Correlation between Spatial Fractal and Temporal Chaos During the Sliding Wear Process of AISI 5120 Steel

Abstract The purpose of this paper is to establish the relationship between surface morphology and friction coefficient in the wear process. Different wear stage tests of AISI 52100 ring sliding against AISI 5120 disc were designed and conducted on a rotating setup. The fractal and chaos theories were employed to study the nonlinear features of surface structure and friction signal from spatial and temporal scales. The results showed that 3D surface morphology has fractal nature. The fractal dimension Ds first increased and then stabilized at a maximum and finally decreases dramatically. The multifractal spectrum width Δα presented an contrary evolution trend. The friction coefficient signal has chaotic nature. The standard deviation of distance matrix STD obeyed the evolution rule of a bathtub curve. The correlation value between Ds and STD was − 0.7727, and the correlation value between Δα and STD was 0.7130. The strong correlation between spatial and temporal scales is beneficial to on-line recognition and prediction of wear states in real time.

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Characteristic Parameters and Evolution of the Running-in Attractor

International Journal of Bifurcation and Chaos ◽

10.1142/s0218127419500445 ◽

2019 ◽

Vol 29 (04) ◽

pp. 1950044 ◽

Cited By ~ 2

Author(s):

Cong Ding ◽

Hua Zhu ◽

Guodong Sun ◽

Yu Jiang ◽

Chunling Wei

Keyword(s):

Standard Deviation ◽

Friction Coefficient ◽

Chaotic Attractor ◽

Distance Matrix ◽

Nonlinear Friction ◽

Dynamic Features ◽

Characteristic Parameters ◽

Wear Process ◽

System A ◽

Variation Tendency

The running-in attractor is a chaotic attractor with stability, which forms in the running-in process. Its “formation-stabilization-disappearance” stage can reflect the dynamic features of the nonlinear friction system. To reveal the dynamic features and evolution of the running-in attractor, in this work, wear experiments are implemented on a ring-on-disk tribometer. The friction coefficient signals are then extracted and reconstructed. Based on the reconstructed matrix of the friction coefficient signals, the convergence (CON) and standard deviation of the distance matrix (STD) are proposed. Results show that CON evolves from an increase to the stabilization and then to a decrease. STD presents an inverse variation tendency, evolving from a decrease to the stabilization and then to an increase. A larger CON indicates higher convergence and a more complex friction system. A smaller STD indicates a more stable friction system. These two new characteristic parameters effectively exhibit the dynamic behavior of the wear process.

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Spatial and temporal scales of exposure and sensitivity drive mortality risk patterns across life stages

Ecosphere ◽

10.1002/ecs2.3552 ◽

2021 ◽

Vol 12 (6) ◽

Author(s):

Lauren L. M. Pandori ◽

Cascade J. B. Sorte

Keyword(s):

Mortality Risk ◽

Life Stages ◽

Temporal Scales ◽

Spatial And Temporal Scales

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Soil salinization monitoring method evolution at various spatial and temporal scales in arid context: a review

Arabian Journal of Geosciences ◽

10.1007/s12517-021-06557-x ◽

2021 ◽

Vol 14 (4) ◽

Author(s):

Zarai Besma ◽

Walter Christian ◽

Michot Didier ◽

Montoroi Jean Pierre ◽

Hachicha Mohamed

Keyword(s):

Soil Salinization ◽

Temporal Scales ◽

Monitoring Method ◽

Spatial And Temporal Scales

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Face Grinding Surface Quality of High Volume Fraction SiCp/Al Composite Materials

Chinese Journal of Mechanical Engineering ◽

10.1186/s10033-020-00527-2 ◽

2021 ◽

Vol 34 (1) ◽

Author(s):

Xu Zhao ◽

Yadong Gong ◽

Guiqiang Liang ◽

Ming Cai ◽

Bing Han

Keyword(s):

