bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictive habitat suitability models to aid conservation of elasmobranch diversity in the central Mediterranean Sea
Authors: Lauria V. , Gristina M. , Attrill M. J. , Fiorentino F. , Garofalo G.
Published: August 2015

Commercial fisheries have dramatically impacted elasmobranch populations worldwide. With high capture and bycatch rates, the abundance of many species is rapidly declining and around a quarter of the world’s sharks and rays are threatened with extinction. At a regional scale this negative trend has also been evidenced in the central Mediterranean Sea, where bottom-trawl fisheries have affected the biomass of certain rays (e.g. Raja clavata) and sharks (e.g. Mustelus spp.). Detailed knowledge of elasmobranch habitat requirements is essential for biodiversity conservation and fisheries management, but this is often hampered by a poor understanding of their spatial ecology. Habitat suitability models were used to investigate the habitat preference of nine elasmobranch species and their overall diversity (number of species) in relation to five environmental predictors (i.e. depth, sea surface temperature, surface salinity, slope and rugosity) in the central Mediterranean Sea. Results showed that depth, seafloor morphology and sea surface temperature were the main drivers for elasmobranch habitat suitability. Predictive distribution maps revealed different species-specific patterns of suitable habitat while high assemblage diversity was predicted in deeper offshore waters (400–800 m depth). This study helps to identify priority conservation areas and diversity hot-spots for rare and endangered elasmobranchs in the Mediterranean Sea.
Photonic ququart logic assisted by the cavity-QED system
Authors: Luo Ming-Xing , Deng Yun , Li Hui-Ran , Ma Song-Ya
Published: August 2015

Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions of qubit systems, we investigate the possibility of ququart systems (four-dimensional states) dependent on two DOFs of photon systems. We propose some useful one-parameter four-dimensional quantum transformations for the construction of universal ququart logic gates. The interface between the spin of a photon and an electron spin confined in a quantum dot embedded in a microcavity is applied to build universal ququart logic gates on the photon system with two freedoms. Our elementary controlled-ququart gates cost no more than 8 CNOT gates in a qubit system, which is far less than the 104 CNOT gates required for a general four-qubit logic gate. The ququart logic is also used to generate useful hyperentanglements and hyperentanglement-assisted quantum error-correcting code, which may be available in modern physical technology.
Correction: Cold shock induces apoptosis of dorsal root ganglion neurons plated on infrared windows
Authors: Aboualizadeh Ebrahim , Mattson Eric C. , O'Hara Crystal L. , Smith Amanda K. , Stucky Cheryl L. , Hirschmugl Carol J.
Published: August 2015

Correction for ‘Cold shock induces apoptosis of dorsal root ganglion neurons plated on infrared windows’ by Ebrahim Aboualizadeh et al., Analyst, 2015, 140, 4046–4056.
A crystalline low molecular weight cyclic organoboron compound for efficient solid state lithium ion transport
Authors: Joshi Prerna , Vedarajan Raman , Matsumi Noriyoshi
Published: August 2015

We report the synthesis of a crystalline cyclic organoboron compound that shows an anomalous Li-ion conduction behaviour with specific composition and method of insertion of a Li salt.
Enzyme-responsive pillar[5]arene-based polymer-substituted amphiphiles: synthesis, self-assembly in water, and application in controlled drug release
Authors: Gao Lingyan , Zheng Bo , Chen Wei , Schalley Christoph A.
Published: August 2015

Pillar[5]arene-based PEG-substituted amphiphiles form enzyme-responsive micelles in water useful for drug-delivery.
A computational study of the effect of the metal organic framework environment on the release of chemically stored nitric oxide
Authors: Li Tanping , Taylor-Edinbyrd Kiara , Kumar Revati
Published: August 2015

Computational investigations into the effect of a copper based metal organic framework on the sustained release of NO from S-nitrosothiols.
Vibrational and coherence dynamics of molecules
Authors: Zhang Zhedong , Wang Jin
Published: August 2015

The relaxation of coherence in vibrational energy transport in molecules is investigated.
Can we judge an oxide by its cover? The case of platinum over α-Fe2O3 from first principles
Authors: Neufeld Ofer , Toroker Maytal Caspary
Published: August 2015

