scholarly journals Correlations between mechanical and geometrical parameters in aggregates: a tool for quality assessment and control

2013 ◽  
Vol 47 (4) ◽  
pp. 2069 ◽  
Author(s):  
D. Xirouchakis
Keyword(s):  
Abrasion Resistance ◽  
Shape Index ◽  
Test Methods ◽  
Standard Test ◽  
Geometrical Parameters ◽  
Strongly Correlated ◽  
Data Set ◽  
Resistance To Wear ◽  
And Performance ◽  
And Control

Correlations between mechanical and geometrical parameters in aggregates can be used as quality and performance prediction tools. I evaluated the following parameter pairs: dry and wet resistance to wear (MDE & MDS), and resistance to fragmentation (LA); polishing resistance and abrasion (PSV–AAV); and flakiness and shape index (FI–SI). The data set comprises slags, sedimentary, igneous, and metamorphic rocks tested according to EN standard test methods. FI and SI are positively correlated (r = 0.83) and can be well described by the 1:1 line. Wet and dry resistance to wear are strongly correlated (r = 0.98) with MDE ≈ 2·MDS. Dry resistance to fragmentation (LA) and wet resistance to wear (MDE) are well correlated (r = 0.81), and can be described with the equation LA = 4.95×MDE 0,61 (R2 = 0.69). According to the PSV–AAV correlation, aggregates are divided into two groups with contrasting behavior. Limestones and slags (r = −0.49 to −0.69) exhibit high polishing for high abrasion resistance (high PSV–low AAV), whereas sandstones and mafic to intermediate volcanics (r = 0.44 to 0.39) exhibit high polishing for low abrasion resistance (high PSV–high AAV). Peridotites belong to either PSV–AAV group depending on the soft minerals.

Serviceability Assessment of a Printed Finish on T-Shirts

2021 ◽  
Vol 8 (2) ◽  
pp. 48-53
Author(s):  
Reannan Riedy ◽  
Meredith McQuerry
Keyword(s):  
Abrasion Resistance ◽  
Dimensional Change ◽  
Test Methods ◽  
Standard Test ◽  
Performance Expectations ◽  
Agricultural Worker ◽  
Soil Release ◽  
And Performance ◽  
Typical Consumer ◽  
Change Material

To improve the comfort of agricultural workers, a T-shirt with a printed active cooling finish was evaluated to determine if it would meet the wash life durability and performance expectations of such an arduous application. Six shirts with a printed phase change material (PCM) finish and six shirts without (control) were washed 50 times to replicate a typical consumer wash life. Shirts were evaluated for absorbency, dimensional change, colorfastness, crocking, abrasion resistance, soil release, and smoothness retention according to AATCC and ASTM standard test methods. Testing was conducted before laundering and after 1, 5, 10, 20, 30, 35, 40, 45, and 50 consumer laundry (CL) cycles. Absorbency and dimensional change were significantly influenced by the PCM finish. Results demonstrate the appropriateness of adopting such a finish technology for agricultural worker clothing applications.

Monitoring, Diagnostics, and Prognostics for Robot Tool Center Accuracy Degradation

2018 ◽  
Author(s):  
Guixiu Qiao ◽  
Brian A. Weiss
Keyword(s):  
Health Management ◽  
Control Strategies ◽  
Test Methods ◽  
Component Level ◽  
Data Set ◽  
Root Cause ◽  
Robot Systems ◽  
Robot Performance ◽  
And Control ◽  
Constituent Elements

Over time, robots degrade because of age and wear, leading to decreased reliability and increasing potential for faults and failures; this negatively impacts robot availability. Economic factors motivate facilities and factories to improve maintenance operations to monitor robot degradation and detect faults and failures, especially to eliminate unexpected shutdowns. Since robot systems are complex, with sub-systems and components, it is challenging to determine these constituent elements’ specific influence on the overall system performance. The development of monitoring, diagnostic, and prognostic technologies (collectively known as Prognostics and Health Management (PHM)), can aid manufacturers in maintaining the performance of robot systems by providing intelligence to enhance maintenance and control strategies. This paper presents the strategy of integrating top level and component level PHM to detect robot performance degradation (including robot tool center accuracy degradation), supported by the development of a four-layer sensing and analysis structure. The top level PHM can quickly detect robot tool center accuracy degradation through advanced sensing and test methods developed at the National Institute of Standards and Technology (NIST). The component level PHM supports deep data analysis for root cause diagnostics and prognostics. A reference data set is collected and analyzed using the integration of top level PHM and component level PHM to understand the influence of temperature, speed, and payload on robot’s accuracy degradation.

