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Articles 1 - 20 of 20
Full-Text Articles in Engineering
Power-Weighted Divergences For Relative Attenuation And Delay Estimation, Ruairí De Fréin, Scott T. Rickard Prof
Power-Weighted Divergences For Relative Attenuation And Delay Estimation, Ruairí De Fréin, Scott T. Rickard Prof
Articles
Power-weighted estimators have recently been proposed for relative attenuation and delay estimation in blind source separation. Their provenance lies in the observation that speech is approximately windowed-disjoint orthogonal (WDO) in the time-frequency (TF) domain; it has been reported that using WDO, derived from TF representations of speech, improves mixing parameter estimation. We show that power-weighted relative attenuation and delay estimators can be derived from a particular case of a weighted Bregman divergence. We then propose a wider class of estimators, which we tune to give better parameter estimates for speech.
Pattern Reconfigurable Back-To-Back Microstrip Patch Antenna, Kansheng Yang, Xiulong Bao, Patrick Mcevoy, Max Ammann
Pattern Reconfigurable Back-To-Back Microstrip Patch Antenna, Kansheng Yang, Xiulong Bao, Patrick Mcevoy, Max Ammann
Articles
A back-to- back microstrip patch antenna with a switchable pattern is proposed for WLAN applications. The patch elements, printed on FR-4 substrates with a common ground plane, are switched with a single-pole double-throw PIN diode circuit. Switching the feed selects either of two identical radiation patterns in the opposing hemispheres for spatial diversity that would benefit a distributed network.
Technological Assessment Of Different Solar-Biomass Systems For Hybrid Power Generation In Europe, C. M. Iftekhar Hussain, Brian Norton, Aidan Duffy
Technological Assessment Of Different Solar-Biomass Systems For Hybrid Power Generation In Europe, C. M. Iftekhar Hussain, Brian Norton, Aidan Duffy
Articles
Solar Tower thermal (ST), Parabolic Trough thermal (PT), Linear Fresnel thermal (LF) and Solar PV are discussed in the context of suitability for hybridization with biomass in Europe. Technical, economical and climate data have been compared to identify the key drivers of technology selection in setting up large scale solar-biomass hybrid power plants. The sole solar-biomass hybrid power plant is currently in operation in Spain uses PT technology due to its performance characteristics, comparatively easy installation process compared to ST and relatively higher heat and optical gain than LF. The climate condition in the EU shows that the region within …
Research Note: On The Magnitude Of Error In The Calculation Of Mean Room Surface Exitance, James Duff
Research Note: On The Magnitude Of Error In The Calculation Of Mean Room Surface Exitance, James Duff
Articles
Two formulae currently exist for calculating mean room surface exitance. This research note explains and demonstrates that one of these formulae is erroneous under certain conditions and stresses that the alternative expression should generally be used for computing mean room surface exitance.
Source Separation Approach To Video Quality Prediction In Computer Networks, Ruairí De Fréin
Source Separation Approach To Video Quality Prediction In Computer Networks, Ruairí De Fréin
Articles
Time-varying loads introduce errors in the estimated model parameters of service-level predictors in Computer Networks. A load-adjusted modification of a traditional unadjusted service-level predictor is contributed, based on Source Separation (SS). It mitigates these errors and improves service-quality predictions for Video-on-Demand (VoD) by :6 to 2dB.
Amorphous Silicon Solar Vivaldi Antenna, Oisin O'Conchubhair, Kansheng Yang, Patrick Mcevoy, Max Ammann
Amorphous Silicon Solar Vivaldi Antenna, Oisin O'Conchubhair, Kansheng Yang, Patrick Mcevoy, Max Ammann
Articles
An ultra-wideband solar Vivaldi antenna is proposed. Cut from amorphous silicon cells, it maintains a peak power at 4.25 V which overcomes a need for lossy power management components. The wireless communications device can yield solar energy or function as a rectenna for dual-source energy harvesting. The solar Vivaldi performs with 0.5 - 2.8 dBi gain from 0.95 - 2.45 GHz and in rectenna mode, it covers three bands for wireless energy scavenging.