Solar water splitting may be improved by reduced charge carrier mass in Fe2O3 covered with Pt.
Different mechanisms at different temperatures for the ring-opening polymerization of lactide catalyzed by binuclear magnesium and zinc alkoxides
Authors: Sun Yangyang , Cui Yaqin , Xiong Jiao , Dai Zhongran , Tang Ning , Wu Jincai
Published: August 2015

Two binuclear magnesium and zinc alkoxides supported by a bis-salalen type dinucleating heptadentate Schiff base ligand can catalyze the ring-opening polymerization of lactide via different mechanisms at different temperatures.
Enantioselective aerobic oxidation of olefins by magnetite nanoparticles at room temperature: a chiral carboxylic acid strategy
Authors: Hadian-Dehkordi Leila , Hosseini-Monfared Hassan
Published: August 2015

Magnetite nanoparticles stabilized by l-(+)-tartaric acid show high to excellent enantioselectivity in the aerobic epoxidation of olefins.
Fabrication and applications of complex-shaped microparticles via microfluidics
Authors: Seo K. D. , Kim D. S. , Sánchez S.
Published: August 2015

There are two notable microfluidics approaches for the synthesis of complex-shaped microparticles, namely droplet based and flow-lithography based microfluidics approaches.
Enhanced photoluminescence properties of red emitting Ba1−xAl2Si2O8:xEu3+ phosphors by charge compensation
Authors: Hakeem Deshmukh Abdul , Park Kyeongsoon
Published: August 2015

The photoluminescence intensities of the Ba1−xAl2Si2O8:xEu3+ phosphors are significantly improved by adding Li, Na or K ions as charge compensators.
Palladium-catalyzed methylene C(sp3)–H arylation of the adamantyl scaffold
Authors: Lao Ye-Xing , Wu Jia-Qiang , Chen Yunyun , Zhang Shang-Shi , Li Qingjiang , Wang Honggen
Published: August 2015

A palladium-catalyzed C(sp3)–H arylation of adamantane at the methylene position with the assistance of an amide group was developed.
A novel electrocatalyst with high sensitivity in detecting glutathione reduced by 2-hydroxypropyl-β-cyclodextrin enveloped 10-methylphenothiazine
Authors: Li Xueni , Zheng Longzhen , Wang Yimin , Zhang Nan , Lou Yan , Xiao Ting , Liu Jiani
Published: August 2015

2-Hydroxypropyl-β-cyclodextrin enveloped the 10-methylphenothiazine catalyst with high sensitivity for the electrochemical detection of reduced glutathione in a neutral environment.
Electronic excitation induced structural, optical and electrical properties of Se85S10Zn5thin films and applicability of a single oscillator model
Authors: Ahmad Shabir , Nasir Mohd. , Asokan K. , Khan Mohd. Shahid , Zulfequar M.
Published: August 2015

The effect of electronic excitation induced by 120 MeV Ag9+ion irradiation on the physical properties of Se85S10Zn5thin films has been investigated at various ion fluencies.
Catalytic performance of bismuth pyromanganate nanocatalyst for Biginelli reactions
Authors: Khademinia Shahin , Behzad Mahdi , Alemi Abdolali , Dolatyari Mahboubeh , Sajjadi S. Maryam
Published: August 2015

Bi2Mn2O7 nano-powders were synthesized via a stoichiometric 1 : 1 Bi : Mn molar ratio hydrothermal method at 180 °C for 48 h in a 1 M NaOH aqueous solution.
A core–shell structured magnetic Ag/AgBr@Fe2O3 composite with enhanced photocatalytic activity for organic pollutant degradation and antibacterium
Authors: Huang Shuquan , Xu Yuanguo , Chen Zhigang , Xie Meng , Xu Hui , He Minqiang , Li Huaming , Zhang Qi
Published: August 2015

A core–shell structured Ag/AgBr@Fe2O3 composite was prepared successfully. It has magnetic properties, highly efficient photocatalytic activity and antibacterial ability.
Confined polymerization: catalyzed synthesis of high Tm, nanofibrous polyethylene within porous polymer microspheres
Authors: Wang Kui , Lei Jinhua , Zhou Guangyuan
Published: August 2015

