binders and permanent deformation response of mixtures. This confirmed the potential of the proposed testing procedure of being adopted for the evaluation of rutting properties of bituminous binders and for their consequent perfomance-related ranking
Reliability of HfO2-Based Ferroelectric FETs: A Critical Review of Current and Future Challenges
Get PDFFerroelectric transistors (FeFETs) based on doped
hafnium oxide (HfO2) have received much attention due to
their technological potential in terms of scalability, highspeed,
and low-power operation. Unfortunately, however,
HfO2-FeFETs also suffer from persistent reliability challenges,
specifically affecting retention, endurance, and variability. A
deep understanding of the reliability physics of HfO2-FeFETs is
an essential prerequisite for the successful commercialization
of this promising technology. In this article, we review the
literature about the relevant reliability aspects of HfO2-FeFETs.
We initially focus on the reliability physics of ferroelectric
capacitors, as a prelude to a comprehensive analysis of FeFET
reliability. Then, we interpret key reliability metrics of the FeFET
at the device level (i.e., retention, endurance, and variability)
based on the physical mechanisms previously identified.
Finally, we discuss the implications of device-level reliability
metrics at both the circuit and system levels. Our integrative
approach connects apparently unrelated reliability issues and
suggests mitigation strategies at the device, circuit, or system
level. We conclude this article by proposing a set of research
opportunities to guide future development in this field
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Passive RFID localization in the Internet of Things
No full textEl Khodr, M ORCiD: 0000-0001-9904-7551Smart home researches have emerged in recent years as a popular field of study in pervasive computing to suggest a solution that can be beneficial for impaired individuals and elderly on their daily life basis. Location tracking accuracy is a major research challenge in smart homes that needs much further investigation.
This paper presents a review of the existing techniques and technologies in location based systems in the Internet of things, and it identifies the research gap of localization in smart home settings. The paper proposes a localization framework for smart home healthcare as well as our preliminary implementation of the localization framework
Variations on the Author
Get PDF“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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