Science and Technology Studies Commons^™

Ieee Istas13- People As Sensors: The Social Implications Of Living In A Smart World, Alexander Hayes, Katina Michael, Nick Rheinberger

Alexander Hayes Mr.

What is the technological trajectory of people wearing sensors? What are the benefits, risks and costs? What is the vibe going to be like at ISTAS13 with people like Marvin Minsky and Ray Kurzweil attending? What do you hope to gain from the meeting? Can we foresee a time that all glasses will be embedded with sensors? What are the implications? E.g. in the higher education sector? What about the gathering of evidence by law enforcement? What is point of eye?

Workshop | Body Worn Video Recorders: The Socio-Technical Implications Of Gathering Direct Evidence, Katina Michael, Alexander Hayes

Alexander Hayes Mr.

- From in-car video recording to body-worn video recording

- Exploring available technologies: how do they work, pros and cons

- Storing direct evidence in secure storage: factors to consider

- Citizens “shooting” back with POV tech – what are their rights?

- Crowdsourced sousveillance- harnessing public data for forensic profiling

- Police force policies and practices on the application of new media

The Ocean Thermal Energy Conversion Strategies And Analysis Of Current Challenges, Lasantha Meegahapola, Lanka Udawatta, Sanjeeva Witharana

Dr Lasantha G Meegahapola

This paper presents different roots of Ocean Thermal Energy Conversion (OTEC) strategies and challenges faced in terms of efficiency and economy of OTEC plants. The conversion strategies primarily focus on open cycle, closed cycle and hybrid plants. The efficiency studies mainly skew towards the effect of plant distance and thermal gradient towards plant efficiency. The economic analysis is based upon the effect of per unit cost for OTEC plant together with other important considerations such as Plant Factor (PF) and offshore distance, which determine the cost of power generation. Some illustrative examples are also provided using the derived equations under …

Impact Of Wind Generator Control Strategies On Flicker Emission In Distribution Networks, Lasantha Meegahapola, Sarath Perera

Dr Lasantha G Meegahapola

Renewable power generators are increasingly being integrated to electricity networks to achieve future renewable energy targets in power generation. In particular, wind power generation has already reported substantial penetration levels in electricity networks. Traditionally, flicker phenomenon is considered to be one of the power quality issues in power distribution networks due to fluctuating consumer loads connected to the network. Large-scale integration of wind power generators may create significant voltage fluctuations in distribution feeders due to stochastic and intermittent nature of the wind resources. This study aims to investigate and characterize the flicker emission under different control strategies for DFIG based …

Impact Of Wind Generation Mix On Transient Stability For An Interconnected Power System, Lasantha Meegahapola, Damian Flynn, Jason Kennedy, Tim Littler

Dr Lasantha G Meegahapola

The rapid growth of wind generation in many European countries is pushing power systems into uncharted territory. As additional wind generators are installed, the changing generation mix may impact on power system stability. This paper adopts the New England 39 bus system as a test system for transient stability analysis. Thermal generator models are based on a likely future plant mix for existing systems, while varying capacities of fixed-speed induction generators (FSIG) and doubly-fed induction generators (DFIG) are considered. The main emphasis here has been placed on the impact of wind technology mix on inter-area oscillations following transient grid disturbances. …

Characterisation Of Flicker Emission And Propagation In Distribution Networks With Bi-Directional Power Flows, D Perera, L Meegahapola, S Perera, P Ciufo

Dr Lasantha G Meegahapola

With the increasing penetration levels of intermittent and fluctuating energy sources such as wind generating systems in the electricity grid, resulting voltage fluctuations and flicker can be expected to become an important power quality considerations. Due to significant bidirectional power flows resulting from large renewable power generation systems connected to downstream, voltage fluctuations may propagate from downstream to upstream. The work presented in this paper investigates and characterises flicker emission and propagation resulting from fluctuating generating sources connected to a distribution network. Mathematical models are developed for flicker emission under different generator control strategies and flicker propagation to upstream network. …

Comparative Analysis Of Dynamic Line Rating Models And Feasibility To Minimise Energy Losses In Wind Rich Power Networks, Mathew Simms, Lasantha Meegahapola

