Changing evaluation of a master programme module to improve students' overall achievements

One of the modules delivered since 2001 in the Mechanical Engineering taught Masters Programme at Dublin City University is entitled “Product Design, Development and Value Analysis”. The module is assessed by two continuous assessments, both worth 10% and by a final exam worth 80%. In 2005, the exam period of this module was increased from 120 minutes to 150 minutes. Additionally, the second continuous assessment assignment was change from a report assignment to a set of 20 Multiple Choice Questions (MCQ) covering the entire module content. This assessment was run in the final week of the module. The first assignment was and remains as a report assignment. These two modifications were introduced to give the students sufficient time to complete the exam paper, and to provide a more comprehensive evaluation by the students for themselves as to their extent of knowledge on the module content. Average results of continuous assessment, exam marks, and overall marks before and after the change were assessed from 2002 to 2015 and presented in this paper. The two above-mentioned changes brought 14.2% increase in the continuous assessment average results, and 15.7% increase in the final exam marks. Therefore the combined effect of the changes has resulted in a significant positive increase in the student overall achievement within this module. The data and reasons behind these changes are discussed

Nitrogen doping in biomaterials by extreme ultraviolet (EUV) surface modification for biocompatibility control

Various studies show that employment of nitrogen coatings on certain biomaterials can noticeably increase the degree of biocompatibility (particularly for vascular repair) [1]. Chemical and laser ablation surface modification techniques are used for introduction or enrichment of nitrogen. However alteration of bulk material is reported which is undesirable for biomedical engineering applications. Extreme Ultraviolet (EUV) radiation with low penetration depth (less than 100 nm) can be successfully utilized to avoid bulk properties alteration. In this study Polyvinyl fluoride (PVF) and Polytetrafluoroethylene (PTFE) were treated by EUV radiation in the presence of ionized nitrogen. X-ray photoelectron spectroscopy (XPS) measurements demonstrate a notable amount of nitrogen on treated polymer surfaces

MXene materials based printed flexible devices for healthcare, biomedical and energy storage applications

The advent of cost effective printed smart devices has revolutionized the healthcare sector by allowing disease prediction and timely treatment through non-invasive real time and continuous health monitoring. Future advancements in printed electronic (PE) materials will continue to enhance the quality of human living. For any PE application, materials should possess proper mechanical integrity and resistivity while being non-toxic. In the case of sensing devices for physiological and biochemical signals, excellent conductivity is an essential requirement for obtaining high response signals. The emergence of the novel class of 2D materials called MXenes and their composites has resulted in structures and materials hugely relevant for healthcare devices. Exploiting solution based 2D MXene materials can expedite their practical application in PE devices by overcoming the present limitations of conductive inks such as poor conductivity and the high cost of alternative functional inks. There has been much progress in the MXene functional ink generation and its PE device applications since its discovery in 2011. This review summarizes the MXene ink formulation for additive patterning and the development of PE devices enabled by them in healthcare, biomedical and related power provision applications

Laser welding of polypropylene using two different sources

In this paper, laser weldability of neutral polypropylene has been investigated using fibre and carbon dioxide lasers. A design of experiment (DoE) was conducted in order to establish the influence of the main working parameters on the welding strength of the two types of laser. The welded samples were characterized by carrying out visual and microscopic inspection for the welding morphology and cross-section, and by distinguishing the tensile strength. The resulting weld quality was investigated by means of optical microscopy at weld cross-sections. The tensile strength of butt-welded materials was measured and compared to that of a corresponding bulk material

Surface structuring and wettability control of Polyvinyl fluoride (PVF) using extreme ultraviolet (EUV) surface modification.

In this study, surface modification of fluoropolymer Polyvinyl fluoride (PVF) films was performed using Extreme Ultraviolet (EUV) radiations to induce patterned structures on surface and to provide control over the surface wettability. Specially developed laser produced plasma based EUV source was used for surface structuring. The double stream gas-puff target was produced by injection of krypton and xenon (KrXe) gas mixture into a hollow stream of helium. Commercially available EKSPLA Nd:YAG 1.06 micron laser was used to irradiate the KrXe gas puff target with 3 nanosecond pulse duration having 0.8 J energy. The PVF films were irradiated with 50 and 200 EUV pulses. The surface characterisation of the pristine and EUV modified PVF polymer films was performed by Atomic Force Microscopy (AFM) for morphological modifications. To investigate chemical modifications, X-ray Photoelectron Spectroscopy was used. The wettability of the sample surfaces was examined by Water Contact Angle (W CA) measurements. EUV surface modification of PVF films resulted in formation of wall type rippled structures on the polymer surfaces. The surface roughness of the EUV treated surfaces was increased up to 287 nm and 21° reduction was observed in the WCA of the PVF films. Successful surface structuring and wettability control was obtained using EUV surface modification of PVF films