Gravity As An Ultra-Low Frequency Scattering Efect, Jonathan Blackledge
Gravity As An Ultra-Low Frequency Scattering Efect, Jonathan Blackledge
Articles
Under the weak gravitational field appromination and for the 00-component of the stress-energy tensor, Einstein's field equations for the gravitational potential. By considering Newton' field equation to be the result of an ultra-low frequency scattering effect (in the limiting) case, this work introduces a model where gravitational field is taken to be the result of an ultra-low frequency gravitational wave (propagating in a near-Cartesian Minkowski space) scattering from an object (a mass)
Time Series Analysis For A 1/Tb Memory Function And Comparison With The Lyapunov Exponent Using Volatility Scaling, Paddy Walsh, Jonathan Blackledge
Time Series Analysis For A 1/Tb Memory Function And Comparison With The Lyapunov Exponent Using Volatility Scaling, Paddy Walsh, Jonathan Blackledge
Articles
Being able to provide accurate forecasts on the trending behaviour of time series is important in a range of applications involving the real time evolution of signals, most notable in financial time series analysis but control engineering in general. A critical solution for providing high accuracy forecasts is the filtering operation used to identify the position in time at which a trend occurs subject to a time delay factor that is inherent in the filtering strategy used. The paper explores this strategy and presents some example results that provide a quantitative measure of the accuracy used.
Optimized Sliding Mode Control To Maximize Existence Region For Single-Phase Dynamic Voltage Restorers, Samet Biricik, Hasan Komurcugil
Optimized Sliding Mode Control To Maximize Existence Region For Single-Phase Dynamic Voltage Restorers, Samet Biricik, Hasan Komurcugil
Articles
This paper presents an optimized sliding mode control (SMC) strategy to maximize existence region for single-phase dynamic voltage restorers. It is shown analytically that there exists an optimum sliding coefficient which enlarges the existence region of the sliding mode to its maximum. Also, it is pointed out that the optimum sliding coefficient improves the dynamic response. In addition, a double-band hysteresis control which ensures the switching of a transistor in the voltage source inverter during a half-cycle while it remains either on or off in the other half cycle is used to mitigate the switching frequency. The theoretical considerations and …
On-Chip Integratable All-Optical Quantizer Using Strong Cross-Phase Modulation In A Silicon-Organic Hybrid Slot Waveguide, Zhe Kang, Jinhui Yuan, Xianting Zhang, Xinzhu Sang, Kuiru Wang, Qiang Wu, Binbin Yan, Feng Li, Xian Zhou, Kangping Zhong, Guiyao Zhou, Chongxiu Yu, Gerald Farrell, Chao Lu, Hwa Yaw Tam, P. K. A. Wai
On-Chip Integratable All-Optical Quantizer Using Strong Cross-Phase Modulation In A Silicon-Organic Hybrid Slot Waveguide, Zhe Kang, Jinhui Yuan, Xianting Zhang, Xinzhu Sang, Kuiru Wang, Qiang Wu, Binbin Yan, Feng Li, Xian Zhou, Kangping Zhong, Guiyao Zhou, Chongxiu Yu, Gerald Farrell, Chao Lu, Hwa Yaw Tam, P. K. A. Wai
Articles
High performance all-optical quantizer based on silicon waveguide is believed to have significant applications in photonic integratable optical communication links, optical interconnection networks and real-time signal processing systems. In this paper, we propose an integratable all-optical quantizer for on-chip and low power consumption all-optical analog-to-digital converters. The quantization is realized by the strong cross-phase modulation and interference in a silicon-organic hybrid (SOH) slot waveguide based Mach-Zehnder interferometer. By carefully designing the dimension of the SOH waveguide, large nonlinear coefficients up to 16,000 and 18,069 W−1/m for the pump and probe signals can be obtained respectively, along with a low pulse …
Three-Level Hysteresis Current Control Strategy For Three-Phase Four-Switch Shunt Active Filters, Samet Biricik, Hasan Komurcugil
