EXPERIMENTAL FAILURE INVESTIGATION OF AN AIRCRAFT NOSE LANDING GEAR

In 1994, sets of aircraft were introduced into the Nigerian Aviation Industry for training of pilots. The nose wheels of some of the aircraft collapsed particularly during hard landings. The failure modes include complete fracture of the landing gear from the firewall and the buckling. This is the thrust for this study which is aimed at ascertaining the cause and mechanism of failure experimentally with a view to preventing future occurrence. Fractography of the failed samples was carried out and the fractograph showed high energy fracture – beach marks, initiation sites and the propagation area on the failure surface which indicates fatigue failure. Chemical analysis of the landing gear component showed medium carbon steel of the tough grade instead of spring steel. Experimental analysis entailed the characterization of fractured parts of the undamaged and failed nose wheel struts by determining the mechanical properties and examining the structural morphology of test samples. Fatigue tests revealed high cycle low stress fatigue in the failed material. Microstructural examination showed intermetallic inclusions within the microstructure of the material which acted as stress raisers causing crack initiation and eventually fatigue fracture

Inhibitive characteristics of cetylpyridinium chloride and potassium chromate addition on type A513 mild steel in acid/chloride media

Linear polarization resistance and open circuit potential methods were used to assess the inhibitive and adsorption behaviour of Potassium chromate (K2CrO4) and Cetylpyridinium chloride (CPC) on mild steel (MS) in HCl/NaCl solution. Results obtained show that K2CrO4 and CPC inhibit MS significantly against massive degradation. However, under open circuit potential method, inhibition efficiency of K2CrO4 decreased at higher concentration. The synergistic effect of both inhibitors is positive on the protection of mild steel against corrosion. An inhibitive efficiency of over 60% was recorded for the combined admixture. Morphological study showed that the exposed steel with the presence of K2CrO4 and CPC possess some corrosion product with lesser pitting effect compare to unprotected steel with severe surface deterioration and uniform corrosion degradation. The corrosion inhibition performance of K2CrO4 and CPC on mild steel surface was found to follow Langmuir adsorption isotherm model

Assessment of the impact of abattoir effluent on the quality of groundwater in a residential area of Omu‑Aran, Nigeria

Background: Water pollution from abattoir effluents may create substantial environmental and public health hazards. Available literature is scanty on the quality of groundwater located near abattoirs in tropical developing countries like Nigeria. This study, therefore, accessed the impact of abattoir activities on the quality of groundwater in Omu-Aran Nigeria. Methods: A total of eighteen water samples were taken from five privately own wells and one control well located at varying distances and elevations to the abattoir. The physicochemical characteristics of the water were determined using the standard methods. Data were analyzed using descriptive statistics and ANOVA. Results: The mean values of parameters in the water samples collected from the studied wells ranged from 5.80 ± 0.20 to 7.23 ± 0.55 mg/L, 12.0 ± 1.0 to 26.0 ± 2.0 mg/L, 0.06 ± 0.02 to 0.16 ± 0.02 mg/L and 208.0 ± 24.25 to 254.67 ± 12.22 cfu/mL for dissolved oxygen, biological oxygen demand, lead and total coliforms, respectively. There was a significant difference in the quality of water from the studied and control wells in the parameters except that of total coliform. The quality of the groundwater improved with increasing distance from the abattoir. Conclusions: Findings revealed that abattoirs have the potential to impact the quality of groundwater. Therefore, careful consideration is required when choosing a location for siting new abattoirs. For existing ones, particularly those close to residential areas, effective pollution control measures should be put in place to protect groundwater

Effect of bath ionic strength on adhesion and tribological properties of pure nickel and nickel composite coatings