Aggregate Toughness/Abrasion Resistance and Durability/Soundness Tests Related to Asphalt Concrete Performance in Pavements

1998 ◽  
Vol 1638 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Yiping Wu ◽  
Frazier Parker ◽  
Prithvi S. Kandhal
Keyword(s):  
Asphalt Concrete ◽  
Abrasion Resistance ◽  
Laboratory Tests ◽  
Field Performance ◽  
Strong Relationship ◽  
Test Methods ◽  
Review Of Literature ◽  
Aggregate Properties ◽  
And Performance ◽  
Transportation Agencies

Numerous tests have been developed that empirically characterize aggregate without, necessarily, having a strong relationship to the performance of the final products incorporating these aggregates. This seems to be particularly true for aggregate toughness and abrasion resistance and durability and soundness. Toughness/abrasion resistance and durability/soundness tests for characterizing aggregate used in asphalt concrete were identified and evaluated, and those test methods that best correlate with field performance were determined. Based on a review of literature and specifications, laboratory tests for characterizing aggregate toughness/abrasion resistance and durability/soundness were selected. Sixteen aggregate sources with poor to good performance histories were identified for evaluation with the selected suite of tests. Performance histories of pavements containing these aggregates in asphalt concrete layers were established through personal contacts with state transportation agencies and performance evaluation questionnaires. Aggregate properties from laboratory tests were correlated with field performance. The micro-deval and magnesium sulfate soundness tests provide the best correlations with field performance of asphalt concrete and are recommended for characterizing aggregate toughness/abrasion resistance and durability/soundness.

scholarly journals An Experimental Study on Protective Gloves Used in Pakistan.

2020 ◽  
pp. 64-65
Author(s):  
Beena Zehra ◽  
Hafiz Rub Nawaz ◽  
Barkat Ali Solangi ◽  
Uzma Nadeem ◽  
Mohammad Zeeshan
Keyword(s):  
Experimental Study ◽  
Abrasion Resistance ◽  
Experimental Evaluation ◽  
Test Methods ◽  
Standard Test ◽  
Performance Levels ◽  
Puncture Resistance ◽  
Synthetic Leather ◽  
Physical Tests ◽  
Technical Study

This technical study deals with the experimental evaluation of four different safety gloves, used in Pakistan for protection of hands. The samples were prepared and tested according to their standard test methods EN-388. The samples for EN388 were subjected to three physical tests; puncture resistance (N), abrasion resistance (cycles), tear-resistance (N). The results revealed that the performance levels of synthetic leather/ PVC gloves were found higher than other gloves.

The role of copper ions in hydrogen peroxide bleaching: Their origin, removal, and effect on pulp quality

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 37-46 ◽  
Author(s):  
PEDRO E.G. LOUREIRO ◽  
SANDRINE DUARTE ◽  
DMITRY V. EVTUGUIN ◽  
M. GRAÇA V.S. CARVALHO
Keyword(s):  
Hydrogen Peroxide ◽  
Copper Ions ◽  
Peroxide Bleaching ◽  
Metals Removal ◽  
Peroxide Decomposition ◽  
Equipment Corrosion ◽  
And Performance ◽  
And Control ◽  
Main Effects

This study puts particular emphasis on the role of copper ions in the performance of hydrogen peroxide bleaching (P-stage). Owing to their variable levels across the bleaching line due to washing filtrates, bleaching reagents, and equipment corrosion, these ions can play a major role in hydrogen peroxide decomposition and be detrimental to polysaccharide integrity. In this study, a Cu-contaminated D0(EOP)D1 prebleached pulp was subjected to an acidic washing (A-stage) or chelation (Q-stage) before the alkaline P-stage. The objective was to understand the isolated and combined role of copper ions in peroxide bleaching performance. By applying an experimental design, it was possible to identify the main effects of the pretreatment variables on the extent of metals removal and performance of the P-stage. The acid treatment was unsuccessful in terms of complete copper removal, magnesium preservation, and control of hydrogen peroxide consumption in the following P-stage. Increasing reaction temperature and time of the acidic A-stage improved the brightness stability of the D0(EOP)D1AP bleached pulp. The optimum conditions for chelation pretreatment to maximize the brightness gains obtained in the subsequent P-stage with the lowest peroxide consumption were 0.4% diethylenetriaminepentaacetic acid (DTPA), 80ºC, and 4.5 pH.

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