Linear polyethylene nanofibers are formed through ethylene confined polymerization. Polyethylene nanofibers (<70 nm) are aggregated to form intertwined thicker fibers (300 nm to 22 μm). The obtained PE has a high Mw and Tm2 (up to 142.4 °C).
Mg–Fe mixed oxides as solid base catalysts for the transesterification of microalgae oil
Authors: Xu Sheng , Zeng Hong-Yan , Cheng Chao-Rong , Duan Heng-Zhi , Han Jing , Ding Peng-Xuan , Xiao Gao-Fei
Published: August 2015

Mg–Fe LDO with different Mg/Fe molar ratios as catalysts were adopted for transesterification of microalgae oil, and the catalytic performance of the catalysts was closely related to their basicity and crystallinity.
A porous trimetallic Au@Pd@Ru nanoparticle system: synthesis, characterisation and efficient dye degradation and removal
Authors: Sahoo Anupam , Tripathy Suman Kumar , Dehury Niranjan , Patra Srikanta
Published: August 2015

Treatment of azo dye-based waste water using new trimetallic porous Au@Pd@RuNPs and solid waste dolochar is described.
Mechanically robust glucose strutted graphene aerogel paper as a flexible electrode
Authors: Lee Wee Siang Vincent , Peng Erwin , Choy Dian Chun , Xue Jun Min
Published: August 2015

With the advent of next generation wearable technologies, energy storage devices at present not only have to achieve high energy densities, they also need to possess reasonable mechanical robustness.
Simple and low-temperature polyaniline-based flexible ammonia sensor: a step towards laboratory synthesis to economical device design
Authors: Bandgar D. K. , Navale S. T. , Nalage S. R. , Mane R. S. , Stadler F. J. , Aswal D. K. , Gupta S. K. , Patil V. B.
Published: August 2015

The flexible PAni ammonia sensor not only exhibits high sensitivity, good selectivity and a fast response but also has flexibility, cheap with wearable characteristics.
Arylsilanes and siloxanes as optoelectronic materials for organic light-emitting diodes (OLEDs)
Authors: Sun Dianming , Ren Zhongjie , Bryce Martin R. , Yan Shouke
Published: August 2015

Arylsilanes and siloxanes have been extensively studied as components of OLEDs. In this review, we summarize the recent advances in the utilization of arylsilanes and siloxanes as fluorophore emitters, hosts for phosphor emitters, hole and exciton blocking materials, and as electron and hole transporting materials.
Efficient entry of cell-penetrating peptide nona-arginine into adherent cells involves a transient increase in intracellular calcium
Authors: Melikov Kamran , Hara Ann , Yamoah Kwabena , Zaitseva Elena , Zaitsev Eugene , Chernomordik Leonid V.
Published: August 2015

Understanding the mechanism of entry of cationic peptides such as nona-arginine (R9) into cells remains an important challenge to their use as efficient drug-delivery vehicles. At nanomolar to low micromolar R9 concentrations and at physiological temperature, peptide entry involves endocytosis. In contrast, at a concentration ≥10 μM, R9 induces a very effective non-endocytic entry pathway specific for cationic peptides. We found that a similar entry pathway is induced at 1–2 μM concentrations of R9 if peptide application is accompanied by a rapid temperature drop to 15°C. Both at physiological and at sub-physiological temperatures, this entry mechanism was inhibited by depletion of the intracellular ATP pool. Intriguingly, we found that R9 at 10–20 μM and 37°C induces repetitive spikes in intracellular Ca2+ concentration. This Ca2+ signalling correlated with the efficiency of the peptide entry. Pre-loading cells with the Ca2+ chelator BAPTA (1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid) inhibited both Ca2+ spikes and peptide entry, suggesting that an increase in intracellular Ca2+ precedes and is required for peptide entry. One of the hallmarks of Ca2+ signalling is a transient cell-surface exposure of phosphatidylserine (PS), a lipid normally residing only in the inner leaflet of the plasma membrane. Blocking the accessible PS with the PS-binding domain of lactadherin strongly inhibited non-endocytic R9 entry, suggesting the importance of PS externalization in this process. To conclude, we uncovered a novel mechanistic link between calcium signalling and entry of cationic peptides. This finding will enhance our understanding of the properties of plasma membrane and guide development of future drug-delivery vehicles.
Amyloid fibrils are the molecular trigger of inflammation in Parkinson's disease
Authors: Gustot Adelin , Gallea José Ignacio , Sarroukh Rabia , Celej María Soledad , Ruysschaert Jean-Marie , Raussens Vincent
Published: August 2015