Three-Level Hysteresis Current Control Strategy For Three-Phase Four-Switch Shunt Active Filters, Samet Biricik, Hasan Komurcugil
Articles
In this study, a three-level hysteresis current-control (HCC) strategy is proposed for three-phase four-switch shunt active power filters. The four-switch topology which utilises four switching devices together with two series connected capacitors is able to reduce the cost, switching losses and improve the reliability of system. In this topology, when the current control of phases A and B is achieved successfully, the current control of phase C which is connected to the midpoint of the series connected capacitors is achieved automatically. The current control is achieved by using a three-level HCC strategy. An important consequence of using this control strategy …
Robust Fuzzy-Sliding Mode Based Upfc Controller For Transient Stability Analysis In Autonomous Wind-Diesel-Pv Hybrid System, Asit Mohanty, Sandipan Patra, Prakash K. Ray
Robust Fuzzy-Sliding Mode Based Upfc Controller For Transient Stability Analysis In Autonomous Wind-Diesel-Pv Hybrid System, Asit Mohanty, Sandipan Patra, Prakash K. Ray
Articles
This study presents a comparative study of transient stability and reactive power compensation issues in an autonomous wind–diesel-photovoltaic based hybrid system (HS) using robust fuzzy-sliding mode based unified power flow controller (UPFC). A linearised small-signal model of the different elements of the HS is considered for the transient stability analysis in the HS under varying loading conditions. An IEEE type 1 excitation system is considered for the synchronous generator in the HS, with negligible saturation characteristic, for detailed voltage stability analysis. It is noted from the simulation results that the performance of UPFC is superior to static VAR compensator and …
New Hybrid Active Power Filter For Harmonic Current Suppression And Reactive Power Compensation, Samet Biricik, Ozgur Cemal Ozerdem, Soydan Redif, Mustafa Sezai Dincer
New Hybrid Active Power Filter For Harmonic Current Suppression And Reactive Power Compensation, Samet Biricik, Ozgur Cemal Ozerdem, Soydan Redif, Mustafa Sezai Dincer
Articles
In the case of undistorted and balanced grid voltages, low ratio shunt Active Power Filters (APFs) can give unity power factors and achieve current harmonic cancellation. However, this is not possible when source voltages are distorted and unbalanced. In this study, the cost-effective hybrid active power filter (HAPF) topology for satisfying the requirements of harmonic-current suppression and non-active power compensation for industry is presented. An effective strategy is developed to observe the effect of the placement of power capacitors and LC filters with the shunt active power filter. A new method for alleviating the negative effects of a non-ideal grid …
A Different Type Of Lighting Research: A Qualitative Methodology, Kevin Kelly
A Different Type Of Lighting Research: A Qualitative Methodology, Kevin Kelly
Articles
As lighting researchers we can learn from our colleagues in the humanities who have progressed Qualitative Research methods to a high level of rigour. We should consider using Qualitative Research Methods more. Such methods allow exploration of complex issues involving human behaviour and facilitate researchers to address difficult to answer questions that otherwise go unanswered. Good quality Qualitative Research can provide rich explanations of what went on in a given situation. Validity and Reliability are considered differently with this type of research methodology. This paper attempts to identify when qualitative research is appropriate, what questions it can answer in lighting …
A Techno-Economical Appraisal Of A Pv Domestic Plant On A Irish Dwelling, Roberto Sandano
A Techno-Economical Appraisal Of A Pv Domestic Plant On A Irish Dwelling, Roberto Sandano
Articles
A comprehensive study of a domestic PV installation is addressed in this paper. A series of economic results are presented for a domestic installation in Ireland.
