bluuebunny/crossref_metadata_2025 huggingface dataset:
Weighting of Acoustic Cues to a Manner Distinction by Children With and Without Hearing Loss
Authors: Nittrouer Susan , Lowenstein Joanna H.
Published: March 2015

Purpose

Children must develop optimal perceptual weighting strategies for processing speech in their first language. Hearing loss can interfere with that development, especially if cochlear implants are required. The three goals of this study were to measure, for children with and without hearing loss: (a) cue weighting for a manner distinction, (b) sensitivity to those cues, and (c) real-world communication functions.

Method

One hundred and seven children (43 with normal hearing [NH], 17 with hearing aids [HAs], and 47 with cochlear implants [CIs]) performed several tasks: labeling of stimuli from /bɑ/-to-/wɑ/ continua varying in formant and amplitude rise time (FRT and ART), discrimination of ART, word recognition, and phonemic awareness.

Results

Children with hearing loss were less attentive overall to acoustic structure than children with NH. Children with CIs, but not those with HAs, weighted FRT less and ART more than children with NH. Sensitivity could not explain cue weighting. FRT cue weighting explained significant amounts of variability in word recognition and phonemic awareness; ART cue weighting did not.

Conclusion

Signal degradation inhibits access to spectral structure for children with CIs, but cannot explain their delayed development of optimal weighting strategies. Auditory training could strengthen the weighting of spectral cues for children with CIs, thus aiding spoken language acquisition.
Development and Simulation Testing of a Computerized Adaptive Version of the Philadelphia Naming Test
Authors: Hula William D. , Kellough Stacey , Fergadiotis Gerasimos
Published: March 2015

Purpose

The purpose of this study was to develop a computerized adaptive test (CAT) version of the Philadelphia Naming Test (PNT; Roach, Schwartz, Martin, Grewal, & Brecher, 1996), to reduce test length while maximizing measurement precision. This article is a direct extension of a companion article (Fergadiotis, Kellough, & Hula, 2015), in which we fitted the PNT to a 1-parameter logistic item-response-theory model and examined the validity and precision of the resulting item parameter and ability score estimates.

Method

Using archival data collected from participants with aphasia, we simulated two PNT-CAT versions and two previously published static PNT short forms, and compared the resulting ability score estimates to estimates obtained from the full 175-item PNT. We used a jackknife procedure to maintain independence of the samples used for item estimation and CAT simulation.

Results

The PNT-CAT recovered full PNT scores with equal or better accuracy than the static short forms. Measurement precision was also greater for the PNT-CAT than the static short forms, though comparison of adaptive and static nonoverlapping alternate forms showed minimal differences between the two approaches.

Conclusion

These results suggest that CAT assessment of naming in aphasia has the potential to reduce test burden while maximizing the accuracy and precision of score estimates.

Supplemental Material

https://doi.org/10.23641/asha.6170309
Spatially correlated channel estimation based on block iterative support detection for massive MIMO systems
Authors: Shen Wenqian , Dai Linglong , Gao Zhen , Wang Zhaocheng
Published: March 2015

Downlink channel estimation with low pilot overhead is an important and challenging problem in massive multiple‐input–multiple‐output (MIMO) systems due to the substantially increased MIMO channel dimension. A block iterative support detection (block‐ISD)‐based algorithm for downlink channel estimation to reduce the pilot overhead is proposed, which is achieved by fully exploiting the block sparsity inherent in the block‐sparse equivalent channel derived from the spatial correlations of MIMO channels. Furthermore, unlike conventional compressive sensing (CS) algorithms that rely on prior knowledge of the sparsity level, block‐ISD relaxes this demanding requirement and is thus more practically appealing. Simulation results demonstrate that block‐ISD yields better normalised mean square error (NMSE) performance than classical CS algorithms, and achieve a reduction of 84% pilot overhead compared with conventional channel estimation techniques.
PDbm: people detection benchmark repository
Authors: García‐Martín A. , Alcedo B. , Martínez J.M.
Published: March 2015

Following the approach of the change detection challenge, in order to facilitate the evaluation of new algorithms for people detection, a people detection benchmarking repository is presented. It includes realistic sequences, people detection ground truth and an evaluation framework. It will be updated based on received feedback, and will maintain a comprehensive ranking of submitted methods for years to come.
Accurate power model for mobile AMOLED displays
Authors: Park Jun‐Hyeok , Kim Young‐Jin
Published: March 2015

The display is a dominant power‐consuming component in mobile devices. The active matrix organic light‐emitting diode (AMOLED) display has been popular in mobile devices and its accurate power model is crucial for efficient power management. Existing power models do not consider the behaviours of the driving hardware components of AMOLED display modules. A new power model is proposed which considers the efficiency of an AMOLED DC–DC converter and the dependency of the driving circuits in a commercial AMOLED display module, and thus estimates an accurate power consumption value. Through extensive experiments using three well‐known image databases, the proposed power model is found to have lower error rates than the existing pixel‐based one for all the databases. Especially, for bright images the error rate of the new model amounts to only 0.59%, whereas that of the existing one is 8.48%.
Performance of ultra‐wideband time‐reversal systems under imperfect channel side information at the transmitter
Authors: Zia U. , Naqvi I. H. , Uppal M.
Published: March 2015