Dr Lasantha G Meegahapola

Wind power generation has indicated an exponential increase during last two decades and existing transmission network infrastructure is increasingly becoming inadequate to transmit remotely generated wind power to load centres in the network. The dynamic line rating (DLR) is one of the viable solutions to improve the transmission line ampacity during high wind penetration without investing on an additional transmission network. The main objective of this study is to identify the basic differences between two main line rating standards, since transmission network service providers (TNSPs) heavily depend on these two standards when developing their line rating models. Therefore, a parameter …

Flicker Mitigation Strategy For Dfigs During Variable Wind Conditions, Lasantha Meegahapola, Brendan Fox, Damian Flynn

Dr Lasantha G Meegahapola

This paper presents a flicker mitigation scheme for the doubly-fed induction generator (DFIG) during variable wind conditions. The flicker mitigation strategy was developed based on the distribution line X/R ratio and the active power deviation from the average active power during variable wind conditions. Flicker emission was analyzed using a flicker meter based on the IEC standards. Both short-term and long-term flicker severities were analyzed during the time period of study. The flicker mitigation strategy was evaluated under different system conditions such as X/R ratio, distribution line length, shortcircuit capacity (SCC), and wind variability. It is shown that the proposed …

Optimal Power Flow With Variable Wind Conditions, S Durairaj, L Meegahapola, D Flynn, B Fox

Dr Lasantha G Meegahapola

This paper presents simulation studies of an electric arc furnace (EAF) model in the MATLAB/SIMULINK environment. EAF was modeled as a current source controlled by a non-linear resistance. Voltage flicker, a phenomenon of annoying light intensity fluctuation, caused by EAF, has been a major power quality concern for both power companies and customers. A model was developed for the electric arc furnace and it was applied in the simulation studies of distribution static synchronous compensator (DSTATCOM) for voltage flicker mitigation. The controller for DSTATCOM was designed based on DQ-model for the reactive power management which helps in the mitigation of …

Voltage And Power Quality Improvement Strategy For A Dfig Wind Farm During Variable Wind Conditions, L Meegahapola, T Littler, B Fox, J Kennedy, D Flynn

Dr Lasantha G Meegahapola

This paper presents a voltage and power quality enhancement scheme for a doubly-fed induction generator (DFIG) wind farm during variable wind conditions. The wind profiles were derived considering the measured data at a DFIG wind farm located in Northern Ireland (NI). The aggregated DFIG wind farm model was validated using measured data at a wind farm during variable generation. The voltage control strategy was developed considering the X/R ratio of the wind farm feeder which connects the wind farm and the grid. The performance of the proposed strategy was evaluated for different X/R ratios, and wind profiles with different characteristics. …

Impact On Transient And Frequency Stability For A Power System At Very High Wind Penetration, Lasantha Meegahapola, Damian Flynn

Dr Lasantha G Meegahapola

This paper analyzes the impact on transient and frequency stability for a power system at very high wind penetration (40% wind). Wind penetration is based on the doubly-fed induction generator (DFIG), and a systematic approach has been adopted for wind power integration. A sensitivity analysis has been carried out for each wind integration scenario and for different wind generator loading conditions. A range of fault locations has been selected for stability analysis based on the proximity to synchronous generation and wind farms. The analysis has shown that transient stability performance is subject to fault location in the network, especially when …

Optimal Allocation Of Reactive Power Resources To Minimise Losses And Maintain System Security, Eknath Vittal, Lasantha Meegahapola, Damian Flynn, Andrew Keane

Dr Lasantha G Meegahapola

Modern doubly-fed induction generator (DFIG) wind turbines have significant reactive power control capability, even during low wind speed conditions. This can improve system security by providing terminal voltage control at buses in the system. Generally, such control employs the full range of reactive power production from the turbine which can lead to increased system losses. By utilizing optimal power flow analysis, and limiting the range of reactive power production at certain wind farms, system losses can be minimized. If the reactive power of the wind farms are optimized to achieve the minimum system losses this may adversely affect the voltage …

Transient Stability Analysis Of A Power System With High Wind Penetration, Lasantha Meegahapola, Damian Flynn, Tim Littler

