Variable frequency microwave (VFM) processing facilities and application in processing thermoplastic matrix composites

[Abstract]: Microwave processing of materials is a relatively new technology advancement alternative that provides new approaches for enhancing material properties as well as economic advantages through energy savings and accelerated product development. Factors that hinder the use of microwaves in materials processing are declining, so that prospect for the development of this technology seem to be very promising [1]. The two mechanisms of orientation polarisation and interfacial space charge polarisation, together with dc. conductivity, form the basis of high frequency heating. Clearly, advantages in utilising microwave technologies for processing materials include penetration radiation, controlled electric field distribution and selective and volumetric heating. However, the most commonly used facilities for microwave processing materials are of fixed frequency, eg 2.45 GHz. This paper presents a state-of-the-art review of microwave technologies, processing methods and industrial applications, using Variable Frequency Microwave VFM) facilities. This is a new alternative for microwave processin

Applications of fixed and variable frequency microwave (VFM) facilities in polymeric materials processing and joining

Microwave processing of materials is a relatively new technology advancement alternative that provides new approaches for enhancing material properties as well as economic advantages through energy savings and accelerated product development. Factors that hinder the use of microwaves in materials processing are declining, so that prospect for the development of this technology seem to be very promising [Ceram. Bull. 68 (2) (1989) 376]. The two mechanisms of orientation polarisation and interfacial space charge polarisation, together with DC conductivity, form the basis of high frequency heating. Clearly, advantages in utilising microwave technologies for processing materials include penetrating radiation, controlled electric field distribution and selective and volumetric heating. However, the most commonly used facilities for microwave processing materials are of fixed frequency, e.g. 2.45 GHz. This paper presents a state-of-the-art review of microwave technologies, processing methods and industrial applications, using variable frequency microwave (VFM) facilities. This is a new alternative for microwave processing. The technique is geared towards advanced materials processing and chemical synthesis. It offers rapid, uniform and selective heating over a large volume at a high energy coupling efficiency. This is accomplished using a preselected bandwidth sweeping around a central frequency employing frequency agile sources such as travelling wave tubes as the microwave power amplifier. Selective heating of complex samples and industrial scale-up are now viable. During VFM processing, a given frequency of microwaves would only be launched for less than 1 ms

Interactive capstone portfolios

Portfolios are a collection of student work over a period of time. Capstone project portfolios incorporate many forms of written artefacts, e-pages, oral presentations, journals and audio-visual material. Interactive capstone portfolios involve actions by both educators and students to establish a dynamic set of usable and tangible skills. These include the development of writing skills from minor project proposals to major reports or dissertations that are an ongoing learning exercise for the student. For the educator, portfolio development is a method of continuously and actively evaluating and commenting on a student's work, culminating in a final major report. This portfolio report may be in traditional format, or may take the form of several artefacts, viz. electronic portfolios, written report, computer program 3D model, paper poster. (WWW) web page and electronic posters, together with oral presentations. These activities develop communication skills for working within an industrial environment. However, for academic purposes stratification of assessment grades is required, by both peer group assessment and independent academic assessment. Examples of ongoing capstone portfolio content will be given showing that which is submitted formally, and that which remains for the students' creativity, learning and self evaluation

A useful-life model for components containing growing defects

Abstract not available

Modelling and analysis of a femoral neck prosthesis

This paper investigates the stresses around the femoral neck of hip replacements when compared with a repair procedure of hips, which include either a complete hip replacement, or the installation of a Dynamic Hip Screw to hold the hip together. Models were developed and analyzed to determine the high stress regions inside the bone which may cause pain or failure. For the Dynamic Hip Screw (DHS) the highest amount of stress on the bone was found to be near the top screw, and the screw supporting the head/neck of the femur. However, for a total hip replacement, the point of highest stress is located on the prosthetic-bone interface on the opposite side of the bone from the ball of the hip. Caution is required when selecting an appropriate hip repair or replacement for different people

Probabilistic modelling of automotive body joints

We investigate the manner in which variability in the quality of spot welds in automotive body joints contributes to variability in joint stiffness. Joint stiffness is defined here as the resistance to rotation of the joint. The aim is to develop a method of investigating problems of this nature using simulation and statistical techniques, and then to quantify the variation for this particular case. The results are validated by ensuring that the accuracy and resolution of the model are appropriate. Here, accuracy is the degree to which the model represents reality and is determined by achieving convergence of results as finer mesh densities are used

Materials joining applications using variable frequency microwave

Abstract not available

Do engineering students perceive that different learning and teaching modes improve their referencing and citation skills?

The present work explores the research question: do capstone engineering students perceive that different learning and teaching modes improve their referencing and citation skills? Two different teaching and learning modes of instruction were implemented for demonstration and training on the use of engineering databases and bibliographic information retrieval resources: i.e. small group and large group. A survey was conducted of students' perception of the mode of instruction in both a large class format and the small-class hands-on environment. Analysis of the survey data yielded an overall positive response from students to the implementation of computerised bibliographic software for both class formats. However, this study found compelling evidence that students highly value the intensive instruction in a small group to assist them in improving their use and understanding of citations in written documentation

Air cured sisal strand reinforced cement sheet

The aim of this project was to investigate the properties of natural fibre reinforced (Sisal) cement sheeting. Sisal strands were chemically treated and incorporated into cement to produce sheeting suitable for housing. Results from mechanical strength tests indicated Sisal reinforced cements was suitable for construction of dwelling walls or roofs

Probabilistic modelling of automotive body joints

We investigate the manner in which variability in the quality of spot welds in automotive body joints contributes to variability in joint stiffness. Joint stiffness is defined here as the resistance to rotation of the joint. The aim is to develop a method of investigating problems of this nature using simulation and statistical techniques, and then to quantify the variation for this particular case. The results are validated by ensuring that the accuracy and resolution of the model are appropriate. Here, accuracy is the degree to which the model represents reality and is determined by achieving convergence of results as finer mesh densities are used