The effect of electrolytic chemical concentration on wear-resistant, corrosion-resistant, adhesion and wettability properties of pure nickel and nickel-alumina composite coatings has been investigated in this paper. Coatings were electroplated over steel substrates under constant pulse conditions using pulse electrodeposition technique. Corrosion-resistant results show that the anti-corrosion properties are increasing with medium concentration both for pure nickel and nickel-alumina composite coating. For anti-wear properties the medium concentration showed increasing trend in case of pure nickel coatings but decreased in nickel-alumina composite coatings. In composite coating the higher and low concentrations of electrolyte showed the higher wear resistance properties. Furthermore, the influence of electrolyte concentration on changing surface morphologies, mechanical, wettability and adhesion properties have been investigated and reported here. Surface morphologies of the coatings were examined using scanning electron microscopy and energy-dispersive spectroscopy. Surface mapping and wear analyses were conducted through 3D white light interferometry

Direct bioleaching of Zinc using manihot esculenta crantz (cassava) extract without additives

Abstract: The advent and development of new technologies that will provide better yields, cleaner and a safer environment is a global challenge for the researchers. Traditional solvents used in extraction of minerals are at many times hazardous thereby constituting threats to the ecology. The work reports the direct bioleaching of zinc sourced from Abakaliki-Ishiagwu complex zinc sulphide ore deposit. The sphalerite ore is predominant in Zn with other associated metals Pb, Cu, Fe, Ni, Sb, As, Cd, Au, V, Co, Ag, K, Al and Ca. It covers the pre extraction processes of mineral comminution (crushing and grinding); separation by froth flotation; and roasting. Agro-cyanide was extracted from cassava plant (Manihot esculenta Crantz) leaves and was used as leachant without any additive. The result of atomic absorption spectrometry (AAS) analysis of the leached liquor (pregnant solution) shows that lead, copper and iron in addition to Zinc, were obtained from the leached ore roast at 149.25 ppm (Zn), 79.25 ppm (Pb), 0.25 ppm (Cu) and 4.25 ppm (Fe) extraction after 21 days. Elongated contact of ZnO ore is not encouraging for Zn extraction as there is a decline in the quantity of Zn, Fe and Cu as the leaching time (days) increases. The mechanism of the Leach next faction is yet to be fully ascertained, hence the need for further work in the area

Logistic support provided to Australian disaster medical assistance teams: results of a national survey of team members

Background: It is likely that calls for disaster medical assistance teams (DMATs) continue in response to international disasters. As part of a national survey, the present study was designed to evaluate the Australian DMAT experience and the need for logistic support.\ud \ud Methods: Data were collected via an anonymous mailed survey distributed via State and Territory representatives on the Australian Health Protection Committee, who identified team members associated with Australian DMAT deployments from the 2004 Asian Tsunami disaster.\ud \ud Results: The response rate for this survey was 50% (59/118). Most of the personnel had deployed to the South East Asian Tsunami affected areas. The DMAT members had significant clinical and international experience. There was unanimous support for dedicated logistic support with 80% (47/59) strongly agreeing. Only one respondent (2%) disagreed with teams being self sufficient for a minimum of 72 hours. Most felt that transport around the site was not a problem (59%; 35/59), however, 34% (20/59) felt that transport to the site itself was problematic. Only 37% (22/59) felt that pre-deployment information was accurate. Communication with local health providers and other agencies was felt to be adequate by 53% (31/59) and 47% (28/59) respectively, while only 28% (17/59) felt that documentation methods were easy to use and reliable. Less than half (47%; 28/59) felt that equipment could be moved easily between areas by team members and 37% (22/59) that packaging enabled materials to be found easily. The maximum safe container weight was felt to be between 20 and 40 kg by 58% (34/59).\ud \ud Conclusions: This study emphasises the importance of dedicated logistic support for DMAT and the need for teams to be self sufficient for a minimum period of 72 hours. There is a need for accurate pre deployment information to guide resource prioritisation with clearly labelled pre packaging to assist access on site. Container weights should be restricted to between 20 and 40 kg, which would assist transport around the site, while transport to the site was seen as problematic. There was also support for training of all team members in use of basic equipment such as communications equipment, tents and shelters and water purification systems

International research collaboration during the pandemic: Team formation, challenges, strategies and achievements of the African Translational Research Group

