Advanced Materials Research Vols. 62-64

Abstract: This paper considers the scheduling problem of minimizing two criteria (bi criteria) at a time. The challenge of how to evaluate solution methods for bicriteria problems was first addressed. Then, two important issues of skewness (arising when the values of one criterion is a multiple of the other) and dimensional conflict (arising when the two criteria are not of the same unit) were tackled through a proposed normalization procedure. The methodology for determining the minimum and maximum possible values of the two criteria was also demonstrated.

Abstract: The keyboard layout proposed by Dvorak has been evaluated and improved by CADWORK. Data prepared with characters of the Dvorak layout were fed into CADWORK to search for improvement. The criterion employed by CADWORK for evaluation is the cycle time simulated using methods analysis of operations data. An improved layout was generated yielding a cycle time of 616.09 TMU while the Dvorak layout yielded a time of 622.69 TMU. A test to determine acceptability of the CADWORK improved layout using experienced keyboard users indicated that some participants typed faster with the CADWORK layout than others using the Dvorak layout.

Abstract: The use of Material Requirement Planning (MRP) and the evaluation of raw materials using Computer to aid the planning of a job shop have been undertaken. Raw Material Planning (MRP) models and computer programme (Visual Basic) to automatically generate the result was developed. A typical job shop industry was used to test the validity of the model and computer programme developed. It is found readily useful in a developed and developing countries where the situation prevails. The result shows an improvement upon the vigorous manual method used in the time part, and minimizes the service level to the firm’s customer and investment in inventory.

Abstract: Lagos state is the commercial and financial capital of Nigeria. It is a coastal city with a population of 12 million and covers 2000 square kilometers. The road network extends over 2700 km with a vehicle density of 740 vehicles per kilometer. It consumes over 85% of petroleum products imported into the country. It has no rail or sea mass transit system and all movements of people and goods are by road. This has created a major traffic Management challenge and government intervention is the establishment of the Lagos State Traffic Management Authority( LASTMA). To understand the structure, strength, and weaknesses of the authority, the enabling law and accident statistics, were obtained from the Authority, the Nigerian Police, and the Federal Road Safety Commission. Questionnaires were administered to drivers unions and the general public. The results were analyzed and it was discovered that conflicts across agencies, corruption and high handedness exist. It was also established that the authority has to a great extent succeeded in improving orderliness on Lagos roads. LASTMA needs to pursue an aggressive public enlightenment to change driver’s behaviors.

Abstract: An excised and dried ulna was vibrated at its balance pnoint about 42% (0.1m) along the length from the olecranon process, using an electromagnetic vibrator. The vibration was carried out in the anterior-posterior plane. The bone response to the mechanical vibration was picked up at equal intervals (0.02m) along the length of the bone in the plane of the vibration, using an accelerometer attached to the bone. From the response curve of the bone, the resonant frequencies at the various pick- up positions were identified. Analysis of the data shows that when the responses were picked up using the accelerometer at 0.02m proximal, and 0.1m distal, to the point of vibration, the excised ulna vibrated in the fundamental mode like a fixed-fixed beam at resonant frequencies of 340 Hz and 355Hz respectively. For resonant frequencies greater than 650 Hz, the ulna vibrates like a fixed-free beam and at modes greater than the fundamental. It is suggested from this study that the vibration of the long bone in the fundamental mode lends itself to detailed analysis in the use of resonant frequency method in the assessment of the bone quality.

Abstract: In this study, an attempt has been made to optimize cutting parameters (cutting speed, depth of cut, and feed rate) in conventional turning operations. A Taguchi orthogonal array (L933) was used in surface roughness optimization of a solid round bar of mild steel material. The experimental runs were randomized; two skilled machinists were involved in the turning operation using the same machining parameters. ANOVA analysis was performed to identify the percentage contribution of the factors affecting surface roughness during machining. The optimal cutting combination was determined by using the signal-to-noise ratio and the following results were obtained; speed (level 2) = 55.m/min, depth of cut (level 3) = 0.08mm, and feed rate (levels 3) = at 0.08mm/rev. A prediction of surface roughness was carried out using the optimal setting followed by a confirmatory test on the lathe. The result shows that the confirmatory runs compared favourably (96.44%) with the predicted surface roughness.

Abstract: This paper reports an examination of the stresses and pressure fields set up at various cross-sections of a material during forging operation by the weighted residual finite element method. We present the numerical solution to the one-dimensional differential equation which describes the pressures and stresses exerted on a forging. In conducting the analysis, we split the blank into a finite number of elements and apply the Bubnov-Galerkin weighted residual scheme to obtain the weighted integral form; the finite element model is then developed from this weighted integral form which is solved to yield a three-parameter polynomial solution. Using series of examples, we show that the weighted residual finite element method is capable of accurately predicting the pressures and stresses in an open die forging operation.

Abstract: In this work, we develop a finite element-finite difference method to solve the differential equation governing the radial flow of slightly compressible fluids. The finite element method is used to carry out spatial approximations so as to study the variation of fluid properties at the various nodes to which effect we divided the entire radial domain of the fluid into a mesh of four radial 1-D quadratic elements which exposes nine nodes to intense study. Time approximation is done with the aid of the Crank-Nicolson finite difference scheme.

Abstract: The paper describes the results of a numerical study using Galerkin’s finite element method on an infinitely wide slider bearing. The analysis is based upon the generalized Reynolds equation with the assumption that the pressure gradient in the lubricating film is negligible in the axial direction. Detailed results for bearing characteristics including pressure, load capacity, frictional force, frictional coefficient as a function of film thickness ratio (aspect ratio), and velocity of slider show that these parameters have a strong influence on the bearing behavior. Specifically, it has been shown that friction coefficient and frictional force increases with lower aspect ratios. Also, higher load carrying and maximum pressure is obtained with increased speed of the slider Point wise comparison of the results obtained using the Finite Element Method and that obtained with second order Finite Difference marching Method using base parameters show that the latter simulation has a maximum point wise error of 0.46% in comparison to 0.32% for Finite Element simulation. It has been shown that the Finite Element Method produces more accurate results. The results are in tabular and graphical forms.

Abstract: This paper discusses the mathematical modeling of a new improved design of the carriage bogie suspension system with emphasis on design for human comfort. The research mainly covered the shock absorbers with the aim of improving ride comfort at higher speeds. The paper focuses on how to reduce vibration transmission to the carriage while designing a railway bogie suspension damping system that is easier to maintain but does not compromise on quality with particular interest in dynamic attributes of the shock absorber. The principal research issues are introduced and looked at in the modeling and the results so obtained are used to calculate the relative transmissibility in the motion of the carriage.