The performance of time‐reversal ultra‐wideband systems under imperfect channel side information at the transmitter (CSIT) is investigated. Considering CSIT imperfections caused by estimation errors as well as the channel's time‐varying nature, a bound is derived on the amount of channel decorrelation that the system can withstand while still achieving a target bit error rate floor. The theoretical results are supported by Monte Carlo simulations, indicating a robust performance in the presence of estimation errors and/or outdated CSIT.
Fast transient response high‐accuracy current‐sensing technique for step‐up DC–DC converter
Authors: Chi Yuan , Lai Xin‐Quan , Du Han‐Xiao
Published: March 2015

A novel current‐sensing technique with fast transient and high accuracy for a step‐up DC–DC converter is presented. This circuitry is applied for sensing the current flowing through the equivalent series resistor (ESR) of the inductor to obtain the inductor current information. It is achieved with a fast transient response circuit (FTRC), an operational amplifier, a current‐sensing stage and an overshoot current protection circuit. The process offsets of the transistors, which can increase the current‐sensing accuracy, and provide an additional current feedback loop to decrease the transient response time are compensated by the FTRC. When the sensed current is higher than the maximum value, the overcurrent protection (OCP) will be operating to let it shut down. This current‐sensing technique has been integrated in a step‐up DC–DC converter with standard 0.35 μm CMOS process. Experimental results show that the accuracy is higher than 98% and the transient response recovery time is ∼100 μs with load current changing from 3 A to 10 mA.
Extended‐aperture DOA estimation with unknown number of sources
Authors: Tian Ye , Xu He
Published: March 2015

Most of the existing direction‐of‐arrival (DOA) estimation methods require a priori knowledge of the source number, and can only estimate M − 1 sources with M sensors. A novel technique for a sparse signal reconstruction framework is proposed, which is unbiased and can extend the array aperture effectively. As a result, the proposed technique can not only estimate 2(M − 1) sources with M sensors, but also provide improved resolution and estimation accuracy. It can even obtain DOA estimation without knowing the number of sources.
4×, 3‐level, blind ADC‐based receiver
Authors: Kovacevic N. , Jalali M. S. , Liang J. , Ting C. , Sheikholeslami A. , Kibune M. , Tamura H.
Published: March 2015

The design of a 4× blind analogue‐to‐digital converter (ADC)‐based receiver implemented in 65 nm CMOS technology is presented. The ADC, which has three levels with two adjustable thresholds, effectively implements a speculative decision‐feedback equaliser. By reducing the ADC resolution and by simplifying the digital clock and data recovery design, the power consumption is reduced by a factor of 2 compared with previous works. Measurement results confirm a bit error rate of <10−12 at 5 Gbit/s with a high‐frequency jitter tolerance of 0.39 and 0.31 UIpp for a 9.3 and a 12.9 dB FR4 channel, respectively. The entire receiver consumes 63 and 86 mW for the respective channels.
Approximation of the maximum frequency of operation for point‐contact MIM diodes from DC current against voltage measurements
Authors: Snyder G. , Rhoades C. , Hagmann M.J.
Published: March 2015

Point‐contact metal–insulator–metal (MIM) diodes have been used for detection and mixing at frequencies as high as 520 THz. In detection, the current responsivity (CR), defined as the change in the DC current caused by an incremental change in the high‐frequency input power, depends on the dimensions of the diode and the test fixture. However, other researchers have shown that the intrinsic current responsivity (ICR) which sets an upper bound for the CR may be determined from DC current against voltage measurements. Additional calculations from DC measurements have been used to determine an upper bound for the maximum frequency of operation.
Height resolution analysis in geosynchronous SAR
Authors: Zeng Tao , Yin Wei , Ding Zegang , Long Teng
Published: March 2015

Owing to the curved track, geosynchronous synthetic aperture radar (GEO SAR) can obtain a height resolution. An accurate expression of the height resolution is derived for GEO SAR based on the generalised ambiguity function and the Doppler history difference between two adjacent targets at different heights. It is found that the height resolution is introduced by the accelerated motion or the curved track along the height direction in GEO SAR. Then, factors influencing the height resolution are analysed. The height resolution of GEO SAR can be improved by a longer integration time, a higher orbital inclination and a larger eccentricity. Finally, simulation results show the effectiveness of the proposed expression of height resolution.
Coherence‐selectable operation of external‐cavity semiconductor diode laser by intracavity polarisation control
Authors: Hyodo M. , Kawakami A. , Saito S. , Watanabe M. , Adachi M.
Published: March 2015

The operation of an external‐cavity semiconductor diode laser with selectable coherence and a tunable wavelength has been successfully demonstrated through the control of the intracavity polarisation state. The laser has an intracavity half‐wave plate that is able to rotate the orientation of the polarisation axis with regard to diffraction grating, where the grating acts as a polarisation‐ and wavelength‐selective element. As a result, it was possible to continuously sweep the correlation widths from 230 kHz to 2.0 MHz by simply rotating the half‐wave plate.
Nonlinear modelling of dynamic self‐heating in 28 nm bulk complementary metal–oxide semiconductor technology
Authors: Sahoo A.K. , Fregonese S. , Scheer P. , Celi D. , Juge A. , Zimmer T.
Published: March 2015

