A Review of Important Factors Affecting Treadwear

1992 ◽  
Vol 65 (3) ◽  
pp. 601-659 ◽  
Author(s):  
Alan G. Veirh
Keyword(s):  
Environmental Factors ◽  
Aspect Ratio ◽  
Carbon Black ◽  
Ambient Temperature ◽  
Complex Function ◽  
Body Type ◽  
Short Term ◽  
Cyclic Pattern ◽  
Generic Type

Abstract For any specific tire use condition, treadwear performance is influenced by three main factor categories: (1), tire construction; (2), tread materials; and (3), environmental and vehicle use conditions. Tire construction factors are—generic type (bias, belted-bias, radial), tread pattern groove void level, and geometric shape, i.e., aspect ratio. The relative importance of nominal variations in each of these factors for treadwear performance is 100, 46, and 39, respectively. Performance improves for a change from bias to radial; high to low groove void; and high to low aspect ratio. The combined influence of generic type, aspect ratio, and other internal construction features (e.g., belt stiffness) can be described by one parameter, the ratio of the treadband edgewise bending stiffness, KBo and the carcass (spring) stiffness, Kc. Treadlife is a direct linear function of this ratio. Treadwear compound or material performance is a function of the rubber glass-transition temperature (weighted avg. for blends), and the degree of reinforcement which is dictated by the carbon-black structure, surface area, and surface chemistry, in addition to the amount of black in the compound. The effect of each of these is a complex function of (i), the severity of tire use (e.g., cornering intensities) and (ii), the long term (seasonal) and short term (daily) environmental factors of pavement microtexture (0.01 mm scale) and ambient temperature. Precipitation directly influences microtexture level through a chemical etching of the pavement aggregate particles. Increased Tg and carbon-black reinforcement can improve or degrade treadwear performance depending on the external factors of pavement microtexture and ambient temperature and also on the general severity of tire use. Treadwear performance is also influenced by the degradation characteristics of the tread compound. Degradation propensity is influenced by crosslink structure and general susceptibility to oxidation. High wear rates are encountered for compounds cured with high-sulfur cure systems (high crosslink polysulfide content) and with low levels of antioxidant. Substantial evidence exists to support a “two-mechanism” theory of rubber abrasion. Mechanism 1 is predominant when the rubber tread element experiences highly elastic surface deformations induced by frictional contact with the pavement asperities. Rubber particles are removed by a tear-tensile rupture process. Mechanism 2 is predominant when the rubber experiences a plastic or rigid body type of contact with the pavement asperities. This contact exists on a smaller scale (reduced deformation domain) and particles are removed by an abrasive-cutting action. Mechanism 1 is called “E-Wear”; Mechanism 2 is called “P-Wear”. E-wear is favored by high temperatures, low microtexture pavements, soft (low Tg) compounds with low reinforcement levels. P-wear is favored by high microtexture, low ambient temperatures, hard (high Tg) compounds with high levels of reinforcement. The confusing treadwear performance frequently encountered for compounds—when tested at different locations, at different times, with substantial treadwear index changes, and outright reversals—can be rationally explained on the basis of a shift of the predominant mechanism. These shifts are due to changes in the environmental factors and tire-use severity as tires are tested at different locations over varying seasonal periods. Microtexture follows a seasonal cyclic pattern; high in winter and low in summer. Ambient temperature follows an opposite cyclic pattern. Short term changes (daily ) in both microtexture and temperature occur within the long-term seasonal periods. These changes have to be accommodated in interpreting treadwear performance.

scholarly journals The Dimension of Time in Host-Microbiome Interactions

mSystems ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Giulia T. Uhr ◽  
Lenka Dohnalová ◽  
Christoph A. Thaiss
Keyword(s):  
Microbial Community ◽  
Environmental Factors ◽  
Temporal Dynamics ◽  
Therapeutic Strategies ◽  
Intestinal Microbiome ◽  
Short Term ◽  
Intestinal Microbial Community ◽  
Intermediate States ◽  
Different Time Scales

