1,721,483 research outputs found
Design and Construction of a Full-Scale Field Implementation of Internally Cured Concrete for Iowa Pavement Systems
Full text linkSurface evaporation is a process that dries concrete pavement and decreases the cement hydration rate. External curing keeps the surface moist and mitigates surface drying by evaporation, thus enhancing surface cement hydration. Internal curing is a comparatively recent method to increase the duration of cement hydration by using internal water reservoirs without changing the water cement ratio in a concrete mixture. This method has been utilized to improve concrete durability and decrease shrinkage in concrete structures. In this study, Lightweight Fine Aggregate (LWFA) has been used in two county roads in Iowa. In the lab, a testing regime including compressive, and tensile strength, modulus of elasticity, surface resistivity, calorimetry, and scanning electron microscopy has been applied to evaluate the effects of using LWFA. In the field, a Decagon 5TE sensor was used to measure the relative permittivity and temperature of the concrete materials after construction. The laboratory and field results showed that using LWFA improved the mechanical and potential durability properties of concrete by extending cement hydration.This preprint is from Daghighi, Amin and Taylor, Peter C. and Ceylan, Halil and Zhang, Yang, Design and Construction of a Full-Scale Field Implementation of Internally Cured Concrete for Iowa Pavement Systems. Available at SSRN: https://ssrn.com/abstract=4076504 or http://dx.doi.org/10.2139/ssrn.4076504
Dynamic Characterization of a Soft Elastomeric Capacitor for Structural Health Monitoring
No full textStructural health monitoring of civil infrastructures is a difficult task, often impeded by the geometrical size of the monitored systems. Recent advances in conducting polymers enabled the fabrication of flexible sensors capable of covering large areas, a possible solution to the monitoring challenge of mesoscale systems. The authors have previously proposed a novel sensor consisting of a soft elastomeric capacitor (SEC) acting as a strain gauge. Arranged in a network configuration, the SECs have the potential to cover very large surfaces. In this paper, understanding of the proposed sensor is furthered by evaluating its performance at vibration-based monitoring of large-scale structures. The dynamic behavior of the SEC is characterized by subjecting the sensor to a frequency sweep, and detecting vibration modes of a full-scale steel beam. Results show that the sensor can be used to detect fundamental modes and dynamic input. Also, a network of SECs is used for output-only modal identification of a full-scale concrete beam, and results are benchmarked against off-the-shelf accelerometers. The SEC network performs well at estimating both natural frequencies and mode shapes. The resolution of the sensor is currently limited by the available electronics to measure small changes in capacitance, which reduces its accuracy with increasing frequencies in both the time and frequency domain
Effects of Implements of Husbandry (Farm Equipment) on Pavement Performance
Full text linkThe effects of farm equipment on the structural behavior of flexible and rigid pavements were investigated in this study. The project quantified the difference in pavement behavior caused by heavy farm equipment as compared to a typical 5-axle, 80 kip semi-truck. This research was conducted on full scale pavement test sections designed and constructed at the Minnesota Road Research facility (MnROAD). The testing was conducted in the spring and fall seasons to capture responses when the pavement is at its weakest state and when agricultural vehicles operate at a higher frequency, respectively. The flexible pavement sections were heavily instrumented with strain gauges and earth pressure cells to measure essential pavement responses under heavy agricultural vehicles, whereas the rigid pavement sections were instrumented with strain gauges and linear variable differential transducers (LVDTs). The full scale testing data collected in this study were used to validate and calibrate analytical models used to predict relative damage to pavements. The developed procedure uses various inputs (including axle weight, tire footprint, pavement structure, material characteristics, and climatic information) to determine the critical pavement responses (strains and deflections). An analysis was performed to determine the damage caused by various types
of vehicles to the roadway when there is a need to move large amounts agricultural product.Minnesota Department of Transportation Research Services SectionLim, Jason; Azary, Andrea; Khazanovich, Lev; Wang, Shiyun; Kim, Sunghwan; Ceylan, Halil; Gopalakrishnan, Kasthurirangan. (2012). Effects of Implements of Husbandry (Farm Equipment) on Pavement Performance. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/122668