A new and simple approach for nonlinear modelling of the dynamic self‐heating effect in bulk complementary metal–oxide semiconductor (CMOS) field effect transistors is presented. Low‐frequency S‐parameter measurements are performed in 28 nm bulk CMOS technology at room temperature between a 10 kHz and 3 GHz frequency range and the thermal impedance (ZTH) of the devices is extracted. The proposed model is validated through the measurements for different bias points. The results obtained demonstrate a reasonable agreement between theoretical prediction and experimental data.
Miniaturised dual‐band filter with high selectivity using split ring scheme
Authors: Wu Guoan , Yang Lingling , Xu Qinfen
Published: March 2015

A novel miniaturised dual‐band bandpass filter (BPF) using improved split ring λ/4 resonator and stepped impedance resonator (SIR) is proposed. A simple analysis is given for each resonator. By tuning the geometric parameters of the resonators, the two passbands of the BPF can be adjusted separately. Source‐load coupling is adopted to achieve more transmission zeros in the stopband. The new dual‐band BPF, which has a miniature circuit size of 0.18 × 0.18λg, presents narrow and sharp passband characteristics. Good agreement is found between simulated and measured results, which verify the high‐frequency selectivity.
Miniaturised wideband filtering antenna by employing CRLH‐TL and simplified feeding structure
Authors: Wu Pu‐Chao , Chen Long , Luo Yong‐Lun
Published: March 2015

A miniaturised three‐order wideband ﬁltering antenna by employing a composite right/left handed transmission line (CRLH‐TL) and a simplified asymmetric coplanar strip feeding structure is presented. The CRLH‐TL resonator resonates at zeroth‐order mode and ﬁrst‐positive‐order mode, and the meander‐line antenna performs not only as a radiator but also as the last resonator of the corresponding bandpass filter. The proposed ﬁltering antenna has four poles in the passband and two radiation nulls at the band edges. Compared with conventional antennas, the proposed filtering antenna shows flat gain responses and flat radiated powers within the passband, and displays good frequency skirt selectivity. Measurement results show that the ﬁltering antenna can operate at from 4.03‐ to 7.11 GHz, has a 3.08 GHz bandwidth, a 2.5 dBi average gain in the broadside (+Z) direction and nearly 30 dBm average radiated power within the passband.
Television channel spectrum sensing using independent component analysis
Authors: Ferreira Paulo Ixtanio Leite , Fontgalland Glauco , Albert Bruno Barboso , Gurjão Edmar Candeia
Published: March 2015

Spectrum reuse has been proposed as a method to solve frequency bands scarcity. Detection of unused channels in a given frequency band is the main problem to reuse the spectrum. Various methods are proposed in the literature to perform this spectrum sensing. In this study, the authors apply independent component analysis (ICA) to estimate the available bands in the TV band spectrum when analogue and digital TV channels are in operation. Each component recovered by ICA is in a specific frequency band, then the other bands are considered free to reuse, that is, the absence of transmitters in a channel means there are unused bands. A measurement setup was implemented to validate the use of ICA as a spectrum detection method. The results also show the feasibility of using ICA for wideband spectrum sensing with low computational costs.
On polar multiple description coding
Authors: Valipour Mehrdad , Yousefi Shahram
Published: March 2015

The use of multiple description (MD) provides a reliable communications solution over packet loss channels; the polar source coding takes advantage of reasonable complexities in both the encoder and decoder sides. In this study, a polar MD coding is introduced for the binary input sequence with Hamming distortion in which the central decoder is aided by a common description from the encoder. The algorithm for code construction is studied. The performance evaluation demonstrates the effectiveness of the proposed system for MD with polar coding. In addition, the effects of design parameters have been studied.
Complexity reduced turbo‐bit‐interleaved coded modulation with iterative decoding
Authors: Kang Donghoon , Oh Wangrok
Published: March 2015

Spectral efficiency of turbo code can be improved by use of coded modulation methods such as bit‐interleaved coded modulation (BICM) with iterative decoding (BICM‐ID). On the other hand, the performance of the turbo‐BICM can be further improved by iteratively exchanging information between a decoder and a demodulator within a receiver and this scheme is known as the turbo‐BICM‐ID. Unfortunately, the required complexity of the turbo‐BICM‐ID is much higher than that of the turbo bit‐interleaved coded modulation with iterative decoding turbo‐BICM‐ID. In this study, the authors propose a complexity reduced turbo‐BICM‐ID by optimising the mapping of coded bits to modulation symbols and the amount of information fed back from the decoder to the demodulator.
Secure error‐correcting network codes with side information leakage
Authors: Zhuang Zhuojun , Dai Bin , Luo Yuan , Han Vinck A.J.
Published: March 2015

