Developing a national quality culture for further and higher education in a micro-state : the case of Malta

In July 2015 Malta inaugurated its National QA Framework for Further and Higher Education to foster a comprehensive quality culture in the sector. This is the first QA framework within the European Higher Education Area (EHEA) that covers further, higher and adult formal educational provision. It is also significant because it presents an alternative to the neo-liberal New Public Management paradigm of QA in higher education that is dominant internationally. Indeed, the Framework is based on the 2015 version of the European Standards and Guidelines (ESG) which focus on quality enhancement rather than accountability, enriched with elements from the EU system of QA for vocational education (EQAVET). The rhetorical positioning of the Framework as well as its overarching nature were possible because of Malta’s characteristics as a former colony and as a micro-state. This paper discusses how Malta’s characteristics informed the development of Malta’s QA Framework, and how the Framework itself was developed and implemented.epeer-reviewe

Microscopic investigation of soot and ash particulate matter derived from biofuel and diesel: implications for the reactivity of soot

Investigation of soot and ash particulate matter deposited in diesel particulate filters (DPFs) operating with biofuel (B100) and diesel (pure diesel: B0 and diesel80/biofuel20 blend: B20) by means of optical microscopy, scanning electron microscopy, and high resolution transmission electron microscopy (HRTEM) reveals the following: the rapeseed methyl ester biofuel used for this study contributes to ash production, mainly of Ca-S- and P-bearing compounds ranging in size between 50 and 300nm. Smaller ash particles are less common and build aggregates. Ash is deposited on the inlet DPF surface, the inlet channel walls, and in B100-DPF at the plugged ends of inlet channels. The presence of Fe-Cr-Ni fragments, down to tens of nanometers in size within the ash is attributed to engine wear. Pt particles (50-400nm large) within the ash indicate that the diesel oxidation catalyst (DOC) upstream of the DPF shows aging effects. Radial cracks on the coating layer of the DOC confirm this assumption. The B100-DPF contains significantly less soot than B20 and B0. Based on the generally accepted view that soot reactivity correlates with the nanostructure of its primary particles, the length and curvature of graphene sheets from biofuel- and diesel-derived soot were measured and computed on the basis of HRTEM images. The results show that biofuel-derived soot can be more easily oxidized than diesel soot, not only during early formation but also during and after considerable particle growth. Differences in the graphene sheet separation distance, degree of crystalline order and size of primary soot particles between the two fuel types are in line with this inferenc

Single-phase microgrid with seamless transition capabilities between modes of operation

Microgrids are an effective way to increase the penetration of DG into the grid. They are capable of operating either in grid-connected or in islanded mode thereby increasing the supply reliability for the end user. This paper focuses on achieving seamless transitions from islanded to grid-connected and vice versa for a single phase microgrid made up from voltage controlled voltage source inverters (VC-VSIs) and current controlled voltage source inverters (CC-VSIs) working together in both modes of operation. The primary control structures for the VC-VSIs and CC-VSIs is considered together with the secondary control loops that are used to synchronize the microgrid as a single unit to the grid. Simulation results are given that show the seamless transitions between the two modes without any disconnection times for the CC-VSIs and VC-VSIs connected to the microgrid.peer-reviewe

Reactive power sharing and voltage harmonic distortion compensation of droop controlled single phase islanded microgrids

When paralleling multiple inverters that are capable of operating as an island, the inverters typically employ the droop control scheme. Traditional droop control enables the decentralized regulation of the local voltage and frequency of the microgrid by the inverters. The droop method also enables the inverters to share the real and reactive power required by the loads. This paper focuses on some of the limitations of parallel islanded single phase inverters using droop control. Algorithms with the aim to address the following limitations in islanded operation were proposed: reactive power sharing and reduction of the voltage harmonic distortion at the point of common coupling (PCC). Experimental results were then presented to show the suitability of the proposed algorithms in achieving reactive power sharing and in improving the voltage harmonic distortion at the PCC.peer-reviewe

Utility-scale storage integration in the Maltese medium-voltage distribution network

Deployment of renewable energy sources in Malta is limited by grid integration constraints. Photovoltaic (PV) systems pose a significant risk to grid stability due to their inherent intermittency and result in overvoltages at the medium-voltage and low-voltage networks. Investments in utility-scale battery energy storage systems (BESS) will facilitate further deployment of renewables and will help to achieve energy security. This study proposed a novel sizing strategy for utility-scale battery energy storage systems (BESS) based only on technical considerations to find the minimum required storage capacity based on historical electricity demand and PV generation. The modeling and simulation were constrained to a section of the Gozitan 11 kV electrical distribution network and the results showed that the utility-scale storage can reduce the impact of PV systems on the grid infrastructure by avoiding reverse power flows and improve the local energy security by reducing the peak electricity demand. The central BESS and the decentralized coordinated BESS with “equal sizing” stored 3.4 MWh while the decentralized coordinated BESSs with “optimal sizing” stored 5.307 MWh. In all three cases, the evening peak demand was reduced by 30.5% from 2.62 MW down to a defined limit of 1.82 MW. From the results presented in this paper, the “optimal sizing” strategy showed that the BESSs have most benefit when installed next to the local PV generation. Hence, by deploying coordinated utility-scale BESSs sized according to the PV generation potential, it is expected that the penetrations of PV generation can be increased even with the present distribution network infrastructure.peer-reviewe

Aortic coarctation : never too late to diagnose, never too late to treat

We present two cases of severe aortic coarctation detected in adulthood and who underwent successful relief by transcatheter stent deployment using a new covered stent, Optimus® stent (AndraTec GmbH Koblenz, Germany). One patient is a 46-year old female with resistant arterial hypertension, in whom coarctation was suspected on a follow-up transthoracic echocardiogram for bicuspid aortic valve disease and subsequently confirmed on magnetic resonance imaging. The second patient is a 68-year old male whose coarctation was diagnosed incidentally at coronary angiography being performed as part of the preoperative work-up for severe aortic stenosis. Suprasternal views to assess aortic arch and flows in the proximal descending aorta should be a standard part of every transthoracic echocardiogram. Treatment of aortic coarctation should be considered irrespective of patient’s age.peer-reviewe

Modeling of an EMC test-bench for conducted emissions in solid state applications

In the area of EMC performance of electric motor drives, research is mainly focused on the EMC performance of inverter based drives. However, in most instances the soft starter is still an appropriate choice for motor control especially when accurate speed control of the load is not a specific requirement. The EMI generation of these converters has not been given the required importance, with only a few publications regarding this issue available in the last decades. A simulation model that considers the operation of solid state devices in an EMC conducted emission measurement laboratory environment was developed. The model was implemented in MATLAB® and Simulink® using a time domain approach. Models for the LISN, EMI receiver, power cables, thyristor power modules and induction motor load were developed and implemented. These models were developed so as to reflect the actual physics of the components and, where possible, model parameters were obtained through analysis of the geometry of the system through simplifications of the surrounding environment. The simulation was then used to gain insight on the EMI generation mechanisms of the solid state system.non peer-reviewe