Thermomechanical Characterization of Carbon Black Reinforced Rubbers During Rapid Adiabatic Straining

The thermo-mechanical properties of carbon black reinforced natural and styrene butadiene rubbers are investigated under rapid adiabatic conditions. Eleven carbon black grades with varying surface area and structure properties at 40 parts per hundred (phr) loading are studied and the unreinforced equivalents are included for reference. The results show a strong correlation of the modulus, mechanical hysteresis, temperature rise and calculated crystallinity of the rubbers measured in tensile extension with strain amplification factors. This highlights the influence of matrix overstraining on microstructural deformations of the rubber upon extension. The strain amplification factors are calculated via the Guth-Gold equation directly from carbon black type and loading, allowing a correlation of the fundamental morphological properties of carbon black with thermal and mechanical properties of rubbers upon extension. Analysis of the thermal measurements of the rubber compounds upon extension and retraction and contrasting between crystallizing and non-crystallizing rubbers reveals that a substantial irreversible heat generation is present upon extension of the rubber compounds. These irreversible effects most likely originate from microstructural damage mechanisms which have been proposed to account for the Mullins Effect in particle reinforced rubbers.

TRACS JIP – TTR Life Extension Process

The Tensioned Riser Assessment for Continued Service (TRACS) JIP develops a structured life extension process for TTR systems including single casing, dual casing, buoyancy can supported and tensioner supported TTRs. The JIP bridges regulatory and API frameworks and achieves industry consensus on analysis, inspections, and documentation. The life extension process developed in this JIP consists of detailed roadmaps that guide the operator through the different assessment steps starting from initial data gathering through to the development of the forward-looking IMP. The JIP life extension process is based on a threat assessment philosophy which ensures identification and assessment of all possible threats to the integrity of the TTR in its extended life. The JIP process is validated against three real life TTR systems that are nearing the end of their design lives. Potential threats to the integrity of these TTRs during the projected continued service beyond the design life are identified and specific inspection and analysis recommendations to safely manage or mitigate these threats are made. The JIP also provides TTR life extension analysis guidance while considering the opportunities to reduce conservatism compared to new designs. Inspection of TTRs is challenging due to accessibility issues and the pipe in pipe construction. Several subsea NDE inspection tools are surveyed in this JIP and their applicability to TTRs is discussed.

ICARE (Introduction, Connection, Application, Reflection, and Extension): Analysis of Effectiveness in Improving Student's Communication and Collaboration Ability

This study aims to analyze the effectiveness of the Introduction, Conection, Application, Reflection, and Extension (ICARE) learning model in order to improve students' communication and collaboration skills. This research method is quantitative research with a Quasi-Experiment Design approach. Data collection techniques used in this study were observation, tests and documentation. Collecting data in this study is a documentation technique. This method is used to obtain research data in the form of a list of student names, subject syllabus, even semester final exam questions grid, objective questions and even semester final exam answer keys. The ICARE learning model can improve students' communication skills and student collaboration skills. Each stage in the ICARE model leads students to complete knowledge. Complete knowledge with good skills can optimize students' communication and collaboration skills. Seeing the development of the learning model used with its modification and implementation taking place in such a complex and directed manner, the ICERE learning model is considered capable of being a solution that can be used in the learning process primarily to see communication and collaboration skills so that it has bargaining power as a solution in current learning

Accuracy of Thresholds Based on Cadence and Lifestyle Counts per Minute to Detect Outdoor Walking in Older Adults With Mobility Limitations

Objective: To determine the optimal threshold, based on cadence and lifestyle counts per minute, to detect outdoor walking in mobility-limited older adults. Methods: Older adults (N = 25, median age: 77.0 years, interquartile range: 10.5) wore activity monitors during 80 outdoor walks. Walking bouts were identified manually (reference standard) and compared with identification using cadence thresholds (≥30, ≥35, ≥40, ≥45, and ≥50 steps/min) and >760 counts per minute using low frequency extension analysis. Results: Median walking bout duration was 10.5 min (interquartile range 4.8) and median outdoor walking speed was 0.70 m/s (interquartile range 0.20). Cadence thresholds of ≥30, ≥35, and ≥40 steps/min demonstrated high sensitivity (1.0, 95% confidence intervals [0.95, 1.0]) to detect walking bouts; estimates for specificity and positive predictive value were highest for ≥40 steps/min. Conclusion: A cadence threshold of ≥40 steps/min is recommended for detecting sustained outdoor walking in this population.