ABSTRACT The intestinal microbiota contains trillions of commensal microorganisms that shape multiple aspects of host physiology and disease. In contrast to the host’s genome, the microbiome is amenable to change over the course of an organism’s lifetime, providing an opportunity to therapeutically modulate the microbiome’s impact on human pathophysiology. In this Perspective, we highlight environmental factors that regulate the temporal dynamics of the intestinal microbiome, with a particular focus on the different time scales at which they act. We propose that the identification of transient and intermediate states of microbiome responses to perturbations is essential for understanding the rules that govern the behavior of this ecosystem. The delineation of microbiome dynamics is also helpful for distinguishing cause and effect in microbiome responses to environmental stimuli. Understanding the dimension of time in host-microbiome interactions is therefore critical for therapeutic strategies that aim at short-term or long-term engineering of the intestinal microbial community.

scholarly journals Association between ambient temperature and cognitive function in a community-dwelling elderly population: a repeated measurement study

BMJ Open ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. e049160
Author(s):  
Yuan-Ting C Lo ◽  
Wei-Peng Su ◽  
Shu-Hsuan Mei ◽  
Yann-Yuh Jou ◽  
Han-Bin Huang
Keyword(s):  
Older Adults ◽  
Cognitive Impairment ◽  
Cognitive Function ◽  
Ambient Temperature ◽  
Air Temperature ◽  
Community Dwelling ◽  
Secondary Outcome ◽  
Short Term ◽  
Temperature Exposure

ObjectivesEvidence on the associations between short-term and long-term air temperature exposure and cognitive function in older adults, particularly those in Asia, is limited. We explored the relationships of short-term and long-term air temperature exposure with cognitive function in Taiwanese older adults through a repeated measures survey.Design and settingWe used data the ongoing Taiwan Longitudinal Study on Aging, a multiple-wave nationwide survey.ParticipantsWe identified 1956, 1700, 1248 and 876 older adults in 1996, 1999, 2003 and 2007, respectively.Primary and secondary outcome measuresParticipants’ cognitive function assessment was based on the Short Portable Mental Status Questionnaire. We calculated the temperature moving average (TMA) for temperature exposure windows between 1993 and 2007 using data from air quality monitoring stations, depending on the administrative zone of each participant’s residence. Generalised linear mixed models were used to examine the effects of short-term and long-term temperature changes on cognitive function.ResultsShort-term and long-term temperature exposure was significantly and positively associated with moderate-to-severe cognitive impairment, with the greatest increase in ORs found for 3-year TMAs (OR 1.247; 95% CI 1.107 to 1.404). The higher the quintiles of temperature exposure were, the higher were the ORs. The strongest association found was in long-term TMA exposure (OR 3.674; 95% CI 2.103 to 6.417) after covariates were controlled for.ConclusionsThe risk of mild cognitive impairment increased with ambient temperature in community-dwelling older adults in Taiwan.

scholarly journals Pengaruh Penuaan Aspal Pada Karakteristik Campuran Beton Aspal Lapis Aus AC – WC

2020 ◽  
pp. 47-56
Author(s):  
M. Mashuri ◽  
R. Rahman
Keyword(s):  
Environmental Factors ◽  
Air Temperature ◽  
Asphalt Concrete ◽  
Aging Process ◽  
Short Term ◽  
The Road ◽  
Service Period ◽  
Asphalt Content ◽  
Pavement Layers

The aging process of asphalt in the pavement layers of asphalt concrete road occurs when mixing in the Asphalt Mixing Plant and during the road service period. The asphalt aging process when mixing is called short-term aging and aging during the road service period is called long-term aging. AC - WC mixture is a wear layer and it is on the top layer of the surface which allows characteristics change that are influenced by several environmental factors (air, temperature and sunlight). This study aims to know the effect of asphalt aging on the characteristics of AC - WC mixture with Marshall method on some asphalt content  that are 4.5%, 5.0%, 5.5%, 6.0%, 6, 5% and 7.0%. For testing on short-term aging (Short - Term Oven Aging, STOA) is by testing the mixture specimen AC - WC at 135o C before solidified for 4 hours and for long-term aging (Long - Term Oven Aging, LTOA) was carried out by testing the mixture specimen AC - WC at 85o C for 2 - 5 days. The results of this study found that asphalt aging had an effect on the characteristics of AC - WC mixture. Values of density, VFB, stability, flow tend to decrease with age. While VIM and VMA values tend to increase with age. Aging caused the mixture to became more rigid.