Friction Coefficient ◽

Surface Morphology ◽

Surface Quality ◽

Volume Fraction ◽

High Volume ◽

Spindle Speed ◽

High Volume Fraction ◽

Machining Parameters ◽

Al Composite

AbstractThe existing research on SiCp/Al composite machining mainly focuses on the machining parameters or surface morphology. However, the surface quality of SiCp/Al composites with a high volume fraction has not been extensively studied. In this study, 32 SiCp/Al specimens with a high volume fraction were prepared and their machining parameters measured. The surface quality of the specimens was then tested and the effect of the grinding parameters on the surface quality was analyzed. The grinding quality of the composite specimens was comprehensively analyzed taking the grinding force, friction coefficient, and roughness parameters as the evaluation standards. The best grinding parameters were obtained by analyzing the surface morphology. The results show that, a higher spindle speed should be chosen to obtain a better surface quality. The final surface quality is related to the friction coefficient, surface roughness, and fragmentation degree as well as the quantity and distribution of the defects. Lower feeding amount, lower grinding depth and appropriately higher spindle speed should be chosen to obtain better surface quality. Lower feeding amount, higher grinding depth and spindle speed should be chosen to balance grind efficiently and surface quality. This study proposes a systematic evaluation method, which can be used to guide the machining of SiCp/Al composites with a high volume fraction.

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Challenges in urban flood management: travelling across spatial and temporal scales

Journal of Flood Risk Management ◽

10.1111/j.1753-318x.2008.00010.x ◽

2008 ◽

Vol 1 (2) ◽

pp. 81-88 ◽

Cited By ~ 85

Author(s):

C. Zevenbergen ◽

W. Veerbeek ◽

B. Gersonius ◽

S. Van Herk

Keyword(s):

Flood Management ◽

Temporal Scales ◽

Urban Flood ◽

Spatial And Temporal Scales

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Characteristics of the east Mediterranean dust variability on small spatial and temporal scales

Atmospheric Environment ◽

10.1016/j.atmosenv.2015.08.058 ◽

2015 ◽

Vol 120 ◽

pp. 51-60 ◽

Cited By ~ 10

Author(s):

Yuval ◽

Meytar Sorek–Hamer ◽

Amnon Stupp ◽

Pinhas Alpert ◽

David M. Broday

Keyword(s):

East Mediterranean ◽

Temporal Scales ◽

Spatial And Temporal Scales

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Preface: European lagoons—need for further comparison across spatial and temporal scales

Hydrobiologia ◽

10.1007/s10750-008-9463-4 ◽

2008 ◽

Vol 611 (1) ◽

pp. 1-4 ◽

Cited By ~ 13

Author(s):

A. Razinkovas ◽

Z. Gasiūnaitė ◽

P. Viaroli ◽

J. M. Zaldívar

Keyword(s):

Temporal Scales ◽

Spatial And Temporal Scales

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Impacts of beaver dams on hydrologic and temperature regimes in a mountain stream

Hydrology and Earth System Sciences ◽

10.5194/hess-19-3541-2015 ◽

2015 ◽

Vol 19 (8) ◽

pp. 3541-3556 ◽

Cited By ~ 25

Author(s):

M. Majerova ◽

B. T. Neilson ◽

N. M. Schmadel ◽

J. M. Wheaton ◽

C. J. Snow

Keyword(s):

Overland Flow ◽

Stream Temperature ◽

Mountain Stream ◽

Complex Flow ◽

Temporal Scales ◽

Spatial And Temporal Scales ◽

Beaver Dam ◽

Temperature Regimes ◽

Continuous Stream ◽

Beaver Dams

Abstract. Beaver dams affect hydrologic processes, channel complexity, and stream temperature in part by inundating riparian areas, influencing groundwater–surface water interactions, and changing fluvial processes within stream systems. We explored the impacts of beaver dams on hydrologic and temperature regimes at different spatial and temporal scales within a mountain stream in northern Utah over a 3-year period spanning pre- and post-beaver colonization. Using continuous stream discharge, stream temperature, synoptic tracer experiments, and groundwater elevation measurements, we documented pre-beaver conditions in the first year of the study. In the second year, we captured the initial effects of three beaver dams, while the third year included the effects of ten dams. After beaver colonization, reach-scale (~ 750 m in length) discharge observations showed a shift from slightly losing to gaining. However, at the smaller sub-reach scale (ranging from 56 to 185 m in length), the discharge gains and losses increased in variability due to more complex flow pathways with beaver dams forcing overland flow, increasing surface and subsurface storage, and increasing groundwater elevations. At the reach scale, temperatures were found to increase by 0.38 °C (3.8 %), which in part is explained by a 230 % increase in mean reach residence time. At the smallest, beaver dam scale (including upstream ponded area, beaver dam structure, and immediate downstream section), there were notable increases in the thermal heterogeneity where warmer and cooler niches were created. Through the quantification of hydrologic and thermal changes at different spatial and temporal scales, we document increased variability during post-beaver colonization and highlight the need to understand the impacts of beaver dams on stream ecosystems and their potential role in stream restoration.

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