Social and Behavioral Sciences Commons^™

Statistical Analysis Of Overvoltages Due To The Energisation Of A 132 Kv Underground Cable, M Z. Daud, P Ciufo, S Perera

Dr Philip Ciufo

Analysis by means of simulation studies is essential for providing useful information to distribution engineers and researchers regarding high frequency switching transients in cable systems. The behaviour of transients due to switching is strongly dependent on the pole closing span of the circuit breaker and also the closing angle of the power frequency voltage. This behaviour requires the study of overvoltage magnitude distributions to be carried out using a statistical approach. This paper presents an analysis of overvoltage sensitivity due to circuit breaker operations when energising an unloaded 132 kV underground cable system. Based on two approaches, the overvoltage values …

A Review Of Recent Investigations On Voltage Unbalance Management: Further Contributions To Improvement Of Iec/Tr 61000-3-13:2008, Jayatunga Vitharanage Upuli Priyadarshani Jayatunga, Sarath Perera, Philip Ciufo, Ashish Agalgaonkar

Dr Philip Ciufo

Voltage unbalance (VU) management in power systems essentially involves two major aspects: VU emission allocation at the pre-connection stage and compliance assessment at the post-connection stage of installations. This is a summary and a review paper on the recent investigations completed in relation to VU emission assessment techniques which provide further contributions to the improvement of IEC Technical Report IEC/TR61000-3-13:2008. Generalised approaches developed for the classification of different sources of unbalance at the point of evaluation (covering both radial and interconnected networks) and the evaluation of their individual contributions giving emphasis to the discrimination between customer and network responsibility on …

Solar Pv And Battery Storage Integration Using A New Configuration Of A Three-Level Npc Inverter With Advanced Control Strategy, Hamid Teymour Ghasemabadi, Danny Soetanto, Kashem M. Muttaqi, Philip Ciufo

Dr Philip Ciufo

In this paper, a novel configuration of a three-level neutral-point-clamped (NPC) inverter that can integrate solar photovoltaic (PV) with battery storage in a grid-connected system is proposed. The strength of the proposed topology lies in a novel, extended unbalance three-level vector modulation technique that can generate the correct ac voltage under unbalanced dc voltage conditions. This paper presents the design philosophy of the proposed configuration and the theoretical framework of the proposed modulation technique. A new control algorithm for the proposed system is also presented in order to control the power delivery between the solar PV, battery, and grid, which …

Power Quality Emission Assessment Of Photovoltaic Inverters Based On Iec Technical Report 61000-3-15:2011, Devinda Perera, Philip Ciufo, Lasantha G. Meegahapola, Sarath Perera

Dr Philip Ciufo

The International Electrotechnical Committee Technical Report IEC 61000-3-15:2011 provides electromagnetic compatibility requirements and test conditions for distributed generators up to 75 A per phase. In the current research, two commercially available photovoltaic (PV) inverters up to the capacity of 3600 W were tested following the guidelines proposed in IEC 61000-3-15 in relation to low order harmonic emission and flicker emission. In addition, the harmonic and flicker emission behaviour of the PV inverters were investigated under varying irradiation conditions. Both PV inverters were observed to comply with the emission requirements prescribed by the technical report under most conditions except for even …

Fault Approximation Tool For Grid-Connected Inverter-Interfaced Distributed Generators, Joel Kennedy, Philip Ciufo, Ashish Agalgaonkar

Dr Philip Ciufo

A novel fault approximation tool (FAT) is presented for use in distribution networks with a high penetration of inverter-interfaced distributed generation. The FAT does not rely on balanced operation nor an absolute reference point for voltage calculations, both of which are required for Newton-Raphson load flow calculations. Simulations show that the FAT provides an accurate representation of the transient and steady-state fault response for unbalanced faults when juxtaposed with a detailed small-signal model. The `sub-transient' response of the inverter-interfaced distributed generation is omitted to remove data considered extraneous from the perspective of distribution line protection analysis. The FAT is not …