Incorporating information security and error correction in network coding, which has various applications in communication theory, for example, secret key sharing through a network, is of special interest and has been widely studied. To make a more intensive analysis of secure error‐correcting network codes, we investigate how to secure k source symbols transmission in a multicast network against an adversary that can obtain k1 source symbols as side information, eavesdrop μ channels and contaminate d channels. We introduce relative network generalised Hamming weight (RNGHW) with network error correction (NEC), or briefly NEC‐RNGHW, to measure the equivocation to the adversary. Network generalised singleton bound on NEC‐RNGHW is obtained and code constructions achieving the bound are provided. By these constructions, the maximum rate of a secure linear multicast is n − 2d − μ − k1, where n is the minimum value of the maxflows from a source node to sink nodes. We also characterise the equivocation by the relative profiles of a linear code and a subcode, and tighten the singleton bound on equivocation by the generalised Griesmer bound on relative profiles.
Distributed differential admission control algorithm for delay‐tolerant machine‐to‐machine devices
Authors: Li Xiaohui , Li Dan , Bai Yan
Published: March 2015

Machine‐to‐machine (M2M) is a new type of communication which can be used in e‐health, smart meters and so on. However a huge number of M2M devices will cause access congestion in third generation long‐term evolution systems. It will bring access delays which cannot satisfy the requirements for the M2M deceives, especially for the devices with low tolerant delays. In this study, the authors investigate a distributed differential admission control algorithm that improves the access fairness for M2M devices with different tolerant delays. To maximise the access fairness while maintaining the throughput, an optimisation model is established by formulating a fairness‐throughput payoff function. Then, a parallel and distributed algorithm, namely, Jacobi algorithm, is introduced to solve the optimisation problem. Furthermore, the constraint of the key parameters is given to guarantee that the algorithm can converge to the optimal solution. The simulation results show that the M2M devices with different tolerant delays have the maximum access fairness in their own tolerant delays by using the proposed method.
Analytical characterisation and optimum performance of DC‐biased optical orthogonal frequency division multiplexing signals
Authors: Guerreiro João , Dinis Rui , Montezuma Paulo
Published: March 2015

Orthogonal frequency division multiplexing (OFDM) schemes are being considered for both optical fibre and wireless optical communications mainly because their ability to cope with the high inter‐symbol interference levels associated to dispersive channels. DC biased optical OFDM (DCO‐OFDM) is a promising technique that meet the particularities of intensity modulated OFDM schemes. To reduce the required DC component OFDM signals need to be submitted to an asymmetric clipping. However, the resulting non‐linear distortion effects can lead to significant performance degradation and/or undesirable out‐of‐band radiation. Therefore it is important to evaluate the impact of an asymmetric clipping on DC‐biased optical OFDM signals. In this work, the authors take advantage of the Gaussian‐like nature of OFDM signals and they study analytically the impact of an asymmetric clipping operation in the performance of DCO‐OFDM schemes. The authors present accurate theoretical expressions for the power spectral density and the non‐linear distortion at the subcarrier level, which can be used for obtaining the bit error rate of conventional receivers. The authors also study the optimum performance of these non‐linear OFDM schemes and the authors show that for an optimum maximum likelihood detection the non‐linear distortion instead of leading to performance degradation can actually improve it, even outperforming conventional, linear OFDM schemes.
Performance analysis of multiple‐input multiple‐output interference alignment with user selection
Authors: Lee Donghun , Park Seungkeun
Published: March 2015

The performance analysis of the multiple‐input multiple‐output interference alignment (IA) with user selection in small‐cell interference channels is investigated. In this system, the authors consider the user selection using spatially independent scheduling in which a transmitter sends the data stream of the selected user providing the maximum effective signal‐to‐noise ratio (SNR). As the first step, this study derives exact and approximate probability density functions of the effective SNR of the proposed IA with user selection. Next, exact closed‐form expressions of the bit‐error rate (BER) for the M‐ary quadrature amplitude modulation, M‐ary phase shift keying modulation and outage probability are presented. Using asymptotic analysis, the BER and outage probability of the proposed IA system with user selection are approximated, and the diversity order and SNR gain are quantified, respectively. Also, the authors derive tight closed‐form expression of the proposed system for ergodic capacity using the Taylor series expansion of logarithm function. The analytical results show that diversity order of the IA system with user selection is superior to that of the conventional iterative algorithms. Also, the ergodic capacity of the proposed system is superior to that of the conventional iterative algorithms at high SNR. This performance gain comes from multi‐user diversity. The analytical results are verified through simulation results.
Robust H2 and H∞ filtering for discrete‐time uncertain Linear fractional transform systems
Authors: Sadeghzadeh Arash
Published: March 2015

This study is concerned with the problem of robust H2 and H∞ filtering for uncertain discrete‐time linear systems. Two types of time‐invariant parametric uncertainty, namely polytopic and ellipsoidal, are considered and represented by a linear fractional transformation structure. Obtained auxiliary variables by a convex optimisation problem, play the role of decoupling the Lyapunov variables and the robust filter parameters, in order to cast the problem into a linear matrix inequality‐based optimisation problem. The design conditions are derived based on the quadratic separation concept and employing appropriate parameterisations for the corresponding set of multipliers. The merit of the methods presented in this study lies in their less conservatism than the existing methods for the polytopic uncertain systems, as well as presenting a new convex optimisation procedure for the robust filtering for the ellipsoidal uncertain systems.
Estimation of disparity map of stereo image pairs using spatial domain local Gabor wavelet
Authors: Malathi T. , Bhuyan M.K.
Published: March 2015