Parkinson's disease (PD) is an age-related movement disorder characterized by a progressive degeneration of dopaminergic neurons in the midbrain. Although the presence of amyloid deposits of α-synuclein (α-syn) is the main pathological feature, PD brains also present a severe permanent inflammation, which largely contributes to neuropathology. Although α-syn has recently been implicated in this process, the molecular mechanisms underlying neuroinflammation remain unknown. In the present study, we investigated the ability of different α-syn aggregates to trigger inflammatory responses. We showed that α-syn induced inflammation through activation of Toll-like receptor 2 (TLR2) and the nucleotide oligomerization domain-like receptor pyrin domain containing 3 (NLRP3) inflammasome only when folded as amyloid fibrils. Oligomeric species, thought to be the primary species responsible for the disease, were surprisingly unable to trigger the same cascades. As neuroinflammation is a key player in PD pathology, these results put fibrils back to the fore and rekindles discussions about the primary toxic species contributing to the disease. Our data also suggest that the inflammatory properties of α-syn fibrils are linked to their intrinsic structure, most probably to their cross-β structure. Since fibrils of other amyloids induce similar immunological responses, we propose that the canonical fibril-specific cross-β structure represents a new generic motif recognized by the innate immune system.
Containment control of linear multi‐agent systems with directed graphs and multiple leaders of time‐varying bounded inputs
Authors: Zhou Feng , Wang Zhengjie
Published: August 2015

This study addresses containment control problem for multi‐agent systems with general linear dynamics. The main contribution of this study is to solve the containment control problem with multiple leaders whose control inputs might be non‐zero, time varying, and the interaction graph among the followers is directed. On the basis of the neighbouring state information, a distributed static containment controller is designed, the containment error asymptotically converges to zero if the subgraph associated with the followers is directed and at least one leader has a directed path to each follower. Then, an observer‐based adaptive containment controller is proposed without knowing any global information about the topology, especially the eigenvalues of the Laplacian matrix. Simulations indicate the capabilities of the algorithm.
Output‐feedback proportional–integral– derivative‐type control with simple tuning for the global regulation of robot manipulators with input constraints
Authors: Mendoza Marco , Zavala‐Río Arturo , Santibáñez Víctor , Reyes Fernando
Published: August 2015

An output‐feedback proportional–integral‐derivative‐type control scheme for the global position stabilisation of robot manipulators with bounded inputs is proposed. It guarantees the global regulation objective avoiding input saturation by releasing the feedback not only from the exact knowledge of the system structure and parameter values, but also from velocity measurements. With respect to previous approaches of the kind, the proposed scheme remains simple while increasing design/performance‐adjustment flexibility. For instance, it does not impose the use of a specific sigmoidal function to achieve the required boundedness but involves a generalised type of saturation functions. More importantly, it is characterised by a very simple control‐gain tuning criterion, the simplest hitherto obtained in the considered analytical context. Experimental tests on a 2‐degree‐of‐freedom direct‐drive manipulator corroborate the efficiency of the developed scheme.
Identification of two‐input two‐output process using state‐space analysis
Authors: Nema Swapnil , Padhy Prabin Kumar
Published: August 2015

An analytical expression for the exact identification of two‐input two‐output (TITO) process using hysteresis relay is presented in this study. The identified transfer matrix consists of four independent first‐order plus delay time (FOPDT) models and the time constants, delays and the gains of the FOPDT models are obtained from the limit cycle measurements. In this study, analytical expressions are derived using state‐space analysis to identify the exact transfer matrix of the TITO process (TITO system). Problem of chattering and measurement noise is attenuated using relay with hysteresis. The simulation examples and real‐time experiment show the effectiveness of the proposed method.
State‐input constrained asymptotic null‐controllability by a set‐valued approach
Authors: Boujallal Lahoucine , Kassara Khalid
Published: August 2015