Performance Of Adjustable Speed Drives Subject To Regular Voltage Fluctuations, Kun Zhao, Philip Ciufo, Sarath Perera

Dr Philip Ciufo

The impact of power quality disturbances on customer equipment has been a topic of interest to equipment manufacturers, electricity utilities, customers and to those involved in the development of electromagnetic compatibility standards. Recently, a new interest has developed in the possible impact of voltage fluctuations on customer equipment because of suggestions to relax voltage fluctuation limits and hence the flicker limits in power systems. With a view to contribute to this understanding, this paper investigates the performance of an adjustable speed drive (ASD) when subjected to sinusoidal regular voltage fluctuations. When the ASD is operating in open loop mode, the …

A Sensitivity Analysis Toolkit For The Simplification Of Mv Distribution Network Voltage Management, Fabian Tamp, Philip Ciufo

Dr Philip Ciufo

As distribution networks become increasingly variable and generation becomes increasingly decentralised, voltage standards are becoming more liable to violation. Accordingly, intelligent voltage management strategies are required to enable standards compliance without unduly increasing network maintenance or infrastructure costs. The relationship between network power and voltages, however, is complex, non-linear and interdependent, and thus is difficult to conceptualise and use for decision-making and control purposes. This paper introduces a software toolkit that simplifies the development of voltage management strategies by the application of sensitivity analysis. Sensitivity analysis reduces complex network relationships to simple linear equations, and thus enables easy and comprehensive …

Microgrids Of Commercial Buildings: Strategies To Manage Mode Transfer From Grid Connected To Islanded Mode, Lasantha Meegahapola, Duane A. Robinson, Ashish Agalgaonkar, Sarath Perera, Philip Ciufo

Dr Philip Ciufo

Microgrid systems located within commercial premises are becoming increasingly popular and their dynamic behavior is still uncharted territory in modern power networks. Improved understanding in design and operation is required for the electricity utility and building services design sectors. This paper evaluates the design requirements for a commercial building microgrid system to facilitate seamless mode transition considering an actual commercial building microgrid system. A dynamic simulation model of the proposed microgrid system is established (utilizing DIgSILENT Power Factory) to aid the development of planning and operational philosophy for the practical system. An economic operational criterion is developed for the microgrid …

Balancing Energy In The Smart Grid Using Distributed Value Function (Dvf), Hassan Shirzeh, Fazel Naghdy, Philip Ciufo, Montserrat Ros

Dr Philip Ciufo

As the penetration of renewable energy resources increases in distribution networks, so does the need to manage these resources in an effective manner. Since these resources are installed to displace carbon-based generation and to provide an income stream to the resource owner, it is important that both installation objectives (as a minimum) can be met. With all of these renewable energy resources available, the opportunity also exists to assist with the energy management of this resource-rich distribution network. However, the renewable energy resources do not produce power in a deterministic manner. The available production depends on the time of day …

Voltage Unbalance Emission Assessment In Interconnected Power Systems, Jayatunga Vitharanage Upuli Priyadarshani Jayatunga, Sarath Perera, Philip Ciufo, Ashish Agalgaonkar

Dr Philip Ciufo

The International Electrotechnical Commission (IEC) Technical Report IEC/TR 61000-3-13:2008 considers voltage unbalance (VU) emission assessment as a key aspect of the VU management of power systems. Compliance assessment of unbalanced installations at the post connection stage is essential to ensure that the limits set by the IEC VU emission allocation methodology in the pre-connection stage are met. Although VU is known to be caused by load asymmetries and inherent network asymmetries, locating all VU emission sources is not a straightforward process, especially in a network with interconnections. Such assessment methodologies should ensure that the contributions from various sources of unbalance …

Voltage Unbalance Emission Assessment: Sources Of Contribution And Their Ranking, U Jayatunga, Sarath Perera, P Ciufo, A P. Agalgaonkar