This paper discusses multidisciplinary international research collaboration team formation during the COVID-19 pandemic, challenges faced, strategies adopted, achievements and dynamics in the implementation of research on Coronavirus disease-2019 (COVID-19), by the African Translational Research Group (ATReG). The paper also discusses the lessons learnt and future opportunities for global collaborative research. In-depth virtual interviews were conducted with consenting members of ATReG. Questions were designed to provide rich, deep, and insightful opinions, lived experiences and perspectives of ATReG group members on group formation, challenges, strategies and achievements. Interview data was transcribed and analysed thematically, and the results were presented with important quotations presented. The ATReG consisted of English (n = 13) and French (n = 1) speaking sub-Saharan African (SSA) researchers who specialise in public health, epidemiology, optometry, information technology, supply chain management, psychiatry, community health, general medical practice, nutrition and biostatistics. Most members of the group reported an informal but well-coordinated structure of the group. Formed during the pandemic, all group meetings were held online, and many members are yet to meet each other in person. The group collected data from Africans and published 10 peer reviewed journal articles on COVID-19 within two years. It presented in international conferences, engaged with the media and the public and was awarded a national competitive funding in Nigeria all of which which contributed to career progression and academic promotion of some members. There have been challenges in sustaining the research collaboration and maintaining productivity. Challenges include difficulties meeting deadlines and obtaining funding for research activities. However, these challenges have been addressed through a collaborative problem-solving approach. The study found the need for operational and methodological flexibility, centralised coordination, and established funding sources as being essential for long term sustainability and performance of the group. The ATReG’s objective of providing useful data on COVID-19 and generating useful knowledge about COVID-19 in SSA has been achieved. In such a multi-disciplinary international collaborative team relaiant on the online medium to operate, the experiences and challenges can be a model for learning for researchers intending to form international multidisciplinary collaborative groups. Nonetheless, there are still many important areas of research which ATReG will continue to pursue

Swift trust and commitment: the missing links for humanitarian supply chain coordination?

Coordination among actors in a humanitarian relief supply chain decides whether a relief operation can be or successful or not. In humanitarian supply chains, due to the urgency and importance of the situation combined with scarce resources, actors have to coordinate and trust each other in order to achieve joint goals. This paper investigated empirically the role of swift trust as mediating variable for achieving supply chain coordination. Based on commitment-trust theory we explore enablers of swift-trust and how swift trust translates into coordination through commitment. Based on a path analytic model we test data from the National Disaster Management Authority of India. Our study is the first testing commitment-trust theory (CTT) in the humanitarian context, highlighting the importance of swift trust and commitment for much thought after coordination. Furthermore, the study shows that information sharing and behavioral uncertainty reduction act as enablers for swift trust. The study findings offer practical guidance and suggest that swift trust is a missing link for the success of humanitarian supply chains

Emergency logistics for wildfire suppression based on forecasted disaster evolution

This paper aims to develop a two-layer emergency logistics system with a single depot and multiple demand sites for wildfire suppression and disaster relief. For the first layer, a fire propagation model is first built using both the flame-igniting attributes of wildfires and the factors affecting wildfire propagation and patterns. Second, based on the forecasted propagation behavior, the emergency levels of fire sites in terms of demand on suppression resources are evaluated and prioritized. For the second layer, considering the prioritized fire sites, the corresponding resource allocation problem and vehicle routing problem (VRP) are investigated and addressed. The former is approached using a model that can minimize the total forest loss (from multiple sites) and suppression costs incurred accordingly. This model is constructed and solved using principles of calculus. To address the latter, a multi-objective VRP model is developed to minimize both the travel time and cost of the resource delivery vehicles. A heuristic algorithm is designed to provide the associated solutions of the VRP model. As a result, this paper provides useful insights into effective wildfire suppression by rationalizing resources regarding different fire propagation rates. The supporting models can also be generalized and tailored to tackle logistics resource optimization issues in dynamic operational environments, particularly those sharing the same feature of single supply and multiple demands in logistics planning and operations (e.g., allocation of ambulances and police forces). © 2017 The Author(s