Today
Bookmark and Share    
Full Text
Peer Reviewed
See detailFeasibility of Stellar as a Blockchain-based Micropayment System
Khan, Nida UL; Ahmad, Tabrez; State, Radu UL

in Springer SmartBlock 2019 - 2nd International Conference on Smart Blockchain (in press)

The advent of Bitcoin was heralded as an innovation in the global monetary system, that could bring down transaction fees by circumventing the need for third parties and conduct transactions in real time ... [more ▼]

The advent of Bitcoin was heralded as an innovation in the global monetary system, that could bring down transaction fees by circumventing the need for third parties and conduct transactions in real time. The divisibility of a blockchain cryptocurrency to even fractions of a cent, caused microtransactions to become feasible to formerly non-existent denominations. These microtransactions have spurred the development of novel ways of monetizing online resources and hold the potential to aid in alleviation of poverty. The paper conducts a feasibility study on Stellar as a blockchain-based micropayment system. It highlights the computational and other issues that impedes its progress and utilizes a characterization model for micropayment systems to evaluate the efficacy of the Stellar platform. The paper conducts a comparison with the micropayment solutions from Bitcoin, Ethereum and PayPal. The paper analyzes a subset of transactions from the Stellar blockchain to aid in drawing a conclusion on the undertaken study and elaborates on the mitigation tools to enable fraud prevention in online monetary transactions. [less ▲]

Detailed reference viewed: 38 (8 UL)
Full Text
See detailOn Recent Activities at GNSS@TG Stations in the South Atlantic Ocean and the Tracking of Hurricanes Using GNSS
Teferle, Felix Norman UL

Presentation (2019, August 07)

Guest lecture to third year students in Geomatics and Geoinformation at the University of Cape Town. The topics covered the geodetic activities in the South Atlantic Ocean and the tracking of hurricanes ... [more ▼]

Guest lecture to third year students in Geomatics and Geoinformation at the University of Cape Town. The topics covered the geodetic activities in the South Atlantic Ocean and the tracking of hurricanes both involving GNSS. The contents were recently presented orally at IUGG 2019 and ISAES 2019. [less ▲]

Detailed reference viewed: 36 (1 UL)
Full Text
See detailStudy of nanopulsed discharges for plasma-polymerization: experimental characterization and theoretical understanding of growth mechanisms in the deposition of functional polymer thin films
Loyer, François UL

Doctoral thesis (2019)

Plasma processes are highly versatile methods able to promote the formation of thin films from a vast variety of compounds thanks to the numerous energetic species they generate. Notably, plasma-enhanced ... [more ▼]

Plasma processes are highly versatile methods able to promote the formation of thin films from a vast variety of compounds thanks to the numerous energetic species they generate. Notably, plasma-enhanced chemical vapor deposition (PECVD) processes have already led to the simultaneous synthesis and deposition of a wide variety of organic functional materials. Reciprocally, the many reactive species composing the plasma induce a non-negligible number of side reactions, yielding altered chemistry compared to conventional polymerization processes. Therefore, there is a strong need for controlled methods promoting conventional polymerization pathway in plasma-based processes to increase their range of application. To this end, the atmospheric-pressure plasma-initiated chemical vapor deposition (AP-PiCVD) process was developed, differing from classical PECVD by its initiation source. AP-PiCVD relies on square-wave nanopulsed discharges with single ultra-short plasma on times (t_on ≈ 100 ns) and long plasma off-times (t_off = 0.1 – 100 ms) rather than alternative current sources yielding long and repeated discharges (t_on = 10 µs). Methacrylate monomers initiated by nanopulsed discharges highlighted a shift of growth mechanisms from classical PECVD pathways (plasma-polymerization) to conventional free-radical polymerization. Notably, the growth of polymer layers with an extremely high retention of the monomer’s chemistry and unprecedented molecular weights for an atmospheric-pressure plasma process is demonstrated at long plasma off-times. Moreover, a transition from gas phase to surface growth mechanisms is observed, allowing the deposition of conformal coatings similarly to low-pressure alternative chemical vapor deposition processes. A thorough investigation of the thin films’ chemistry confirms the conventional nature of the layers grown by AP-PiCVD and shed light upon the growth mechanisms in low-frequency nanosecond pulsed plasmas. While the on-time induces the formation of free radicals from the monomers’ fragmentation which are able to initiate and terminate the chain addition process, conventional polymerization mechanisms are strongly promoted during the off-time yielding linear polymer core. Interestingly, new insights on selective initiation mechanisms based on sacrificial functions for an enhanced control of the molecular fragmentation are put forward and discussed. The development of a model describing the kinetic of pulsed plasma was carried out and correlated with experimental observations, providing deeper understanding of the interaction between the gas phase and the surface. The extraction of important physical parameters for the description of the growth kinetics in AP-PiCVD is demonstrated and their significance discussed. Using the fundamental knowledge developed on nanosecond pulsed plasma-initiated polymerization mechanisms, thermoresponsive copolymer layers grown by AP-PiCVD are reported for the first time. The properties of the layers are evaluated and related to their chemistry, allowing the determination of an optimal co-monomers ratio to integrate both of their individual properties as a unique functional thin film. [less ▲]

Detailed reference viewed: 37 (3 UL)
Full Text
Peer Reviewed
See detailRatings, Rankings, Research Evaluation: How do Schools of Education Behave Strategically within Stratified UK Higher Education?
Marques, Marcelo UL; Powell, Justin J W UL

in Higher Education (2019)

While higher education research has paid considerable attention to the impact of both ratings and rankings on universities, less attention has been devoted to how university subunits, such as Schools of ... [more ▼]

While higher education research has paid considerable attention to the impact of both ratings and rankings on universities, less attention has been devoted to how university subunits, such as Schools of Education, are affected by such performance measurements. Anchored in a new institutional approach, we analyze the formation of a competitive institutional environment in UK higher education in which ratings and rankings assume a central position in promoting competition among Schools of Education (SoE). We apply the concepts of “ institutional environment” and “ organizational strategic actors” to UK SoE to demonstrate how such university subunits articulate their qualities and respond to the institutional environment in which they are embedded—by using ratings and rankings (R&R) to compete for material and symbolical resources as well as inter-organizational and intra-organizational legitimacy. Through findings from 22 in-depth expert interviews with members ofthe multidisciplinary field of education and a content analysis of websites (n = 75) of SoE that participated in REF 2014, we examine the stratified environment in which SoE are embedded (1). We uncover how R&R are applied by SoE within this competitive, marketized higher education system (2). Finally, we indicate the strategic behaviors that have been triggered by the rise of R&R in a country with a highly formalized and standardized research evaluation system (3). The results show both homogenization and differentiation among SoE in their use of organizational vocabulary and the applications of R&R while simultaneously revealing strategic behavior, ranging from changes in internal practices to changes in organizational structures. [less ▲]

Detailed reference viewed: 44 (3 UL)
Full Text
See detailThe 15 puzzle
Perucca, Antonella UL

E-print/Working paper (n.d.)

Detailed reference viewed: 38 (1 UL)