Dr Philip Ciufo

etermining sources of voltage unbalance (VU) and quantifying their individual contributions in an interconnected network is a complex task due to multiple interactions that take place between them. Post-connection VU emission assessment techniques in relation to customer installations are important not only in compliance assessment according to IEC/TR 61000-3- 13:2008 Limits - Assessment of emission limits for the connection of unbalanced installations to MV, HV and EHV power systems, but also in determining the various emission contributors in the power system being considered. This paper presents a case study on the application of a recently developed post-connection VU emission assessment …

Point Of Common Coupling (Pcc) Voltage Control Of A Grid-Connected Solar Photovoltaic (Pv) System, Brian K. Perera, Philip Ciufo, Sarath Perera

Dr Philip Ciufo

In future low voltage grids, with multiple inverter interfaced sources connected, voltage regulation may become a necessary task. The potential exists for inverter interfaced sources to be deployed to regulate the voltage at the point of common coupling (PCC) of each inverter interfaced sources. The PCC voltage regulation is attainable with inverter interfaced sources by dynamically controlling the amount of reactive power injected to the power distribution grid by individual systems. In the current research, a closed-loop controller is proposed to regulate the PCC voltage of a solar photovoltaic (PV) system that is connected to a single-phase power distribution feeder …

Over-Voltage Mitigation Within Distribution Networks With A High Renewable Distributed Generation Penetration, Joel Kennedy, Philip Ciufo, Ashish Agalgaonkar

Dr Philip Ciufo

The rapid growth of grid-connected distributed generation has increased the likelihood of over-voltage occurrences in distribution networks. In recent times, much research has taken place in order to develop a control strategy to mitigate the voltage rise problem. However, most of the published strategies require re-tuning when additional resources are connected, or have a strong dependence on network parameters, such as fault level. This paper proposes a novel over-voltage mitigation scheme that has many advantages not observed in literature. Firstly, the control scheme can integrate with an existing feeder in a plug-and-play fashion. No prior analysis is necessary to configure …

Creativity In Scientific Teams: Unpacking Novelty And Impact, You-Na Lee, John P. Walsh, Jian Wang

Jian Wang

Comparing Particle Swarms For Tracking Extrema In Dynamic Environments, Xiaodong Li, Hoa K. Dam

Xiaodong Li

This work presents a comparative study of particle swarm models on their abilities to track extrema in dynamic environments. A standard PSO, two randomized PSOs, and a fine-grained PSO are evaluated in non-trivial multimodal dynamic environments involving small constant step changes, different large step changes, and chaotic step changes of the extrema. DF1 proposed by Morrison and De Jong is used to generate these three types of dynamics (1999). Our results indicate that PSO and its variants are able to perform reasonably well in a 2-dimensional variable space, whereas perform well to a less extent in a 10-dimensional variable space. …

What Is An Emerging Technology?, Daniele Rotolo, Diana Hicks, Ben Martin

Diana Hicks

Despite the growing interest around the emergence of novel technologies, especially from the policy-making perspective, there is still no consensus on what classifies a technology as ’emergent’. The present paper aims to fill this gap by developing a definition of ’emerging technologies’ and a framework for their detection and analysis. The definition is developed by combining a basic understanding of the term and in particular the concept of ’emergence’ with a review of key innovation studies dealing with definitional issues of technological emergence. The resulting definition identifies five attributes that feature in the emergence of novel technologies. These are: (i) …

Energy Loss Rate Of A Charged Particle In Hgte/(Hgte, Cdte) Quantum Wells, Qinjun Chen, Yee Sin Ang, Xiaolin Wang, R A. Lewis, Chao Zhang

Yee Sin Ang

The energy loss rate (ELR) of a charged particle in a HgTe/(HgTe, CdTe) quantum well is investigated. We consider scattering of a charged particle by the bulk insulating states in this type of topological insulator. It is found that the ELR characteristics due to the intraband excitation have a linear energy dependence while those due to interband excitation depend on the energy exponentially. An interesting quantitative result is that for a large range of the incident energy, the mean inelastic scattering rate is around a few terahertz.