This study presents a unified approach to investigate asymptotic null‐controllability under possibly mixed constraints on state and control, for standard ordinary differential equation control systems. Using tools from set‐valued analysis and viability theory, initial data which can be steered to the origin at infinity are provided through a new type of Lyapunov functions. The corresponding controls are given via selections of adequately designed multifunctions, which are examined in both cases of convex constraints and the class of affine‐control systems. Finally, numerical examples from classical mechanics are given to verify the theoretical results.
Iterative learning control design method for linear discrete‐time uncertain systems with iteratively periodic factors
Authors: Zhu Qiao , Hu Guang‐Da , Liu Wei‐Qun
Published: August 2015

In this study, a two‐dimensional (2D) H∞ ‐based method is presented for the iterative learning control (ILC) design problem of a class of linear discrete‐time systems with iteratively periodic factors, including initial states, parametric uncertainties, disturbances, measurement noises, and reference trajectories. First, the ILC design problem of the linear systems is described as a controller design problem of 2D uncertain Roesser models. Second, the H∞ performance of 2D Roesser models is studied under a general boundary condition. Third, an ILC design criterion is presented to achieve the perfect tracking and specified H∞ performance by using linear matrix inequality approaches. Finally, a numerical example is given to illustrate the efficiency of the proposed ILC design method.
Improved mixed‐delay‐dependent asymptotic stability criteria for neutral systems
Authors: Ding Liming , He Yong , Wu Min , Ning Chongyang
Published: August 2015

This study concerns the problem of asymptotic stability analysis for neutral systems with mixed delays. Some simple and less conservative criteria are firstly proposed based on the Wirtinger‐based integral inequality. Then, incorporating the delay‐decomposition idea with the augmented Lyapunov–Krasovskii functional, a new augmented delay‐decomposition Lyapunov–Krasovskii functional is constructed. In addition, the Wirtinger‐based integral inequality is sufficiently utilised to cope with the derivative of the constructed functional. Those treatments lead to less conservatism, and an improved asymptotic stability condition is obtained. Finally, a numerical example is given to show the effectiveness and benefit of the proposed criteria.
H∞ filtering for a class of singular biological systems
Authors: Zhao Feng , Zhang Qingling , Zhang Yi
Published: August 2015

This study deals with the H∞ filtering problem for a class of singular biological systems with stochastic exogenous disturbance. Singular system theory is utilised to build a stochastic singular food chain system. The authors’ purpose is to estimate the unmeasurable state variables of the food chain system by the available measurements. The general condition is established for a class of non‐linear singular systems to achieve input‐to‐state stable in mean and the prescribed H∞ performance level. A sufficient condition of the solvability of filtering problem is proposed for the singular food chain system. Simulation example is provided to illustrate the effectiveness of the proposed filtering approach developed in this study.
Multi‐objective transmission reinforcement planning approach for analysing future energy scenarios in the Great Britain network
Authors: Barnacle Malcolm , Galloway Stuart , Elders Ian , Ault Graham
Published: August 2015

A multi‐objective transmission reinforcement planning framework has been designed to evaluate the effect of applying a future energy scenario to the Great Britain transmission network. This is achieved by examining the identified non‐dominated set of transmission reinforcement plans, which alleviate thermal capacity constraints, for the multi‐criteria problem of five objectives: investment cost, annual constraint cost saving, annual incremental operation and maintenance cost, outage cost and annual line loss saving. The framework is flexible and utilises a systematic algorithm to generate reinforcement plans and alter the associated reinforcements should they exacerbate thermal constraints; hence a pre‐determined set of reinforcements is not required to evaluate a scenario. The reinforcements considered are line addition (single circuit and double circuit) and line upgrading through reconductoring. The Strength Pareto Evolutionary Algorithm 2 is utilised to explore varying locations, configurations and capacities of network reinforcement. The solutions produced achieve similar cost savings to solutions created by the transmission network owners, showing the suitability of the approach to provide a useful trade‐off analysis of the objectives and to assess the network‐related thermal and economic impact of future energy scenarios. Here, the framework is applied to the 2020 generation mix of the Gone Green scenario developed by National Grid.
Probabilistic harmonic load flow using fast point estimate method
Authors: Mohammadi Mohammad
Published: August 2015