The stereo matching problem takes two images captured by nearby cameras and attempts to recover quantitative disparity information. Most of the existing stereo matching algorithms find it difficult to estimate disparity in the occlusion, discontinuities and textureless regions in the images. In the last few decades, a number of stereo matching methods have been proposed to overcome some of these problems. In the same line of thought, the authors propose a new feature‐based stereo matching method, which consists of four basic steps – feature‐based stereo correspondence, two‐pass cost aggregation, disparity computation using winner‐takes‐all selection and finally, the disparity refinement. In the proposed method, local features of Gabor wavelet in spatial domain are used for matching cost computation and subsequently a cost aggregation step is implemented by combined use of the Kuwahara filter and the median filter. Experimental results on the Middlebury benchmark database shows that the proposed method outperforms many existing local stereo matching methods.
Unsupervised discovery of human activities from long‐time videos
Authors: Elloumi Salma , Cosar Serhan , Pusiol Guido , Bremond Francois , Thonnat Monique
Published: March 2015

In this study, the authors propose a complete framework based on a hierarchical activity model to understand and recognise activities of daily living in unstructured scenes. At each particular time of a long‐time video, the framework extracts a set of space‐time trajectory features describing the global position of an observed person and the motion of his/her body parts. Human motion information is gathered in a new feature that the authors call perceptual feature chunks (PFCs). The set of PFCs is used to learn, in an unsupervised way, particular regions of the scene (topology) where the important activities occur. Using topologies and PFCs, the video is broken into a set of small events (‘primitive events’) that have a semantic meaning. The sequences of ‘primitive events’ and topologies are used to construct hierarchical models for activities. The proposed approach has been tested with the medical field application to monitor patients suffering from Alzheimer's and dementia. The authors have compared their approach to their previous study and a rule‐based approach. Experimental results show that the framework achieves better performance than existing works and has the potential to be used as a monitoring tool in medical field applications.
Debates on ultra‐high‐voltage synchronous power grid: the future super grid in China?
Authors: Xu Zheng , Dong Huanfeng , Huang Hongyang
Published: March 2015

This study presents the analysis of debates on the future super grid in China. The rapid increase of power demands and the uneven distribution of energy bases and load demands in China require bulk‐capacity long‐distance power transmission. Two candidate solutions are thus proposed, that is, the ultra‐high‐voltage ac (UHVAC) synchronous power grid and the extra high‐voltage ac (EHVAC) asynchronous super power grid. The debates on the above two power grids are first reviewed. The two candidate power grids are then compared in detail in terms of security, economic and environmental aspects. Finally, this study provides a suggestion for the construction of UHV synchronous power grid in China as well as the future research direction. The research, discussion and conclusion related to UHVAC and EHVAC transmissions in China are expected to provide useful references for power system planning in other countries and to promote the development of the global power industry.
Identifying critical components for reliability centred maintenance management of deregulated power systems
Authors: Ghorani Rahim , Fotuhi‐Firuzabad Mahmud , Dehghanian Payman , Li Wenyuan
Published: March 2015

Competition in the electric power industry urges utilities to not only reduce the investment costs, but also to reasonably cut the operation and maintenance expenses as much as possible, while keeping both power quality and reliability requirements met. Reliability‐centred maintenance (RCM) has been proven to be in response to this dilemma in power systems and has been yet successfully applied in various engineering contexts. This study introduces a novel approach, as of the first steps of RCM implementation in composite power generation and transmission systems, to identify the critical components for the main sake of a more focused maintenance management. Criticality evaluation is, here, concerned with components outage occurrence possibilities and cost‐based consequences. A realistic market model has been implemented to account for the components outage consequences to the system different participants, that is, generation companies and distribution companies. The presented methodology is able to efficiently recognise the individual importance and contribution of each component in the cases of not only first order but also higher order contingencies. For the sake of demonstration, the proposed approach is applied to the IEEE reliability test system and IEEE 118‐Bus test system, and the obtained results are discussed in detail.
Secondary arc current of ultra‐high voltage transmission line with a mixed voltage of 1000/500 kV on a single tower
Authors: Sima Wenxia , Wang Rong , Yang Ming , Yang Qing , Yuan Tao
Published: March 2015