Chiral-Like Tunneling Of Electrons In Two-Dimensional Semiconductors With Rashba Spin-Orbit Coupling, Yee Sin Ang, Zhongshui Ma, C Zhang

Yee Sin Ang

The unusual tunneling effects of massless chiral fermions (mCF) and massive chiral fermions (MCF) in a single layer graphene and bilayer graphene represent some of the most bizarre quantum transport phenomena in condensed matter system. Here we show that in a two-dimensional semiconductor with Rashba spin-orbit coupling (R2DEG), the real-spin chiral-like tunneling of electrons at normal incidence simultaneously exhibits features of mCF and MCF. The parabolic branch of opposite spin in R2DEG crosses at a Dirac-like point and has a band turning point. These features generate transport properties not found in usual two-dimensional electron gas. Albeit its p Berry phase, …

Nonlinear Optical Response Of Graphene Superlattice In Terahertz Frequency Regime, Yee Sin Ang, Chao Zhang

Yee Sin Ang

We investigate the nonlinear optical response of a Kronig-Penney type graphene superlattice in which the Fermi velocity of the massless Dirac quasiparticle anisotropically depends on the direction of propagation. Such velocity anisotropy results in enhanced nonlinear optical response in terahertz frequency regime.

A Comparative Analysis Of Multichannel Data Acquisition Systems For Quality Assurance In External Beam Radiation Therapy, Iolanda Fuduli, Claudiu Porumb, Anthony Espinoza, Abdullah Aldosari, Martin Carolan, Michael Lf Lerch, Peter E. Metcalfe, Anatoly Rosenfeld, Marco Petasecca

Anthony A Espinoza Mr

The paper presents a comparative study performed by the Centre of Medical Radiation Physics (CMRP) on three multichannel Data Acquisition Systems (DAQ) based on different analogue front-ends to suit a wide range of radiotherapy applications. The three front-ends are: a charge-to-frequency converter developed by INFN Torino, an electrometer and a charge-to-digital converter (both commercial devices from Texas Instruments). For the first two (named DAQ A and B), the CMRP has designed the read-out systems whilst the third one (DAQ C) comes with its own evaluation board. For the purpose of the characterization DAQ A and DAQ B have been equipped …

The Feasibility Study And Characterziation Of A Two-Dimensional Diode Array In “Magic Phantom” For High Dose Rate Brachytherapy Quality Assurance, A Espinoza, B Beeksma, M Petasecca, I Fuduli, C Porumb, D L. Cutajar, S Corde, M A. Jackson, M Lf Lerch, Anatoly B. Rosenfeld

Anthony A Espinoza Mr

High dose rate (HDR) brachytherapy is a radiation treatment technique capable of delivering large dose rates to the tumor. Radiation is delivered using remote afterloaders to drive highly active sources (commonly 192Ir with an air KERMA strength range between 20 000 and 40 000 U, where 1 U = 1 uGy m2/h in air) through applicators directly into the patient's prescribed region of treatment. Due to the obvious ramifications of incorrect treatment while using such an active source, it is essential that there are methods for quality assurance (QA) that can directly and accurately verify the treatment plan and the …

X-Tream: A Novel Dosimetry System For Synchrotron Microbeam Radiation Therapy, M Petasecca, A Cullen, I Fuduli, A Espinoza, C Porumb, C Stanton, A H. Aldosari, E Brauer-Krisch, H Requardt, A Bravin, V Perevertaylo, Anatoly B. Rosenfeld, M L. F Lerch

Anthony A Espinoza Mr

Microbeam Radiation Therapy (MRT) is a radiation treatment technique under development for inoperable brain tumors. MRT is based on the use of a synchrotron generated X-ray beam with an extremely high dose rate ( ~ 20 kGy/sec), striated into an array of X-ray micro-blades. In order to advance to clinical trials, a real-time dosimeter with excellent spatial resolution must be developed for absolute dosimetry. The design of a real-time dosimeter for such a radiation scenario represents a significant challenge due to the high photon flux and vertically striated radiation field, leading to very steep lateral dose gradients. This article analyses …