Harmonics originated by non‐linear elements connected to power systems cause unwanted harmful technical problems. In this study a novel probabilistic harmonic load flow based on a point estimate method has been proposed. The proposed method surpasses the previous point estimate methods (PEMs) when generalising the approach to multiple random variables with various probabilistic distributions. Addressing the results of the Monte Carlo simulation (MCS) method as reference, the fast PEM has been applied to a modified version of the IEEE 14 bus test system and the advantages of this new method are highlighted. The results reveal less computational burden and time compared with the MCS method while the accuracy remains at a high level.
Unity power factor operation and neutral current compensation of diesel generator set feeding three‐phase four‐wire loads
Authors: Niwas Ram , Singh Bhim , Goel Sagar , Jain Chinmay
Published: August 2015

This study deals with power quality improvement in a diesel generator (DG) set‐based standalone supply system feeding three‐phase four‐wire(3P4W) loads. The proposed system consists of a diesel engine, three‐phase wound field synchronous generator, a four‐leg voltage source converter (VSC) and3P4W loads. The four‐leg VSC with a capacitor connected on its DC link is used for neutral current compensation and unity power factor operation of the DG set. In addition, the VSC provides harmonics elimination and the load balancing. The voltage of the DG system is controlled by excitation control of the synchronous generator and the frequency is controlled by speed regulating system of the diesel engine. The speed of the engine is regulated by controlling the fuel injection of the diesel engine. An adaptive theory‐based notch filter algorithm is used to extract fundamental component of the load currents for estimation of reference source currents.
Fault current limiter‐battery energy storage system for the doubly‐fed induction generator: analysis and experimental verification
Authors: Guo Wenyong , Xiao Liye , Dai Shaotao
Published: August 2015

Weak low voltage ride‐through (LVRT) ability and unstable output power are two major problems faced by the doubly‐fed induction generator (DFIG). To solve these two problems simultaneously, a commercially available fault current limiter‐battery energy storage system (FCL–BESS), which is suitable to be applied in a microgrid, is proposed in this study. During normal operation, the FCL–BESS stabilises the output power of DFIG by compensating the fluctuating component of DFIG output power with energy buffering capability provided by the battery energy storage system (BESS). On occurrence of a grid fault, the FCL–BESS enhances the LVRT ability of DFIG by inserting the fault current limiting inductor into the stator, which weakens the rotor back electromagnetic force voltage and limits the rotor overcurrent. The FCL–BESS also stabilises the DC‐link voltage by the BESS, which further strengthens the controllability of grid‐side converter and rotor‐side converter. Moreover, the FCL–BESS is able to help grid voltage recover fast and smoothly by providing power support to the grid. Experiments under different conditions have been carried out with a 2 kW prototype to evaluate the performance of the proposed FCL–BESS. Experimental results show that the FCL–BESS have much better performance than using single fault current limiter or BESS and can solve the two problems faced by the DFIG simultaneously and effectively.
Model‐based tuning approach for multi‐band power system stabilisers PSS4B using an improved modal performance index
Authors: Rimorov Dmitry , Kamwa Innocent , Joós Géza
Published: August 2015

Multi‐band power system stabilisers (MB‐PSSs) PSS4B (IEEE standard 421.5‐2005) are advanced power system damping controllers that have evident advantages over conventional PSSs in damping low‐frequency oscillatory modes. However, finding optimal settings for such controllers is challenging due to the increased complexity of the PSS4B structure. This study describes a methodology for MB‐PSS parameter optimisation based on an improved modal performance index as a measure of the controller's stabilising effect. The tuning problem is formulated as a non‐linear constrained optimisation search method: proposed modal performance index is chosen as an objective function to be minimised, while properly selected constraints ensure stability of the closed‐loop system and robustness of the proposed design. The methodology is demonstrated on a benchmark system that is based on an existing network. Comparative analysis between the MB‐PSSs with optimised settings and speed‐based PSS1A‐type stabilisers designed using the conventional methods show the practicality and effectiveness of the proposed methodology. The implemented approach has an advantage of being scalable and suitable for the model‐based tuning of feedback controller of general structure. Additionally, several performance metrics and non‐linear simulations in the ElectroMagnetic Transient Program (EMTP) software confirm superior characteristics of PSS4B.
New findings on bypass damping filter in increasing subsynchronous resonance damping of series compensated system
Authors: Wang Shijia , Xu Zheng , Wang Shen
Published: August 2015