Dr Lasantha G Meegahapola

This paper presents transient stability analysis for a power system with high wind penetration. The transient stability has been evaluated based on two stability criteria: rotor angle stability and voltage stability. A modified IEEE-14 bus system has been used as the main study network and simulations have been conducted at several wind power penetration levels, defined as a fraction of total system generation. A wide range of scenarios have been presented based on the wind farm voltage at the point of connection, i.e. low voltage (LV) distribution level and high voltage (HV) transmission level, and the type of wind generator …

Multi-Objective Reactive Power Support From Wind Farms For Network Performance Enhancement, Lasantha Meegahapola, Brendan Fox, Tim Littler, Damian Flynn

Dr Lasantha G Meegahapola

This paper examines the ability of the doubly fed induction generator (DFIG) to deliver multiple reactive power objectives during variable wind conditions. The reactive power requirement is decomposed based on various control objectives (e.g. power factor control, voltage control, loss minimisation, and flicker mitigation) defined around different time frames (i.e. seconds, minutes, and hourly), and the control reference is generated by aggregating the individual reactive power requirement for each control strategy. A novel coordinated controller is implemented for the rotor-side converter and the grid-side converter considering their capability curves and illustrating that it can effectively utilise the aggregated DFIG reactive …

Voltage Security Constrained Reactive Power Optimization Incorporating Wind Generation, L G. Meegahapola, E Vittal, A Keane, D Flynn

Dr Lasantha G Meegahapola

This paper presents a comparative analysis between conventional optimal power flow (OPF) and voltage constrained OPF strategies with wind generation. The study has been performed using the New England 39 bus system with 12 doublyfed induction generator (DFIG) based wind farms installed across the network. A voltage security assessment is carried out to determine the critical wind farms for voltage stability enhancement. The power losses and individual wind farm reactive power generation have been compared with and without voltage stability constraints imposed on the OPF simulation. It is shown that voltage constrained OPF leads to much greater active power losses …

Dynamic Characteristics Of A Hybrid Microgrid With Inverter And Non- Inverter Interfaced Renewable Energy Sources: A Case Study, A V. Jayawardena, L G. Meegahapola, S Perera, D A. Robinson

Dr Lasantha G Meegahapola

Microgrids are becoming important constituents of electric power distribution networks. Microgrids are typically comprised of both inverter interfaced (e.g. double-fed induction generator (DFIG), solar-photovoltaic (PV) system) and non-inverter interfaced (e.g. synchronous generator) renewable energy generators (REGs), hence their dynamic characteristics are significantly different from the conventional grids comprised of centralised synchronous generators. Different inherent characteristics of REGs, power dispatch levels, relative REG capacities, and external grid characteristics are some of the important features of significant interest in relation to microgrid dynamic behaviour. For this study a microgrid model was developed in DIgSILENT Power Factory based on the IEEE-13 bus system …

Active Use Of Dfig Based Wind Farms For Transient Stability Improvement During Grid Disturbances, Lasantha Meegahapola, Damian Flynn, Jason Kennedy, Tim Littler

Dr Lasantha G Meegahapola

The doubly-fed induction generator (DFIG) now represents the dominant technology in wind turbine design. One consequence of this is limited damping and inertial response during transient grid disturbances. A 'decoupled' strategy is therefore proposed to operate the DFIG grid-side converter (GSC) as a static synchronous compensator (STATCOM) during a fault, supporting the local voltage, while the DFIG operates as a fixed-speed induction generator (FSIG) providing an inertial response. The modeling aspects of the decoupled control strategy, the selection of protection control settings, the significance of the fault location and operation at sub- and super-synchronous speeds are analyzed in detail. In …

Capability Curve Based Enhanced Reactive Power Control Strategy For Stability Enhancement And Network Voltage Management, Lasantha Meegahapola, Tim Littler, Sarath Perera

Dr Lasantha G Meegahapola

Reactive power has become a vital resource in modern electricity networks due to increased penetration of distributed generation. This paper examines the extended reactive power capability of DFIGs to improve network stability and capability to manage network voltage profile during transient faults and dynamic operating conditions. A coordinated reactive power controller is designed by considering the reactive power capabilities of the rotor-side converter (RSC) and the grid-side converter (GSC) of the DFIG in order to maximise the reactive power support from DFIGs. The study has illustrated that, a significant reactive power contribution can be obtained from partially loaded DFIG wind …