Among the ultra‐high‐voltage (UHV) grids in eastern China, the construction of multi‐circuit transmission lines with mixed voltages on a single tower is a novel transmission technology that can significantly reduce line corridor coverage, maximise the use of tower height and significantly improve power transmission capacity per area. However, the electromagnetic interaction between lines is complicated and interferes with the secondary arc current. This study proposes a hybrid tower model that incorporates double‐circuit transmission lines with alternating currents at 1000 and 500 kV. Its secondary arc current is investigated according to circuit analysis and EMTDC in consideration of the electromagnetic coupling effect, along with the influences of line length, compensation, phase sequence and transposition on the secondary arc current. Results show that a strong secondary arc current is generated for 1000 kV transmission lines in accordance with the UHV hybrid transmission project from Ximeng to Shanghai. This finding should be emphasised. Furthermore, the influence of quadruple‐circuit line length on the secondary arc current depends on line voltage rating. Finally, this study presents several methods that may reduce the secondary arc current, such as transposing lines evenly and installing suitable neutral reactors.
Real time implementation of artificial neural networks‐based controller for battery storage supported wind electric generation
Authors: Kurian Sony , Krishnan Sindhu T. , Cheriyan Elizabeth P.
Published: March 2015

Energy storage systems have established their capability to overcome the problems caused by intermittent nature of renewable sources when integrated to existing grid. Voltage and frequency control, as well as load shifting can be done using grid level storage systems incorporated with renewable sources. They can effectively serve the system as an energy sink and source. Operational use of energy storage for grid level support of a wind electric generator (WEG) is demonstrated in this study. The battery storage supported WEG along with controllers is modelled. Artificial neural network controller, which is having inherent learning capability, is developed to regulate the power flow between wind generator and utility grid. The proposed algorithm and the corresponding controller are simulated in MATLAB/Simulink and implemented in the DSP processor. The real time data exchange between Simulink and the floating point DSP processor TMSF32028335 is realised using on‐board JTAG emulator. The hardware implementation using DSP processor presented in this work establishes the efficacy of the proposed control strategy for real time applications.
Optimal daily scheduling of reconfiguration based on minimisation of the cost of energy losses and switching operations in microgrids
Authors: Nafisi Hamed , Farahani Vahid , Askarian Abyaneh Hossein , Abedi Mehrdad
Published: March 2015

Network reconfiguration has been involved in energy loss reduction by considering the time‐varying nature of loads. Nowadays, with the integration of intermittent micro‐sources (MSs) to the power grid, optimal configuration should be determined corresponding to the variations in loads and generations. In this study, optimum reconfiguration instants are achieved based on the switching operations and energy losses costs. Moreover, the sequence of selecting loops for reconfiguration is optimised in conjunction with the time intervals by a joint optimisation algorithm. Furthermore, a simple branch exchange method of reconfiguration is modified in the presence of MSs. Discrete genetic algorithm (DGA) is employed to optimise the reconfiguration instants as well as the sequence of selecting loops. By applying the proposed method, the total operating cost of the network is reduced significantly, compared to optimum fixed configuration and hourly reconfiguration policies. The proposed algorithm is evaluated on a real‐life 77‐bus distribution system with two interconnected MSs.
Multi‐objective design of advanced power distribution networks using restricted‐population‐based multi‐objective seeker‐optimisation‐algorithm and fuzzy‐operator
Authors: Kumar Deepak , Samantaray Subhransu Ranjan , Kamwa Innocent
Published: March 2015

This study proposes a method for designing advanced power distribution system (PDS) including distributed generations, using a combination of fundamental loop generator and multi‐objective seeker‐optimisation algorithm (MOSOA). The proposed approach reduces the searching space using fundamental loop generator technique to obtain initial feasible solutions which is further improved by SOA to generate new set of solutions with improved aptitude. The proposed methodology uses a contingency‐load‐loss‐index for reliability evaluation, which is independent of the estimation of failure rate and fault repair duration of feeder branches. This planning strategy includes distribution automation devices such as automatic reclosers (RAs) to enhance the reliability of PDS. The proposed algorithm generates a set of non‐dominated solution by simultaneous optimisation of two conflicting objectives (economic cost and system reliability) using Pareto‐optimality‐based trade‐off analysis including a fuzzy‐operation to automatically select the most suitable solution over the Pareto‐front. The performance of the proposed approach is assessed and illustrated on 54‐bus and 100‐bus PDS, considering realtime design practices. Extensive comparisons are made against some well‐known and efficient MO algorithms such as fast non‐dominated sorting genetic algorithm‐II, MO particle‐swarm‐optimisation and MO immunised‐particleswarm‐optimisation. Simulation results show that the proposed approach is accurate and efficient, and a potential candidate for large‐scale PDS planning.
Loss allocation in radial distribution networks with different load models and distributed generations
Authors: Jagtap Kushal Manoharrao , Khatod Dheeraj Kumar
Published: March 2015

Under deregulation and competitive environment, equitable allocation of losses with increasing loads and participation of new generations is a challenging task. This study proposes a solution to loss allocation problem for radial distribution network with various load models and distributed generation (DG). The location, rating and time evolution of the loads and DGs connected to the network are considered in this problem. It traces not only real but also reactive power to identify the actual contribution of loads and DGs into the total network losses. It develops a direct relation between injected current/power of consumers/DGs and network losses. To allocate the fair losses, the proposed method assigns the cross‐terms by employing the geometric scheme of allocation. To show the effectiveness of the proposed method, it has been tested on 33‐node radial network. To validate the proposed method, it has been compared with other methods.
Reliability and sensitivity analysis of composite power systems considering voltage and reactive power constraints
Authors: Benidris Mohammed , Mitra Joydeep
Published: March 2015

