Thermomechanical fatigue life investigation of an ultra-large mining dump truck tire

The cost benefits associated with the use of heavy mining machinery in the surface mining industry has led to a surge in the production of ultra-large radial tires with rim diameters in excess of 35 in. These tires experience fatigue failures in operation. The use of reinforcing fillers and processing aids in tire compounds results in the formation of microstructural inhomogeneity in the compounds and may serve as sources of crack initiation in the tire. Abrasive material cutting is another source of cracks in tires used in mining applications. It suffices, then, to assume that every material plane in the tire consists of a crack precursor of some known size likely to nucleate under the tire\u27s duty cycle loads. This assumption eliminates the need for prior knowledge of the location and geometry of crack features to be explicitly included in a tire finite element model, overcoming the key limitations of previous approaches. In this study, a rainflow counting algorithm is used to consistently count strain reversals present in the complex multiaxial variable amplitude duty-cycle loads of the tire to assess fatigue damage on its material planes. A critical plane analysis method is then used to account for the non-proportional loading on the tire material planes in order to identify the plane with the highest fatigue damage. The size of the investigated tire is 56/80R63, and it is typically fitted to ultra-class trucks with payload capacities in excess of 325 tonne (360 short ton). Experimental data obtained from extracted specimens of the tire were used to characterize the stress-strain and fatigue behavior of the tire finite element model in ABAQUS. A sequentially coupled thermomechanical rolling analysis of the tire provided stress, strains, and temperature data for the computation of the tire\u27s component fatigue performance in the rubber fatigue solver ENDURICA CL. The belt endings (tire shoulder), lower sidewall, and tread lug corners are susceptible to crack initiation and subsequent failure due to high stresses. This pioneering research effort contributes to the body of knowledge in tire durability issues in relation to mining applications. In addition, it provides a basis for off-road tire compounders and developers to design durable tires to minimize tire operating costs in the mining industry --Abstract, page iii

CTC Newsletter- Fall 1982

https://neiudc.neiu.edu/ctcnews/1010/thumbnail.jp

Costly Mistakes, Declining Fortunes; At Whose Detriment: An Assessment of Cocoa Cultivation in Ghana

The growth and capacity of the world’s economy has been fueled by its resource forte. Within local economies, the variations in growth and development can be potted on the basis of a country’s resource utilization and management skills; a common feature of resource crunch. This study explores the causes and the dimensions of the decline in cocoa cultivation in Ghana. The study also examines how national revenue and rural livelihoods in Ghana are dissipating as a result of the decline in cocoa cultivation. Purposive and Random sampling were applied in the selection of individuals, communities, cocoa farmers and cocoa farms for the study. Both primary and secondary data were collected. The study revealed that cocoa cultivation in Ghana is plagued with several problems to the extent that rural livelihoods and national economic wealth are dying out. Export volumes have dropped by 25.7% and government revenue from cocoa has also declined by 33.2%. The study also revealed that about four (4) million people are at the verge of losing their livelihood if current trends in cocoa cultivation continue. The study recommends the commercialisation of cocoa cultivation in Ghana as a way of managing loses and dealing with the problem of capital injection. Law enforcement, transportation, education, training and road infrastructure improvements are required in order to boost growth and cocoa cultivation in Ghana. Keywords: Cocoa, Cultivation, Farmers, Livelihood, National Revenu

Erosion And Livelihood Change In North East Ghana: A Look Into The Bowl.

The study was carried out in the Upper East Region of Ghana, Bongo District, to assess the driving causes and effects soil erosion in the District and the Region at large. While soil erosion is widely recognized as reducing environmental resource capacity to provide for the populations, few studies have explicitly measured its effects on the rural farmer and the apparent root causes of erosion in the region. Upper East Region is particularly vulnerable to the effects of soil erosion with one of the highest rates of soil erosion in Ghana

INNOVATION AND OBSTACLES IN WEST AFRICAN FIRMS: AN EVIDENCE FROM THE GHANAIAN CONTEXT

Innovation is a concept that has kept the attention of researchers worldwide. Innovation leads to product and process improvement, assists the organization to survive, grow faster, efficiently, and be more profitable than non-innovative organisations. However, the innovation level among Ghanaian firms is not yet reaching its full potential. In addition, innovative behaviour among Ghanaian enterprises is still at the infancy stage. To boost the innovation rate, it is imperative to solve the challenges and issues faced by Ghanaian firms. Innovation has become the building block of development in both developed and developing countries it is commonly agreed that innovation is the critical path towards growth and prosperity for countries as well as for individual firms. It is the key to technology adoption, creation and explains the vast difference in productivity across and within countries. However, in Africa, the case seems to have faced a challenging time due to obstacles like finance accessibility, electricity, trade regulations, land access, tax, corruption, informal sector malpractices, tax administration, political instability, transportation, and others. It is against some of these obstacles that we decided to embark on this study to help us critically investigate the effect of the barriers to firms’ growth and its effect on the degree of innovation among Ghanaian firms. To help recommend possible solutions to these obstacles. Hence, this will help facilitate firms’ growth and their degree of innovation. Keywords: Innovation, Obstacles, Firms, Ghana

Durability prediction of an ultra-large mining truck tire using an enhanced finite element method