Fuzzy Logic And Artificial Neural Network Approaches In Odor Detection, Lasantha Meegahapola, J Karunadasa, Kasun Sandasiri, Damith Tharanga, Dammika Jayasekara

Dr Lasantha G Meegahapola

This paper presents the research segment of development of methodology for determining odor level of various applications using two different concepts; Fuzzy logic based algorithm and Artificial Neural Network (ANN) based algorithm. Three different gas sensors are used which respond to ammonia (NH3), hydrogen sulfide (H2S) and methane (CH4). Sensory fusion is achieved through processing the analog to digital converted values of sensor outputs using the algorithm to determine the odor level of various types of predetermined odors. Olfactometry was used to determine the desired outputs (odor levels) of the algorithms. Fuzzy logic algorithm uses Zadeh-Mamdani type Fuzzy inference system …

Optimization Of Frt Active Power Performance Of A Dfig During Transient Grid Faults, L Meegahapola, Damian Flynn, Tim Littler

Dr Lasantha G Meegahapola

Optimal fault ride-through (FRT) conditions for a doubly-fed induction generator (DFIG) during a transient grid fault are analyzed with special emphasis on improving the active power generation profile. The transition states due to crowbar activation during transient faults are investigated to exploit the maximum power during the fault and post-fault period. It has been identified that operating slip, severity of fault and crowbar resistance have a direct impact on the power capability of a DFIG, and crowbar resistance can be chosen to optimize the power capability. It has been further shown that an extended crowbar period can deliver enhanced inertial …

Flicker Propagation Analysis In Distribution Networks With Embedded Generation, D Perera, L Meegahapola, S Perera, P Ciufo

Dr Lasantha G Meegahapola

Embedded generators such as wind generators can produce observable voltage fluctuations during variable wind conditions hence flicker. The flicker produced by such intermittent and fluctuating generating sources can propagate to other parts of the distribution network while creating power quality issues in distribution feeders. This study presents a flicker emission analysis for a doubly-fed induction generator (DFIG) based wind farm and investigate the pertinent factors which influence flicker propagation and attenuation in distribution feeders. Study has shown that voltage fluctuations are significantly influenced by the attenuation characteristics of various load types (i.e. constant power, impedance and current loads) connected to …

Large Networks Of Vertical Multi-Layer Graphenes With Morphology-Tunable Magnetoresistance, Zengji Yue, Igor Levchenko, Shailesh Kumar, Donghan Seo, Xiaolin Wang, S X. Dou, Kostya Ken Ostrikov

Zengji Yue

We report on the comparative study of magnetotransport properties of large-area vertical few-layer graphene networks with different morphologies, measured in a strong (up to 10 T) magnetic field over a wide temperature range. The petal-like and tree-like graphene networks grown by a plasma enhanced CVD process on a thin (500 nm) silicon oxide layer supported by a silicon wafer demonstrate a significant difference in the resistance-magnetic field dependencies at temperatures ranging from 2 to 200 K. This behaviour is explained in terms of the effect of electron scattering at ultra-long reactive edges and ultra-dense boundaries of the graphene nanowalls. Our …

Velocity Distribution In Non-Uniform/Unsteady Flows And The Validity Of Log Law, Ishraq Alfadhli, Shu-Qing Yang, Muttucumaru Sivakumar

Ishraq Hamdan Alfadhli

This study investigates the longitudinal velocity profiles in steady and unsteady non-uniform open channel flows by analyzing the data available in the literature. It was found that for steady/unsteady flow in the Log law is applicable only in the inner region where y/hg

Distribution Of Reynolds Shear Stress In Steady And Unsteady Flows, Ishraq Alfadhli, Shu-Qing Yang, Muttucumaru Sivakumar

Ishraq Hamdan Alfadhli

This study investigates the Reynolds shear stress distribution in steady and unsteady non-uniform flows. Specifically, it deals with how to express the deviation of this turbulence characteristic from that of uniform flow line; it is found that flow acceleration can well represent the deviation of Reynolds shear stress from its standard linear distribution. By connecting the flow acceleration with Reynolds shear stress, the study demonstrates empirically that the linear distrubiton of Reynolds shear stress can be observed when the flow acceleration is zero; the concave distribution of Reynolds shear stress can be observed when the flow acceleration is negative or …