Subsynchronous resonance (SSR) has three categories, namely induction generator effect, torsional interaction and torque amplification. Bypass damping filter (BDF) was generally considered particularly effective for the induction generator effect. In this study, it is shown that BDF is also an effective countermeasure for torsional interaction and transient torque amplification. In addition, it can help reduce transient overvoltage of the series capacitor in a series compensated system. The parameter tuning method for BDF is proposed, based on electrical damping analysis and criterion for torsional stability. The SSR damping effectiveness of BDF in a series compensated system is verified by electrical damping analysis, torsional mode analysis and time‐domain simulation.
Digital filter for phasor estimation applied to distance relays
Authors: Zamora Alejandro , Ramirez Juan M. , Arrieta Paternina Mario R. , Vazquez‐Martinez Ernesto
Published: August 2015

The transient response of the digital filter for relaying purposes has been improved by means of the Taylor–Kalman–Fourier (TKF) filter. This filter is focused on a dynamic phasor, which is adapted to the transient operating conditions and is based on a signal model that is approximated by the Kth Taylor polynomial. This model is extended to the Kalman and Fourier subspaces in order to provide instantaneous estimates through its recursive property. The TKF renders instantaneous phasor estimates at each sample and enhances the impedance estimation under fault conditions. This fact and the results demonstrate the applicability of the proposition for distance relays.
Kalman filter based incipient fault detection method for underground cables
Authors: Ghanbari Teymoor
Published: August 2015

An incipient and self‐clearing arcing fault can be utilised as a precursor of an imminent permanent failure for monitoring of underground cables. Due to very short duration of the incipient faults, generally they cannot be detected by conventional protection relays. This study presents a new method for detection of incipient cable failures by using measured current and voltage at one end of the cable. The incipient faults are detected using an innovation signal calculated from the measured fault current via a Kalman filter. Upon change detection by the innovation signal, the change is checked for discriminating possible incipient fault from other similar conditions. The proposed method is evaluated using several simulations and field data collected from a real network. The results confirm that the method can achieve high accuracy and speed for detection of cables incipient faults.
Unsynchronised fault‐location technique for three‐terminal lines
Authors: Mahamedi Behnam , Sanaye‐Pasand Majid , Azizi Sadegh , Zhu Jian Guo
Published: August 2015

This study describes a new fault‐location technique using negative‐sequence voltage for three‐terminal lines. The ratios between the negative‐sequence voltage magnitudes measured at each terminal are utilised to first determine the faulted section and then to estimate the exact fault location within the section. Since the current data is not deployed, the influence of inherent errors of current transformers can be avoided. The proposed method can accurately locate the unbalanced faults, that is, single‐phase‐to‐ground, double‐phase‐to‐ground, and phase‐to‐phase faults, regardless of the fault resistance and pre‐fault conditions and without any need to identify the fault type. The method requires only the negative‐sequence reactance behind each terminal which can be estimated by the short‐circuit analysis with an acceptable accuracy. Reliability and practicality of the proposed method make it an attractive option to include in numerical protective relays. Simulation experiments with different fault cases reveal the capability of the proposed method.
Adaptive directional overcurrent relay coordination using ant colony optimisation
Authors: Shih Meng Yen , Castillo Salazar Carlos Alberto , Conde Enríquez Arturo
Published: August 2015

The coordination of directional overcurrent relays is most commonly studied based on a fixed network topology within an interconnected power system. Due to its complexity and non‐linearity, the relay coordination is formulated as an optimisation problem. Distribution systems often suffer consequences due to the dynamic changes of network topology and operation of elements. Such changes are for example the inputs and outputs of generators, lines and loads. The consequences are reduction of sensitivity and selectivity of relays. The principal objective of this study is to coordinate the directional overcurrent relays based on adaptive protection scheme. The secondary objective is to present the formulation of ant colony algorithm and a comparison of it with the genetic algorithm.
Dynamic equivalencing of an active distribution network for large‐scale power system frequency stability studies
Authors: Golpîra Hêmin , Seifi Hossein , Haghifam Mahmoud Reza
Published: August 2015