scholarly journals Favourable changes in physical working conditions and the risk of all-cause sickness absence: a pseudo-experiment

2019 ◽  
Vol 30 (2) ◽  
pp. 253-259
Author(s):  
Rahman Shiri ◽  
Aapo Hiilamo ◽  
Olli Pietiläinen ◽  
Minna Mänty ◽  
Ossi Rahkonen ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Sickness Absence ◽  
Working Conditions ◽  
Negative Binomial ◽  
Physical Workload ◽  
Health Study ◽  
Baseline Survey ◽  
Short Term

Abstract Background We determined whether favourable changes in physical workload and environmental factors reduce sickness absence (SA) days using observational cohort data as a pseudo-experiment. Methods The data from the Finnish Helsinki Health Study included three cohorts of employees of the City of Helsinki [2000/2002–07 (N = 2927), 2007–12 (N = 1686) and 2012–17 (N = 1118), altogether 5731 observations]. First, we estimated the propensity score of favourable changes (reduction in exposures) in physical workload and environmental factors during each 5-year follow-up period on the baseline survey characteristics using logistic regression. Second, we created and stabilized inverse probability of treatment weights for each participant using the propensity scores. Lastly, we used generalized linear model and fitted negative binomial regression models for over-dispersed count data to estimate whether the favourable changes decrease the risk of short-term (1–3 days), intermediate-term (4–14 days) and long-term (>14 days) SA using employer’s register data. Results During a 5-year follow-up, 11% of the participants had favourable changes in physical workload factors, 13% in environmental factors and 8% in both factors. The incidence of short-term, intermediate-term and long-term SA were lower in employees with favourable workplace changes compared with those without such changes. The reductions were largest for long-term SA. Reporting favourable changes in both workload and environmental factors reduced the number of SA days by 41% within 1 year after the changes and by 32% within 2 years after the changes. Conclusion This pseudo-experimental study suggests that improving physical working conditions reduces SA.

scholarly journals Effect of Nucleating Additives on Short- and Long-Term Tensile Strength and Residual Stresses of Welded Polypropylene Samples

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2965
Author(s):  
Andrea Wübbeke ◽  
Volker Schöppner ◽  
Theresa Arndt ◽  
Jan-Ole Maras ◽  
Marcus Fitze ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Residual Stresses ◽  
Weld Seam ◽  
Nucleating Agent ◽  
Hole Drilling ◽  
Nucleating Agents ◽  
Short Term ◽  
Short And Long Term

Additives such as nucleating agents are often used in the processing of plastic products not only for improving production efficiency but also for enhancing mechanical performance. In this work, the short- and long-term tensile strength, the morphology as well as the residual stresses of the welded polypropylene (PP) samples with different fillers (carbon black and special beta-nucleating agents) and different dimensionless joining paths are analyzed. Results obtained are then compared with those that are representative of the initial, filler-free samples. It is shown that, upon using the special beta-nucleating agent, superior long-term tensile strength can be achieved compared to the samples without additives or with carbon black agent (e.g., for the dimensionless joining path of 0.95, the long-term tensile strength of a PP nature sample is characterized by around 400 MPa, whereas by adding beta-nucleating agent 1% the value can be increased by 400% to reach around 2050 MPa). However, adding beta-nucleating agent 1% yields inferior short-term tensile strength. The hole drilling method (HDM) is used for the analysis of residual stresses. It is found that the residual stresses in the weld seam are characterized by low values of the tensile stresses. The residual stresses in the weld seam also can be converted from tensile into compressive stresses by adding the beta nucleating agent. However, this has the disadvantage that with a higher proportion by weight of the beta nucleating agent, the short-term tensile strength of the welded joint becomes lower than that of the other tested bonds.

