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

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

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

Strategic logistics outsourcing in humanitarian supply chain: a fuzzy AHP approach

This research paper investigates an under-researched topic, logistics outsourcing decision issue in the humanitarian supply chain outsourcing environment. Specifically, this research aims to identify the important factors for selecting third-party logistics(3PL) service providers in a humanitarian supply chain. This is based on literature review and interviews from logistics managers in a humanitarian sector which was evaluated with a multiple-criteria decision-making(MCDM) method called the analytical hierarchy process(AHP) under fuzzy environment. Through the use of the AHP, the relative importance of individual criteria was determined. Fuzzy-theory application of the linguistic values handles the vagueness and subjectivity of decisions. The findings of this research offer managerial insight and implication related to the use of a 3PL in the humanitarian supply chain environment to identify the possible optimal providers using a robust MCDM framework

Investigation on the Corrosion Performance of Nickel Electrodeposited Tempered Steel Substrate

ABSTRACT The investigation into the corrosion performance of nickel electroplating of low carbon steel substrate in Na 2 CO 3 environment was studied. The substrate was heat treated at various tempering temperatures, plated with nickel for 30 minutes and subjected to corrosion in Na 2 CO 3 solution. The microstructure and weight loss technique were adopted to evaluate the corrosion susceptibility of the substrate Na 2 CO 3 medium. From the results, it was observed that the rate of corrosion of nickel plated tempered low carbon steel substrates is significantly low compared to the control (i.e unplated) sample, couple with the good mechanical properties of the steel confirmed it a good option for engineering applications

Improving Visibility of Humanitarian Supply Chains Through Web-Based Collaboration

The study is intended to demonstrate the pathways for humanitarian supply chains following the well-established models of business supply chains. Information sharing is the core to increase visibility in supply chain collaboration. Sharing instant intelligent decisions between the humanitarian organizations improves the quality of humanitarian relief services as well as reduces the operational cost of the public service. With the use of prevalent web portal technology, humanitarian organization can implement web-based collaboration for e-transactions with partners and donor organizations. The benefit of web-based platform is the ability to interact and quickly form a need specific project in a short period of time by collecting a large number of volunteers, donors, and partners over the globe. The visibility of web-based monitoring of supply chain functions not only benefits the aid agencies to maintain appropriate level of stocking but also ensures high level of public services. The illustration of this study is a starting-point to develop models for humanitarian supply chain and establish future research agenda for emergency preparedness planning

Opinion and uptake of chloroquine for treatment of COVID-19 during the mandatory lockdown in the sub-Saharan African region

Background: As the search for effective treatment of coronavirus disease 2019 (COVID-19) infection continues, the public opinion around the potential use of chloroquine (CQ) in treating COVID-19 remains mixed. Aim: To examine opinion and uptake of CQ for treating COVID-19 in the sub-Saharan African (SSA) region. Setting: This study was conducted through an online survey software titled SurveyMonkey. Methods: Anonymous online survey of 1829 SSA countries was conducted during the lockdown period using Facebook, WhatsApp and authors' networks. Opinion and uptake of CQ for COVID-19 treatment were assessed using multivariate analyses. Results: About 14% of respondents believed that CQ could treat COVID-19 and of which, 3.2% took CQ for COVID-19 treatment. Multivariate analyses revealed that respondents from Central (adjusted odds ratios [aOR]: 2.54, 95% confidence interval [CI] 1.43, 4.43) and West Africa (aOR: 1.79, 95% CI 1.15, 2.88) had higher odds of believing that CQ could treat COVID-19. Respondents from East Africa reported higher odds for uptake of CQ for COVID-19 than Central, Western and Southern Africans. Knowledge of the disease and compliance with the public health advice were associated with both belief and uptake of CQ for COVID-19 treatment. Conclusion: Central and West African respondents were more likely to believe in CQ as a treatment for COVID-19 whilst the uptake of the medication during the pandemic was higher amongst East Africans. Future intervention discouraging the unsupervised use of CQ should target respondents from Central, West and East African regions