Advanced production routes for metal matrix composites

The use of metal matrix composites (MMCs) in a variety of products is significantly increasing with time due to the fact that their properties can be tailored and designed to suit specific applications. However, the future usage of MMC products is very much dependent on their beneficial aspects and hence it is critical to ensure in a robust repeatable manner the superior physical property advantages compared to conventional unreinforced monolithic metal counterparts. Although numerous routes are available for production of MMC products, each of them has their own advantages and disadvantages. This article provides an overview of advanced production routes for MMCs. The discussion also highlights challenges and presents a future prospectus for MMCs. Powder metallurgy and casting routes are still extensively used for production of MMCs. Aluminum alloys are today the most commonly used matrix materials in MMC products. Carbides (eg, SiC, TiC, and B4C), carbon allotropes (eg, CNTs and graphene), and alumina (Al2O3) are currently the most used reinforcement materials. Nevertheless, the use of nano and of hybrid reinforcements are seeing increased usage in niche applications. Additive manufacturing (AM) is discussed as a novel production route for MMC products. This process represents a promising method for the production of MMC products

Polycarbonate polymer surface modication by extreme ultraviolet (EUV) radiation

The degree of the biocompatibility of polycarbonate (PC) polymer used as biomaterial can be controlled by surface modification for various biomedical engineering applications. In the past, PC samples were treated by excimer laser for surface reorganization however associated process alteration of bulk properties is reported. Extreme ultraviolet radiation can be employed in order to avoid bulk material alteration due to its limited penetration. In this study, a 10 Hz laser-plasma EUV source based on a double-stream gas-pu_ target irradiated with a 3 ns and 0.8 J Nd:YAG laser pulse was used to irradiate PC samples. The PC samples were irradiated with different number of EUV shots. Pristine and EUV treated samples were investigated by scanning electron microscopy and atomic force microscopy for detailed morphological characterization of micropatterns introduced by the EUV irradiation. Associated chemical modifications were investigated by X-ray photoelectron spectroscopy. Pronounced wall-type micro- and nanostructures appeared on the EUV modified surface resulting in a change of surface roughness and wettability

Assessment of thermo-hydraulic performance of inward dimpled tubes with variation in angular orientations

This paper presents a numerical investigation and assessment of thermal and hydraulic performance of dimpled tubes of varying topologies at constant heat flux of and Reynolds numbers ranging from 2300 to 15,000 The performance of the tubes consisting of conical, spherical and ellipsoidal dimples with equivalent flow volumes were compared using steady state Reynolds Averaged Navier Stokes simulations. The ellipsoidal dimples, in comparison to other dimple shapes, demonstrated large increment in heat transfer rate. The variation in the orientation of the ellipsoidal dimples was examined to further improve thermal and hydraulic performances of the tube. A 45° inclination angle of ellipsoidal dimple, from its major axis, increased the thermo-hydraulic performance by 58.1% and 20.2% in comparison to smooth tube and 0° ellipsoidal dimpled tube, respectively. Furthermore, Large Eddy Simulations (LES) were carried out to investigate the role geometrical assistance to fluid flow and heat transfer enhancement for the 45° and 90° ellipsoidal dimpled tubes. LES results revealed a flow channel of connected zones of wakes which maximized fluid-surface

Investigating the morphology, hardness, and porosity of copper filters produced via Hydraulic Pressing

This paper presents an examination of the production of copper air filters via the Hydraulic Pressing (HP) method. Processing conditions examined included powder particle type (spherical and dendritic), varying compaction pressures (635, 714, and 793 MPa) and different pore forming (polyvinyl alcohol (PVA)) concentrations (1, 2, and 3 wt.%). Following compaction, the samples were thermally sintered in a two stage sintering regime at 200 ◦C and 750 ◦C. The morphology, porosity, and mechanical properties of the sintered samples were characterised. Morphological analysis demonstrated better consolidation and over-lapping of the copper powder particles in samples with a higher weight percentage of the PVA. Highest porosity was achieved in the sample produced using the dendritic copper powder mixed with highest weight percentage of PVA. As the samples were very porous, the hardness of the samples varied greatly. Samples prepared with spherical powders at high pressure demonstrated the highest hardness. The results in this study show that copper filters with 14%e26% porosity can effectively be produced using spherical and dendritic copper powders by controlling the compaction pressure and PVA concentration

Laser surface polishing of Ti-6Al-4V parts manufactured by laser powder bed fusion

Poor surface quality of Additively Manufactured (AM) components, can greatly increase the overall cost and lead time of high-performance components. Examples are medical devices where surfaces may contact the patient’s skin and hence need to be smooth and aerospace components with high fatigue strength requirements where surface roughness could reduce fatigue life. The average surface roughness (Ra) of AM parts can reach high levels greater than 50 microns and maximum distance between the high peaks and the low valleys of more than 300 microns. As such, there is a need for fast, cost effective and selective finishing methods of AM produced components targeted at high-performance industries. In this paper Ti-6Al-4V Grade 23 ELI, popular for medical devices and aerospace parts production, was L-PBF processed to manufacture parts which were subsequently treated via laser polishing. Here in this work, CO2 laser polishing was used for the surface modification of the Ti-6Al-4V produced samples. The most significant processing parameters were optimised to achieve approximately an 80% reduction in the average surface roughness and a 90% reduction in the peak-to-valley distance with a processing time of 0.1 sec/mm2 and cost of 0.2 €/cm2