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
Relationships between internal training intensity, heart rate variability, sleep duration, and neuromuscular performance in professional soccer players
No full textPurpose. This study examined the relationship between internal training intensity and physiological and performance markers, including heart rate variability, resting heart rate, sleep duration, and countermovement jump performance in professional soccer players during a five-week preseason. Methods. This longitudinal design included 10 professional soccer players (age: 20.8 ± 2.3 years) with the following variables measured weekly: ITI, heart rate variability (HRV), resting heart rate (RHR), sleep duration, and countermovement jump (CMJ) performance. Results. Results showed a significant reduction in ITI (p < 0.001) across the preseason, reflecting effective intensity manage-ment. CMJ performance showed an initial decline before significantly increasing after week 2 (p < 0.001), while no significant changes were observed in RHRmean (p = 0.25) or lnRMSSDmean (p = 0.27). However, lnRMSSDCV decreased by 39.9%, indicating improved autonomic stability. A moderate negative correlation was observed between lnRMSSDmean and lnRMSSDCV (r = –0.54, p < 0.001), suggesting that greater parasympathetic tone is associated with reduced daily HRV fluctuations. ITI showed moderate negative correlations with Sleepmean (r = –0.32, p = 0.045) and CMJ performance (r = –0.43, p = 0.005) and a positive correlation with lnRMSSDCV (r = 0.35, p = 0.03). Conclusions. Higher ITI is associated with reduced CMJ performance, likely due to fatigue, emphasising the need to monitor CMJ for optimising training loads and preventing overtraining. Similarly, its link to shorter sleep duration highlights the importance of tracking sleep for effective recovery management. Additionally, the inverse relationship between lnRMSSDmean and lnRMSSDCV suggests that greater parasympathetic activity stabilises HRV fluctuations, reflecting improved autonomic balance and aiding in training adjustments. This study highlights the importance of integrating HRV, sleep, and CMJ into preseason training programs for professional soccer players. A tailored training approach emphasising reduced ITI and monitoring autonomic stability and recovery effectively improves physiological resilience and neuromuscular performance, ensuring players’ readiness for the competitive season
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
Optimized Joint Spacing for Concrete Overlays with and without Structural Fiber Reinforcement
Full text linkIn thin concrete overlays (10 to 15 cm, 4 to 6 in), field observations have sometimes shown that not all contraction joints activate initially and, in some cases, do not activate until many years after construction. Contraction joints that do not activate may be considered an inefficient design that can lead to unnecessary maintenance efforts, unnecessary costs, and negative impacts on concrete overlay performance. Optimum joint spacing design for concrete overlays may need to be determined based on factors different from those that are currently considered. This study included an analysis for recommended joint spacing using pavement design software, as well as a field review of joint activation in existing concrete overlays using non-destructive testing. Test sections were also constructed in conjunction with new concrete overlay projects to analyze a wider range of variables and study early-age joint activation behavior. The data showed that joint spacing was the most significant factor affecting joint activation in thin concrete overlays. The addition of 2.4 kg/m3 (4 lb/cy) structural synthetic macro-fibers did not affect the rate of initial joint activation compared to overlays without fibers. A design parameter, slab length over the radius of relative stiffness (L/l), was identified to correlate with joint activation rate and timing. Designing joint spacing to achieve L/l between 4 and 7 may provide the desired balance between maximum, timely joint activation and good overlay performance.This is a manuscript of the article Published as King, Dan & Gross, Jerod & Ceylan, Halil & Chen, Yu-An & Taylor, Peter. (2021). Optimized Joint Spacing for Concrete Overlays with and without Structural Fiber Reinforcement. 598-609. doi: http://dx.doi.org/10.33593/s5rfu1su. Posted with Permission. Copyright 2021 The Authors. This manuscript is licensed under the CC BY-SA 4.0 License
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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