Does The Critical Shields Stress For Sediment Transport Depend On Channel-Bed Slope?, Ishraq Alfadhli, Shu-Qing Yang, Muttucumaru Sivakumar

Ishraq Hamdan Alfadhli

This paper investigates why the observed critical Shields stress for incipient sediment motion deviates from the Shields curve. This deviation is often described in the literature as due to measurement errors and non-uniformity of channel-bed slope or flows. On the contrary, this paper hypothesises the deviation as due to the presence of vertical velocity in open channel flows. We found that the existence of vertical velocity in non-uniform flows can lead to the deviation of critical shear stress from the standard Shield's diagram that is valid only in uniform flows, and the channel bed slope could not contribute to the …

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

Michael L.F. Lerch

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 …

A Real-Time In Vivo Dosimetric Verification Method For High-Dose Rate Intracavitary Brachytherapy Of Nasopharyngeal Carcinoma, Zhen-Yu Qi, Xiao-Wu Deng, X Cao, Shao-Min Huang, Michael Lerch, Anatoly Rosenfeld

Michael L.F. Lerch

Purpose: A real-time in vivo dosimetric verification method using metal-oxide-semiconductor field effect transistor (MOSFET) dosimeters has been developed for patient dosimetry in high-dose rate (HDR) intracavitary brachytherapy of nasopharyngeal carcinoma (NPC). Methods: The necessary calibration and correction factors for MOSFET measurements in 192Iridium source were determined in a water phantom. With the detector placed inside a custom-made nasopharyngeal applicator, the actual dose delivered to the tumor was measured in vivo and compared to the calculated values using a commercial brachytherapy planning system. Results: Five MOSFETs were independently calibrated with the HDR source, yielding calibration factors of 0.48 ± 0.007 cGymV. …

Performance Comparison Of Two Compact Multiplexed Readouts With Sensl's Spmarray4 For High-Resolution Detector Module, Yujin Qi, Xiaohui Zhang, Cuilan Zhao, Lihong Chen, Marco Petasecca, Mitra Safavi-Naeini, Michael Lerch, Anatoly Rosenfeld

Michael L.F. Lerch

The purpose of this study was to investigate a compact readout for silicon photomultiplier (SiPM) array in the development of high-resolution imaging detector to reduce the readout channels while maximizing the detectors performance. The detector module was composed of a LYSO scintillation crystal array and a SensL's SPMArray4. The crystal array was coupled to the SiPM array with a 2mm-thick silicone pad to improve the light sharing among the SiPM array elements. Three LYSO crystal arrays of 4x4, 8x8 and 12x12 crystal elements with pixel sizes of 3.2, 1.6 and 1.0 mm were investigated in this study. Two compact multiplexed …

Shear Lag And Eccentricity Effects Of Bolted Connections In Cold-Formed Steel Sections, Lip H. Teh, Veysel Yazici

Veysel Yazici

This paper examines the "three factors" approach previously presented by the senior author for determining the net section efficiency of a bolted cold-formed steel open profile. One objective is to ascertain that the net section efficiency is governed by three factors: the in-plane shear lag associated with stress concentration around a bolt hole that is also present in a flat sheet, the out-of-plane shear lag that is also present in a bi-symmetric I-section bolted at the flanges only, and the bending moment arising from the connection eccentricity with respect to the neutral axis. This paper presents the test results of …

Unconventional Block Shear Failures Of Bolted Connections In Cold-Reduced Steel Sheets, Lip H. Teh, Veysel Yazici

Veysel Yazici

This paper examines the block shear design equation proposed by the first author based on laboratory tests of bolted connection specimens failing in the conventional block shear failure mode. It shows that the explanation regarding the feasible mechanism of block shear failures previously provided by the first author does not necessarily apply to staggered bolted connections, in which the downstream bolts do not have the same edge distance. For staggered bolted connections, a block shear failure may occur through the shear rupture and tensile yielding mechanism for particular configurations, as demonstrated for the first time in this paper. The present …