Kabwe Mulenga

This study investigated the preparedness and experience of students for the fast-paced convergence of ICT and higher education. Overall, 366 distance students with a history of self-directed learning through correspondence courses were profiled using structured text-based online interviews. Twelve students’ attributes on ICT material possession and competencies and experience of Open Distance and Open Learning (ODeL) were collected and analysed. The findings show that the majority of students (72%) who had prior knowledge about the basic concepts of ODeL modalities indicated satisfaction with the e-learning environment while the learning mode is challenging for traditional students (28%). Statistically significant positive correlations (ρ = 0.00) were observed between ICT competencies or preparedness: the level of prior academic qualifications (HAQ: r² = 0.35); key challenge faced (KC: r² = 0.26); and the convenience of ODeL (C.ODeL: r² = 0.18). To ensure that students are not left behind with the proliferation of ICT in distance education, principal component analysis revealed that having prior knowledge about the ODeL modalities is an important attribute that contributes to students’ preparedness for the e-learning environment, thus bridging the variance between the expected expectations and the actual expectations.

The notion of using fracture mechanics in reliability assessment is to make sure that the materials used in manufacturing critical components can survive the intended conditions. Fracture mechanics calculate the energy of a crack using the stress intensity factor (SIF). The SIF is a function of the applied (repeated) load and the orientation of the crack; it determines the extent and form of the plastic component ahead of the crack's tip. In damage tolerance analysis an assumption is made that fatigue cracks can begin to grow in a component during its functioning life and that evolution of these minor cracks in fatigue will happen with continued applied stress. Determining the initiation of the cracks and the evolution can help assess a component's reliability. In metals, corrosion pits have been identified as the stress concentrators providing surroundings favorable for crack initiation and propagation. In this work, a Finite Element Analysis (FEA) is applied to study the SIF around a corrosion pit under axial tension loading. The determined SIF has been used in an analytical reliability-based method using first passage probability theory to determine the reliability of corroded cast iron pipes (as an example).

A novel reliability evaluation methodology of complex systems is proposed using dynamic object-oriented Bayesian networks (DOOBNs). This modeling methodology consists of two main phases, namely, construction phases for object-oriented Bayesian networks (OOBNs) and for DOOBNs. In the first phase, the network fragments with similar structures and parameters are divided into classes; these classes are then encapsulated. The construction of OOBNs is completed according to the relationship among the encapsulated classes. In the second phase, every fragment of the dynamic Bayesian networks that was constructed by the first phase is encapsulated as a class called DOOBN. The construction of DOOBNs is completed according to the relationship among the time fragments. The accuracy of this methodology is validated using the all-series, all-voting, voting-after-series, series-after-voting, parallel-after-series, and series-after-parallel systems. This methodology is further illustrated and verified by using deepwater blowout preventer system and can model the system from global to local levels, thereby effectively reducing modeling difficulty and adopting efficient arithmetic reasoning algorithms.

Glass materials possess properties that are highly needed in various areas of today's and future innovation applications. In this study, we concentrated on optimization of Ultrasonic Assisted Vibration Grinding parameters for Ultra-Low Expansion (ULE) optical glass using the Taguchi method. This material is of interest as it finds its applications in the space industry such as Hubble telescope. A hybrid process of grinding; Ultrasonic Assisted Vibration Grinding (UAVG) has been used in this work, an alternative to solving the current problems with machining glass materials. We investigated the effects of control parameters; Feedrate, Depth of cut, Spindle speed, and Diamond grit size, on response variables; surface roughness and cutting force. Using Signal to Noise ratios (S/N) and Analysis of Variance (ANOVA), the machining parameters were optimized revealing that for Surface roughness had was more influenced by the spindle speed while diamond grit size influenced the cutting force.

This paper describes an improved error separation technique (EST) for on-machine surface profile measurement which can be applied to optical lenses on precision and ultra-precision machine tools. With only one precise probe and a linear stage, improved EST not only reduces measurement costs, but also shortens the sampling interval, which implies that this method can be used to measure the profile of small-bore lenses. The improved EST with stitching method can be applied to measure the profile of high-height lenses as well. Since the improvement is simple, most of the traditional EST can be modified by this method. The theoretical analysis and experimental results in this paper show that the improved EST eliminates the slide error successfully and generates an accurate lens profile.