This study investigates the effects of voltage and reactive power constraints on composite system reliability indices. Four indices have been used to assess the sensitivity of load curtailments to voltage and reactive power constraints. Furthermore, expressions to evaluate the sensitivity of the severity indices with respect to the voltage and reactive power constraints have been developed. Extensive simulations on the Institute of Electrical and Electronics Engineers (IEEE) reliability test system based on the AC power flow model were carried out to correlate the violations of these limits and the loading level of the system. A non‐linear, AC power flow‐based model has been used to accurately represent system redispatch. A state space reduction technique has been utilised to reduce the computation time. A comparison between redispatch models using AC and DC power flow has been provided to illustrate the benefits of the more accurate AC flow model and to investigate the effects of the voltage and reactive power constraints on reliability indices.
Distance protection of shunt compensated transmission line using a sparse S‐transform
Authors: Dash Pradipta Kishore , Das Sahasransu , Moirangthem Joymala
Published: March 2015

In this study, the detection, classification and location of faults on a power transmission system operating with a Static Compensator (STATCOM). A cumulative sum average technique is used to detect the instant of the occurrence of the fault, while the energy of the important frequency components of the fault current is evaluated using a computationally fast frequency filtering S‐transform (FFST) (sparse ST) to classify the type of fault. Furthermore, the new matrix version of the FFST is used to calculate the fault location, and fault trajectories along with a simplified fast Gauss–Newton algorithm. To validate the new formulation, different types of faults are initiated on a transmission system before and after the STATCOM using MATLAB/SIMULINK software and it is observed from the results that the FFST detects, classifies and locates the fault type accurately in most of the cases. The computational speed of FFST is almost 30 times higher than the conventional discrete ST to make it a likely candidate for real‐time application. Practical verification of the proposed scheme has been attempted using real‐time digital simulator platform.
Rapid design of miniaturised branch‐line couplers through concurrent cell optimisation and surrogate‐assisted fine‐tuning
Authors: Koziel Slawomir , Kurgan Piotr
Published: March 2015

In this study, the authors introduce a methodology for low‐cost simulation‐driven design optimisation of highly miniaturised branch‐line couplers (BLCs). The first stage of their design approach exploits fast concurrent optimisation of geometrically dependent, but electromagnetically isolated cells that constitute a BLC. The cross‐coupling effects between the cells are taken into account in the second stage, where a surrogate‐assisted fine‐tuning procedure is executed. The tuning process is based on space‐mapping‐enhanced low‐fidelity model of the entire BLC. The latter is constructed by cascading local response surface approximations (RSAs) of the BLC building blocks. The efficiency of their technique is demonstrated through the design of two compact BLCs. A considerable scale of miniaturisation has been achieved in both cases (83.7 and 87.4%, respectively), at the computational cost corresponding to a few EM simulations of the respective BLC. Comparison of numerical results with several surrogate‐based design approaches as well as an experimental verification of the final designs are also provided.
Ultra wideband compact near‐field imaging system for breast cancer detection
Authors: Jalilvand Malyhe , Li Xuyang , Zwirello Lukasz , Zwick Thomas
Published: March 2015

In this study, an efficient near‐field imaging system using miniaturised bowtie antennas is proposed for the three‐dimensional (3D) detection of breast tumours. To ensure good penetration and high resolution, a novel compact bowtie antenna is developed. The antenna features a high fractional bandwidth covering both low and high frequencies, while still small in size. A hemispherical array of 16 compact bowtie antennas is built and following a multistatic scenario, scattered signals from two breast phantoms with one and two embedded tumours inside are recorded. The radar‐based set‐up operates in the frequency range of 1.2–7 GHz. It is shown that the imaging system can successfully detect the tumour phantoms in 3D space.
Design and study of nano‐plasmonic couplers using aluminium arsenide and alumina
Authors: Saber Md. Ghulam , Sagor Rakibul Hasan
Published: March 2015

A theoretical study of nano‐plasmonic couplers constructed using aluminium arsenide (AlAs) and alumina (Al2 O3) is presented. The analysis has been done using the finite difference time domain technique. The dependence of coupling efficiency on the width of the air layer of silver–air–silver waveguide has been investigated to determine the optimal width of air. Coupling efficiency with the variation in input signal wavelength, reflection coefficient and return loss have been calculated numerically in order to characterise the performance of AlAs and Al2 O3 as nano‐plasmonic couplers. The resonant peaks have also been obtained for both AlAs and Al2 O3. The couplers provide appreciable performance at 1550 nm wavelength and have simple rectangular shape with no tapering which provides advantage in the fabrication process. It also offers broadband operation.
Q‐switched thulium–ytterbium co‐doped fibre laser using newly developed octagonal shaped inner cladding double‐clad active fibre and multi‐walled carbon nanotubes passive saturable absorber
Authors: Babar I.M. , Sabran M.B.S. , Harun Sulaiman Wadi , Ahmad Harith , Paul M.C. , Halder Arindam , Das Shyamal , Bhadra S.K.
Published: March 2015