Utilising A Loop Structure To Allow A Microfiber Coupler With Larger Taper Diameters To Be Used For Sensing, Fangfang Wei, Gerald Farrell, Qiang Wu, Yuliya Semenova
Utilising A Loop Structure To Allow A Microfiber Coupler With Larger Taper Diameters To Be Used For Sensing, Fangfang Wei, Gerald Farrell, Qiang Wu, Yuliya Semenova
Articles
This paper examines a technique that utilizes a Sagnac loop with a microfiber coupler (MFC) as a coupler which allows the MFC to operate effectively as a sensor but with larger than normal tapered fiber diameters. The proposed structure is found to be suitable for temperature and refractive index (RI) sensing. It is shown that a variation in the surrounding of the MFC RI results in a shift of the output spectrum, while a temperature variation leads to changes in the intensity of the interference dips. A decrease in the waist diameter of the MFC results in an increase in …
Computational Tracking Of Shear-Mediated Platelet Interactions With Von Willebrand Factor, Adam Ralph, Martin Somers, Jonathan Cowman, Bruno Voisin, Emma Hogan, Hannah Dunne, Eimear Dunne, Barry Byrne, Nigel Kent, Antonio J. Ricco, Dermot Kenny, Simon Wong
Computational Tracking Of Shear-Mediated Platelet Interactions With Von Willebrand Factor, Adam Ralph, Martin Somers, Jonathan Cowman, Bruno Voisin, Emma Hogan, Hannah Dunne, Eimear Dunne, Barry Byrne, Nigel Kent, Antonio J. Ricco, Dermot Kenny, Simon Wong
Articles
The imaging of shear-mediated dynamic platelet behavior interacting with surface-immobilized von Willebrand factor (vWF) has tremendous potential in characterizing changes in platelet function for clinical diagnostics purposes. However, the imaging output, a series of images representing platelets adhering and rolling on the surface, poses unique, non-trivial challenges for software algorithms that reconstruct the positional trajectories of platelets. We report on an algorithm that tracks platelets using the output of such flow run experiments, taking into account common artifacts encountered by previously-published methods, and we derive seven key metrics of platelet dynamics that can be used to characterize platelet function. Extensive …
Monitoring Voip Speech Quality For Chopped And Clipped Speech, Andrew Hines, Jan Skoglund, Anil C. Kokaram, Naomi Harte
Monitoring Voip Speech Quality For Chopped And Clipped Speech, Andrew Hines, Jan Skoglund, Anil C. Kokaram, Naomi Harte
Articles
No abstract provided.
State-Of-The-Art Review Of Cathodic Protection For Reinforced Concrete Structures, Aimee Byrne, Niall Holmes, Brian Norton
State-Of-The-Art Review Of Cathodic Protection For Reinforced Concrete Structures, Aimee Byrne, Niall Holmes, Brian Norton
Articles
Cathodic protection (CP) limits the corrosion of a metal surface by making it the cathode of an electrochemical cell. This can be achieved either by using a more active sacrificial anode to create a driving current, or by using inert anodes and impressing a current onto the cathode surface using an external direct current (DC) source. Impressed current cathodic protection (ICCP) is preferred where widespread protection is required, particularly in reinforced concrete structures. ICCP needs a constant DC power supply that is usually provided through a grid connection or independent generators. This paper presents the currently available CP systems for …
Human Factors Issues And The Risk Of High Voltage Equipment: Are Standards Sufficient To Ensure Safety By Design?, Maria Chiara Leva, Roberta Pirani, Micaela De Michela, Paul Clancy
Human Factors Issues And The Risk Of High Voltage Equipment: Are Standards Sufficient To Ensure Safety By Design?, Maria Chiara Leva, Roberta Pirani, Micaela De Michela, Paul Clancy
Articles
High voltage equipment is mostly designed according to technically prescriptive standards requirements based on electrical engineering safety principles. However a more risk-based approach to standards and regulation may be advisable to enable designer and user to take an active role in establishing that their installation is inherently safe. The use of Gas Insulated Switchgear (GIS) for instance is enabling the new substation to be housed indoors and condensed into around one quarter of the space. The manufacturers argue that design improvements in GIS make it virtually “maintenance free”, comply with all the relevant standards. However some of these improvements have …