Dynamic Response of Inclined Isotropic Elastic Damped Rectangular Mindlin Plate resting on Pasternak Foundation under a Moving Load

In this article, the dynamic behavior of inclined damped rectangular Mindlin plate under the influence of moving load along the mid-plate on the plate surface is considered. A numerical method is used to solve the nondimensional form of the resulting coupled partial differential equations. The desired solutions are obtained with the aid of computer program developed in conjunction with MATLAB. It is observed that the response amplitude of the plate is affected significantly by the foundation moduli. Also, the effects of the shear deformation, rotatory inertia, damping and angle of inclination of the plate, to the horizontal, are noticeable

In vitro surveillance of drug resistant falciparum malaria in north central Nigeria

Background: drug resistant malaria is spreading inexorably to areas with drug sensitive malaria parasites. This study compared the in vitro sensitivities of Plasmodium falciparum fresh parasite isolates, to some standard antimalarial drugs, in Makurdi and Masaka located over 300 km apart, in north central Nigeria. Methods: The in vitro responses of P. falciparum isolates; 43 and 39 in Makurdi and Masaka were evaluated by the standard schizonts growth inhibition assay in children aged 2-14 years. Results: The geometric mean effective concentration-EC50, EC90 and EC99 of quinine between Makurdi and Masaka differed significantly (P 0.05) was observed in the EC values of amodiaquine between the two locations. 5.13 % (2/39) of parasites at Masaka were in vitro resistant to amodiaquine with EC50 > 80 nM. The rest of the isolates were sensitive to the three antimalarial drugs at both locations. Conclusion: The results demonstrated low in vitro resistance of P. falciparum to amodiaquine in the region. Constant monitoring and intervention is needed to curtail the spread of resistance to antimalarials in Nigeria.KEY WORDS: Plasmodium falciparum, Resistance, Antimalarials, Nigeria

Design and Construction of a Scroll Compressor of an Automobile Air Conditioning System

This work focuses on the design and manufacture of a scroll compressor used in an automobile air conditioning system. A scroll compressor is a positive-displacement machine that compresses air with two interfitting spiral shaped scroll members. This compressor is of semi-hermetic design, and is quiet, reliable and efficient in performance

Role of Chloride on the Fracture Behaviour of Micro‐alloyed Steel in E20 Simulated Fuel Ethanol Environment

The need to fully comprehend the potential of pipelines in fuel ethanol applications has necessitated this study. The influence of chloride in E20 on fracture toughness and tearing resistance of micro‐alloyed steel (MAS) was studied with three‐point bend specimens. Monotonic J‐integral tests were conducted with and without chloride. Results show a decrease in fracture toughness of MAS in the presence of chloride, and a concurrent increase in its ductile tearing resistance. Fractographic examinations showed that chloride in E20 promoted quasi‐cleavage fracture

MATERIAL PERFORMANCE INVESTIGATION ON THE FAILURE OF AN AIRCRAFT (ABT-18) NOSE WHEEL STRUT

The study investigated the cause and mechanism of failure of the nose wheel strut of a trainer aircraft with respect to material selection.Various methods and tests ranging from visual examination via unaided eye and fractography, hardness tests, chemical analysis and microstructural examination were employed for the study. The results show chevrons on the fracture surface which indicates fatigue failure characteristic of brittle fracture. Also, thefractographshowsincidence of a ductile pull and high energy fracture.This is evident by the cone shape of the fractograph and the observed tear.Hardness tests results showed high discrepancy between the values of the failed and undamaged samples indicating loss of strength and ductility in the failed sample as a result of fatigue. The outcomeof chemical analysis revealed that the component is made from medium carbon steel of the tough grade instead of the required spring steel.Therefore, a major cause of the failurecan be linked to improper material specification for the nose wheel strut.The failure mechanism was further confirmed by microstructural examination which revealed fatigue cracks propagated from inclusions in the microstructure of the failed sampl

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