The Possible Interaction of Harderian Material and Saliva for Thermoregulation in the Mongolian Gerbil, Meriones Unguiculatus

1989 ◽  
Vol 68 (1) ◽  
pp. 3-10 ◽  
Author(s):  
Mitzie Grant ◽  
Del Thiessen
Keyword(s):  
Ambient Temperature ◽  
Mongolian Gerbil ◽  
Evaporative Cooling ◽  
Meriones Unguiculatus ◽  
High Ambient Temperature ◽  
Short Term ◽  
Ambient Temperatures ◽  
Saliva Production ◽  
Thermoregulatory Reactions

Self-grooming in Meriones unguiculatus is associated with saliva spread and the release and spread of Harderian material from the external nares. Saliva spread results in evaporative cooling and Harderian spread insulates the pelage. Two experiments tested the predictions that (1) saliva production and Harderian material decrease systematically following a self-groom, (2) high ambient temperature (34°C) increases saliva production but decreases Harderian release, and (3) low ambient temperature (7°C) decreases saliva production but increases Harderian release. The predictions were generally confirmed, suggesting that short-term and long-term thermoregulatory reactions are differentially affected by ambient temperatures. Thus, an animal will tend to emphasize saliva production when evaporative cooling is needed and will exaggerate Harderian release when insulation of the pelage is required.

scholarly journals Larval developmental temperature and ambient temperature affect copulation duration in a seed beetle

Behaviour ◽  
2018 ◽  
Vol 155 (1) ◽  
pp. 69-82 ◽  
Author(s):  
R. Vasudeva ◽  
D.C. Deeming ◽  
P.E. Eady
Keyword(s):  
Ambient Temperature ◽  
Callosobruchus Maculatus ◽  
Copulation Duration ◽  
Short Term ◽  
Developmental Temperature ◽  
Effects Of Temperature ◽  
Kinetic Effects ◽  
Development Temperature ◽  
Copulatory Behaviour

Abstract The effects of temperature on cellular, systemic and whole-organism processes can be short-term, acting within seconds or minutes of a temperature change, or long-term, acting across ontogenetic stages to affect an organism’s morphology, physiology and behavioural phenotype. Here we examine the effect of larval development temperature on adult copulatory behaviour in the bruchid beetle, Callosobruchus maculatus. As predicted by temperature’s kinetic effects, copulation duration was longest at the lowest ambient temperature. However, where ambient temperature was fixed and developmental temperature experimentally varied, males reared at the highest temperature were least likely to engage in copulation, whilst those reared at the lowest temperature copulated for longer. Previous research has shown males reared at cooler temperatures inseminate fewer sperm. Thus, in this species longer copulations are associated with reduced sperm transfer. We argue that knowledge of preceding ontogenetic conditions will help to elucidate the causes of variation in copulatory behaviour.

On Managing Variable Marine Fisheries

1987 ◽  
Vol 44 (7) ◽  
pp. 1370-1375 ◽  
Author(s):  
Wayne M. Getz ◽  
Robert C. Francis ◽  
Gordon L. Swartzman
Keyword(s):  
Environmental Factors ◽  
Density Dependence ◽  
Sustainable Yield ◽  
Hard Problem ◽  
Marine Fisheries ◽  
Short Term ◽  
Stock Recruitment ◽  
Over Exploitation ◽  
The Hard Problem

Marine fisheries are difficult to manage because they are highly variable; yet the stock must be protected from over exploitation and possible collapse. Here we demonstrate that the most important source of uncertainty in estimating long-term productivity of a fishery is the degree of density dependence in the stock–recruitment relationship and not the environmental factors that influence annual recruitment rates. We evaluate the performance of three harvest policies in managing dynamically contrasting fisheries and conclude that close to maximum expected sustainable yield can be obtained by policies that have very different implications for short-term yields. In stochastic fisheries, the variability inherent in the stock can be ignored in determining optimal effort levels or it can be transferred into the fishery by allowing yield and effort levels to vary considerably. Thus it is relatively easy for the manager to ensure long-term maximization of yield. The hard problem is finding a suitable compromise between short-term stability of the fishery and long-term viability of the stock.

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