Science led vs design led teaching approaches in materials science and engineering for aeronautical engineering students

A comparison on teaching styles has been conducted by analysing behavioural, cognitive, developmental, social cognitive and constructivist perspectives of 26 students (higher engineering apprentices). All of those students are in their full-time employment at Broughton factory (Airbus UK) and were comprehensively surveyed at the end of module (ENGF405: Composites and Aeronautical Materials) to quantify their learning experiences. It is generally assumed that design led, in comparison to science led, approach is the most appropriate method for these hands-on engineering professionals. However, presented results are quite interesting because majority of the high achievers have opted for science led approach for their improved learning experiences during the module

Epoxy – the hub for the most versatile polymer with exceptional combination of superlative features

Epoxy resins and epoxy based materials have experienced significant advancement since their beginning in 1936, when Dr. Castan of Switzerland and Dr. Greenlee of USA succeeded in synthesizing the very first bisphenol-A-based epoxy resins. Whether it is the new carbon fiber composite of Boeing’s Dreamliner or the thin set terrazzo flooring, epoxy has always been the ideal choice because of its superlative properties and unique chemical composition. Belonging to thermoset family, it is certainly one of the most versatile polymers we see around in composites, aerospace, automotive, marine, sports materials, construction, structures, electrical and electronic systems, biomedical devices, thermal management systems, adhesives, paints and coatings, industrial tooling and other general consumer products. Because of its versatile nature, epoxy is replacing many conventional materials, e.g. epoxy based materials have already replaced wood in majority of the boats and various sports goods. Epoxy is an open-access journal and offers a fast and comprehensive peer-review. To ensure that the journal has the largest possible impact in this early phase, no publication fees will apply until the end of 2015

Developer-Planner Interaction in Transportation and Land Use Sustainability, MTI Report 01-21

This study argues that significant unmet demand exists for alternatives to conventional auto-oriented development; and further that planning interventions that restrict densities and land use mixing in developed areas are a major reason that this demand remains unmet. In order to explore these hypotheses, this study carried out two principal investigations. The first is a national survey of developers, randomly selected from the database of the Urban Land Institute in Washington, DC, the premiere national organization of land developers. Overall, the survey reveals considerable interest on the part of the private development community in developing in a fashion that is more compact than regulations currently allow. This interest varied by region, with the greatest interest expressed in the densely settled regions of the mid-Atlantic and the Northeast. Developers in the Southwest and South Central regions (Texas, New Mexico, Oklahoma, Arkansas and Louisiana) expressed considerably less interest in developing in a more dense or mixed-use fashion than permitted by current regulation. Similarly, interest in developing more intensely than current regulations permit varied by setting. Little such interest exists for development in rural areas, but developers\u27 interest in such development in inner suburbs was especially keen

Re-agglomeration of carbon nanotubes in two-part epoxy system; influence of the concentration

Carbon nanotubes, because of their exceptional mechanical properties, are one of the potential reinforcements for polymers in near future. Before substituting these nanocomposites in commercial applications, there are many problems, like dispersion, agglomeration, cost effectiveness etc., which need to be sorted. Processing such nanocomposites for longer durations is quite frequently observed these days. Apart from the other major obstacles, re-agglomeration, because of strong van der walls forces between carbon nanotubes, is one of the latest problems that has been always underestimated and ignored. In this study, different carbon nanotubes (Single-wall nanotubes (SWNT), Double wall nanotubes (DWNT), Amino-modified double wall nanotubes (DWNT-NH2), Thin Multi wall nanotubes (MWNT) and COOH-modified thin multi wall nanotubes (MWNT-COOH)) at different concentrations (0.025, 0.05 and 0.1 %wt) in two-part epoxy system (Liquid Epoxy, Liquid hardener and Liquid epoxy-hardener mixture) were studied involving nano-particle size analyzer. After a study of 3 hours, it was observed that there is a strong dependence of re-aggregation profile on the employed homogenizing technique, i.e. high-power bath ultrasonication in this study. Apart from nanotubes/epoxy mixture, higher concentrations yielded higher aggregates profile and vice versa. Re-agglomeration, with the passage of time, in liquid epoxy was found to be least as compared to liquid hardener and liquid epoxy-hardener mixture. Hardener in liquid-epoxy mixture was the main culprit responsible for re-aggregation. Results were further verified by scanning electron microscopy, which revealed significant differences in the microstructures of the cured and fractured samples. Suggestions for altering processing parameters in order to avoid this major obstacle are discussed