Simple and low cost passive Q‐switched thulium–ytterbium co‐doped fibre lasers (TYFL) operating at 1977.5 nm is demonstrated using 905 nm multimode pumping, in conjunction with a multi‐walled carbon nanotubes (MWCNTs) saturable absorber. It uses a new octagonal shaped double‐clad thulium ytterbium co‐doped fibre, manufactured using a modified chemical vapour deposition process and a solution doping. The Tm3+ and Yb3+ cladding absorptions of the fibre are 0.325 and 3.3 dB/m at 790 nm and 976 nm, respectively. The MWCNTs composite is prepared by mixing the MWCNTs homogeneous solution with a diluted polyvinyl alcohol polymer solution before it is left to dry at room temperature to produce thin film. The film is sandwiched between two fibre connectors and integrated into the laser cavity for Q‐switching pulse generation. The repetition rate of the Q‐switching pulse can be tuned from 18.8 to 50.6 kHz while the pulse width reduces from 8.6 to 1.0 µs as the pump power increases from 1.6 to 2.3 W. At the pump power of 2.1 W, the TYFL produces the maximum pulse energy of 5.7 nJ.
Wide‐range in‐fibre Fabry‐Perot resonator for ultrasonic sensing
Authors: Islam Md. Rajibul , Mahmood Ali Muhammad , Lai Man‐Hong , Lim Kok‐Sing , Gunawardena Dinusha Serandi , Machavaram Venkata Rajanikanth , Ahmad Harith
Published: March 2015

This study reports on the demonstration and characterisation of a short cavity fibre Fabry‐Perot resonator (FPR) for the detection of ultrasonic waves propagating through a solid medium over a frequency range of 1 kHz–10 MHz. The proposed sensing device has some outstanding features in terms of simple fabrication technique, frequency response and high sensitivity over a wide frequency range. The response of the surface‐mounted FPR sensor showed good agreement with that of a commercially available piezoelectric transducer during ultrasonic excitation.
Optical data shifting using polarisation properties of light
Authors: Chattopadhyay Tanay
Published: March 2015

Various optical binary data shifting circuits have been designed here by using a polarising beam splitter, a half‐wave plate and liquid crystal‐phase spatial light modulators. These circuits are based on the polarisation properties of light. Here, p‐polarised light (logic value ‘1’) and no light (logic value ‘0’) are considered as optical binary bits. Numerical simulations have been performed to find the insertion loss using the data sheet of some commercially available optical products.
Stacked polymer waveguide type fan‐in/fan‐out device for dense multi‐core fibre
Authors: Watanabe Tatsuhiko , Kokubun Yasuo
Published: March 2015

A compact fan‐in/fan‐out waveguide device for 19‐core uncoupled multi‐core fibre (MCF) was demonstrated using laminated polymer waveguide. The core was made of poly‐methyl‐methacrylate and the cladding was made of ultra‐violet (UV) cured epoxy resin which is solvent‐free oligomer. Since the oligomer does not shrink after UV‐curing, the surface of the cladding over the core ridge was flattened and the multiple layers can be laminated. The accurate core alignment in the vertical direction was realised by controlling the spin‐coat condition of cladding material precisely. The insertion loss from a 19‐core fibre to 19 single‐core fibres was measured to be <20 dB and the sum of the cross‐talk from all neighbouring cores was lower than −40 dB. The coupling loss which is caused by the offset of the core position and the spot size mismatch at the facet between the MCF core and the waveguide was <1.8 dB. It was shown that the coupling loss and the insertion loss can be improved by adopting a properly selected pair of polymer materials with appropriate value of index contrast and low absorption loss.
Low‐frequency dc bus ripple cancellation in single phase pulse‐width modulation inverters
Authors: Mahadeva Iyer Vishnu , John Vinod
Published: March 2015

This study presents a topology for a single‐phase pulse‐width modulation (PWM) converter which achieves low‐frequency ripple reduction in the dc bus even when there are grid frequency variations. A hybrid filter is introduced to absorb the low‐frequency current ripple in the dc bus. The control strategy for the proposed filter does not require the measurement of the dc bus ripple current. The design criteria for selecting the filter components are also presented in this study. The effectiveness of the proposed circuit has been tested and validated experimentally. A smaller dc‐link capacitor is sufficient to keep the low‐frequency bus ripple to an acceptable range in the proposed topology.
Small‐signal model analysis and control design of a double‐ended forward converter in discontinuous‐capacitor‐voltage mode
Authors: Yang Jianbo , Faris Al‐Naemi , Zhang Weiping
Published: March 2015

A double‐ended forward converter with an input inductor–capacitor filter has inherent power factor correction (PFC) properties and continuous input current when operating in discontinuous‐capacitor‐voltage mode (DCVM). In this study, the minimum separable switching configuration modelling is applied to the proposed converter operating in DCVM to obtain a small‐signal model of the converter. The impact of the circuit parameters on the small‐signal characteristic are discussed in details. The difference between the small‐signal behaviour of the converter when operating as a DC/DC converter and a PFC converter is investigated. The modelling methodology is intended for the design of controllers in closed‐loop operation. A 100 W prototype is implemented to demonstrate the feature of the small‐signal behaviour.