Ultra-class mining trucks used for material haulage in rugged surface mining terrains experience premature tire fatigue failure in operation. Typical failures include belt edge separation, ply turn-up separation, and tread base and sidewall cracking. The use of reinforcing fillers and processing aids in tire compounds result in the formation of microstructural in-homogeneities in the compounds. This article presents an application of the critical plane analysis technique for predicting the fatigue life of the belt package of an ultra-large mining truck (CAT 795F) tire of size 56/80R63 in a surface coal mine. Experimental data obtained from extracted specimens (sidewall, tread, and belt edge region) of the tire are used to characterize the stress—strain and fatigue behavior of the modeled tire. The tire\u27s duty cycle stresses and strains were obtained from finite element analysis of the rolling tire in Abaqus. Fatigue life calculations were performed in the rubber fatigue solver Endurica CL. Effects of inflation pressure, tire speed, and axle load on the fatigue life of the belt package under strain-crystallizing and non-crystallizing conditions of the belt compound are discussed. Specifically, the results show the belt edges to be critical regarding crack nucleation

Methadone-induced mortality in the treatment of chronic pain: Role of QT prolongation

Methadone is increasingly prescribed for chronic pain, yet the associated mortality appears to be rising disproportionately relative to other opioid analgesics. We review the available evidence on methadone-associated mortality, and explore potential pharmacokinetic and pharmacodynamic explanations for its greater apparent lethality. While methadone shares properties of central nervous system and respiratory depression with other opioids, methadone is unique as a potent blocker of the delayed rectifier potassium ion channel (IKr). This results in QT-prolongation and torsade de pointes (TdP) in susceptible individuals. In some individuals with low serum protein binding of methadone, the extent of blockade is roughly comparable to that of sotalol, a potent QT-prolonging drug. Predicting an individual’s propensity for methadone-induced TdP is difficult at present given the inherent limitations of the QT interval as a risk-stratifier combined with the multifactorial nature of the arrhythmia. Consensus recommendations have recently been published to mitigate the risk of TdP until further studies better define the arrhythmia risk factors for methadone. Studies are needed to provide insights into the clinical covariates most likely to result in methadone-associated arrhythmia and to assess the feasibility of current risk mitigation strategies

Socio-economic and demographic disparities in ownership and use of insecticide-treated bed nets for preventing malaria among rural reproductive-aged women in northern Ghana

Background Malaria continues to be a leading cause of morbidity and mortality in most countries in Sub-Saharan Africa. Insecticide-treated bed nets (ITNs) is one of the cost-effective interventions for preventing malaria in endemic settings. Ghana has made tremendous efforts to ensure widespread ownership and use of ITNs. However, national coverage statistics can mask important inequities that demand targeted attention. This study assesses the disparities in ownership and utilization of ITNs among reproductive-aged women in a rural impoverished setting of Ghana. Methods Population-based cross-sectional data of 3,993 women between the age of 15 and 49 years were collected in seven districts of the Upper East region of Ghana using a two-stage cluster sampling approach. Bivariate and multivariate regression models were used to assess the social, economic and demographic disparities in ownership and utilization of ITN and to compare utilization rates among women in households owning at least one ITN. Results As high as 79% of respondents were found to own ITN while 62% of ITN owners used them the night preceding the survey. We identified disparities in both ownership and utilization of ITNs in wealth index, occupational status, religion, and district of residence. Respondents in the relative richest wealth quintile were 74% more likely to own ITNs compared to those in the poorest quintile (p-value< 0.001, CI = 1.29–2.34) however, they were 33% less likely to use ITNs compared to the poorest (p-value = 0.01, CI = 0.50–0.91). Conclusion Interventions aimed at preventing and controlling malaria through the use of bed nets in rural Ghana and other similar settings should give more attention to disadvantage populations such as the poor and unemployed. Tailored massages and educational campaigns are required to ensure consistent use of treated bed nets

Cost of implementing a community-based primary health care strengthening program: The case of the Ghana Essential Health Interventions Program in northern Ghana

Background The absence of implementation cost data constrains deliberations on consigning resources to community-based health programs. This paper analyses the cost of implementing strategies for accelerating the expansion of a community-based primary health care program in northern Ghana. Known as the Ghana Essential Health Intervention Program (GEHIP), the project was an embedded implementation science program implemented to provide practical guidance for accelerating the expansion of community-based primary health care and introducing improvements in the range of services community workers can provide. Methods Cost data were systematically collected from intervention and non-intervention districts throughout the implementation period (2012–2014) from a provider perspective. The step-down allocation approach to costing was used while WHO health system blocks were adopted as cost centers. We computed cost without annualizing capital cost to represent financial cost and cost with annualizing capital cost to represent economic cost. Results The per capita financial cost and economic cost of implementing GEHIP over a three-year period was $1.79, and$1.07 respectively. GEHIP comprised only 3.1% of total primary health care cost. Health service delivery comprised the largest component of cost (37.6%), human resources was 28.6%, medicines was 13.6%, leadership/governance was 12.8%, while health information comprised 7.5% of the economic cost of implementing GEHIP. Conclusion The per capita cost of implementing the GEHIP program was low. GEHIP project investments had a catalytic effect that improved community-based health planning and services (CHPS) coverage and enhanced the efficient use of routine health system resources rather than expanding overall primary health care costs