Vibration and buckling of cross-ply composite beams using refined shear deformation theory

Vibration and buckling analysis of cross-ply composite beams using refined shear deformation theory is presented. The theory accounts for the parabolical variation of shear strains through the depth of beam. Three governing equations of motion are derived from the Hamilton’s principle. The resulting coupling is referred to as triply coupled vibration and buckling. A two-noded C1 beam element with five degree-of-freedom per node is developed to solve the problem. Numerical results are obtained for composite beams to investigate modulus ratio on the natural frequencies, critical buckling loads and load-frequency interaction curves

Carbon nanotubes for epoxy Nanocomposites: a review on recent developments

Carbon nanotubes (CNTs) are one of the strongest and stiffest engineering fibres. Due to their unique combination of chemical and physical properties at an incredibly small size, they possess great potential to be used as nanofillers for many structural and functional materials, particularly in aerospace sector. Depending on the type, geometrical parameters, concentration, dispersion and many other factors, CNTs can significantly modify the mechanical, electrical and thermal properties of epoxy based materials. This review paper, covering methods of synthesis, composite processing techniques and properties, presents an overview of develop-ments in the field of CNT/ epoxy nanocomposites in recent years

A Short Note on the Bruinier-Kohnen Sign Equidistribution Conjecture and Hal\'asz' Theorem

In this note, we improve earlier results towards the Bruinier-Kohnen sign equidistribution conjecture for half-integral weight modular eigenforms in terms of natural density by using a consequence of Hal\'asz' Theorem. Moreover, applying a result of Serre we remove all unproved assumptions.Comment: 4 pages, main result made unconditional, minor changes due to referee's report

Challenges of Hydraulic Fracturing in Low Permeability Reservoirs

Hydraulic fracturing treatment is applied to the low permeability reservoirs to improve the permeability and resultantly productivity. It has been observed in some cases that fracture stimulated wells produces less than before treatment. The present study is to identify key challenges faced in the hydraulic fracturing treatment are fracture containment and fracture conductivity. Fracture containment is, to control the height growth of the fracture upward and downward. Failure to implement fracture containment might break into an overlain gas cap or water zone underneath. While fracture conductivity is proportional to the well productivity i.e. more conductive the fracture is the more productive it is. Failing to achieve required conductivity will result in reduced productivity. The present study also analysed reported techniques which were successful to control these problems. Field examples are discussed illustrating techniques applied to contain the fracture within the pay zone and improve fracture conductivity

Effects of impurities on particle sizing by acoustic attenuation spectroscopy

It is important to have correct information regarding particle size in order to interpret, control, and optimize many industrial processes. Prior to the recent advent of acoustic attenuation spectroscopy, it was difficult to study particle size distribution online and under real process conditions in processes involving concentrated dispersions (suspensions or emulsions). The technique still needs improvement because it is less known how and under which conditions to employ the technique when dispersions involve impurities that could be soluble, insoluble, in the form of additives, and so on. This lack of understanding has almost halted the advancement in applications of the technique to various processes that essentially involve dispersions with impurities. This study investigates aqueous suspensions of CaCO3 at different concentrations (i.e., 5%, 10% and 20% mass/mass) with added impurities of MgCO3 (insoluble impurity), NaNO3 (soluble impurity) and sodium polyacrylate (soluble additive) at varying proportions (5%, 10%, 20% and 30% of the weight of CaCO3). The study characterizes and compares dispersion with and without impurity in order to demonstrate the possible ways in which addition of an impurity change the original acoustic attenuation spectrum of a dispersion. The study brings the conditions in which acoustic attenuation spectroscopy is capable of explaining that addition of an impurity will not change original particle size of the disperse medium