Optimal Energy For Cell Radiosensitivity Enhancement By Gold Nanoparticles Using Synchrotron-Based Monoenergetic Photon Beams, Wan Nordiana Rahman, Stephanie Corde, Naoto Yagi, Siti Aishah Abdul Aziz, Nathan Annabell, Moshi Geso

Stéphanie Corde

Gold nanoparticles have been shown to enhance radiation doses delivered to biological targets due to the high absorption coefficient of gold atoms, stemming from their high atomic number (Z) and physical density. These properties significantly increase the likelihood of photoelectric effects and Compton scattering interactions. Gold nanoparticles are a novel radiosensitizing agent that can potentially be used to increase the effectiveness of current radiation therapy techniques and improve the diagnosis and treatment of cancer. However, the optimum radiosensitization effect of gold nanoparticles is strongly dependent on photon energy, which theoretically is predicted to occur in the kilovoltage range of energy. …

Scientific Teams: Self-Assembly, Fluidness, And Interdependence, Jian Wang, Diana Hicks

Jian Wang

Knowledge In Society And The Knowledge Society: Opening The Debate For A New Millennium, Ananya Vajpeyi

Ananya Vajpeyi

No abstract provided.

Reageren Op Problematisch Wetenschappelijk Gedrag Voorbij De Moralisering : Een Ander Wetenschapsbeleid Is Mogelijk !, Serge Gutwirth, Jenneke Christiaens

Serge Gutwirth

In deze bijdrage gaan we in op een aantal vragen die rijzen bij het reageren op wetenschapsfraude. In een eerdere bijdrage -"It's the science policy, stupid ! Over wetenschapsfraude als bliksemafleider"- (http://works.bepress.com/serge_gutwirth/109/) hebben we reeds aandacht besteed aan wetenschapsfraude, en meer bepaald aan de wijze waarop die ten aanzien van de praktijk van de wetenschap en in wisselwerking met haar milieu kan worden begrepen. Omdat nadenken over de reactie(s) op wetenschapsfraude afhankelijk is van hoe wetenschappen worden geconcipieerd vormen onze bevindingen van dit eerdere stuk het vertrekpunt van de huidige bijdrage: in het eerste deel zullen we er de conceptuele …

Les Sciences Et Leurs Problèmes : La Fraude Scientifique, Un Moyen De Diversion ?, Serge Gutwirth, Jenneke Christiaens

Serge Gutwirth

Pour mieux comprendre la fraude scientifique et l’attention qu’on lui porte, les auteurs l’analysent au départ d’une description de ce qui fait la singularité générique du travail scientifique et de ce qui le caractérise uniquement. Cette approche fait rapidement émerger deux problèmes. D’une part, s’impose le constat de la diversité des sciences, des pratiques scientifiques, de leurs objets d’études et des conséquences de cette pluralité, dès lors que toutes les sciences ne fonctionnent pas de la même façon. De l’autre, il faut rendre compte du fait que la science et la recherche ont subi d’importantes transformations ces 50 dernières années …

Lo Stato Innovatore: Come Funziona E Perché Ci Serve. Recensione A “Lo Stato Innovatore” Di Mariana Mazzucato, Matteo Lucchese, Mario Pianta

Mario Pianta

No abstract provided.

The Virtuous Circle Of Innovation In Italian Firms, Francesco Bogliacino, Matteo Lucchese, Leopoldo Nascia, Mario Pianta

Mario Pianta

The “virtuous circle” between innovative inputs, outputs and economic performance is investigated in this article with a three equation model highlighting feedback loops and simultaneous relations. An empirical test is carried out considering innovative expenditure, innovative turnover and economic results in a sample of Italian manufacturing firms which are ‘serial innovators’. We use data for the period 2000-2008 from a rich panel of Italian firms over 50 employees drawn from ISTAT, the National Institute of Statistics, including data from three waves of Community Innovation Surveys. The model we use extends the one developed at the industry level by Bogliacino and …

Copyright And Ownership Of Fan Created Works: Fanfiction And Beyond, Raizel Liebler

Raizel Liebler