This study presents an approach for developing the dynamic equivalent model of an active distribution network (ADN), consisting of several micro‐grids, for frequency stability studies. The proposed grey‐box equivalent model relies on Prony analysis to establish stop time and load damping as the required modelling parameters. Support vector clustering (SVC) and grouping procedure are employed for aggregation and order‐reduction of ADN. This significantly decreases the sensitivity of the estimated parameters to operating point changes which, in turn, guarantees the model robustness. This is done through representing the SVC output, that is, clusters, by cluster substitutes. The final ADN dynamic equivalent model is represented by several groups, in which their mutual interactions are taken into account by a new developed mathematical‐based criterion. Simulation results reveal that the proposed model is robust which could successfully take into account the continuous and discontinuous uncertainties.
Two‐element Egyptian axe dipole arrays emphasising their wideband and end‐fire radiation performance
Authors: Tang Ming‐Chun , Ziolkowski Richard W.
Published: August 2015

Combinations of two metamaterial‐inspired electrically small antennas are investigated numerically to achieve high directivity and enhanced bandwidth operation near 300 MHz. Two Egyptian axe dipole (EAD) antennas, one active and one passive, are arranged in an end‐fire array configuration. The elements are designed to optimise the out‐of‐phase current distribution of the parasitic element to achieve enhanced directivity performance characteristics, including a peak gain >4.5 dB, front‐to‐back ratio >15 dB, and radiation efficiency >74% over a 3.73 MHz frequency range centred at 312.9 MHz when the separation distance between the elements is ∼0.04λres and the total electrical size of the array is ka = 0.43. By simply increasing the width of both EAD parasitic elements, the array's end‐fire characteristics are transformed into a configuration that has more than a six times increase of the impedance bandwidth. A frequency‐agile version of the array is obtained by incorporating a varactor between the two EAD parasitic elements. The simulation studies indicate that this frequency‐agile, electrically small, end‐fire array provides a much wider effective impedance bandwidth with improved end‐fire radiation characteristics.
Synthesis scheme for wideband filters consisting of three‐coupled‐lines including the cross‐coupling between non‐adjacent lines
Authors: Chen Chun‐Ping , Kato Noriki , Anada Tetsuo
Published: August 2015

To accurately design wideband filters composed of three‐coupled‐lines, an improved equivalent circuit is derived by taking the cross‐coupling between non‐adjacent lines into consideration. Since the cross‐coupling between non‐adjacent lines is also dependent on the coupling between adjacent lines, conventional synthesis techniques cannot be used directly. Instead, an improved synthesis scheme based on successive iterations is proposed to synthesise the filters. As examples, two 2‐stage microstrip three‐coupled‐line filters [bandwidth: 2.67–5.33 GHz (fractional bandwidth: 67%)] with a reversed connection sequence are synthesised, simulated, and experimentally realised to validate the proposed theory. The frequency responses of the designed filters using the authors’ new model and synthesis theory compare well with those by simulation and experiment, whereas an error of about 17% is found in bandwidth if the authors use the conventional model that neglecting the cross‐coupling between non‐adjacent lines. In addition, the asymmetric property of the three‐line unit is revealed.
Micromachined terahertz Fabry–Perot cavity highly directive antennas
Authors: Konstantinidis Konstantinos , Feresidis Alexandros P. , Tian Yingtao , Shang Xiaobang , Lancaster Michael J.
Published: August 2015

The authors present the design and implementation of a new type of micromachined terahertz planar highly directive antenna based on a periodic partially reflective surface. The periodic surface and antenna are fabricated using SU‐8 photoresist micromachining technology. The proposed antenna is based on a Fabry–Perot type resonant cavity which is formed by superimposing the periodic surface over a single waveguide‐fed slot in a metallic ground at a distance of about half wavelength. Simulations and measurements of the antenna performance are presented.
Wide‐angle broadband microwave metamaterial absorber with octave bandwidth
Authors: Bhattacharyya Somak , Ghosh Saptarshi , Chaurasiya Devkinandan , Srivastava Kumar Vaibhav
Published: August 2015

In this study, a broadband metamaterial absorber is presented with octave bandwidth for practical applications. The unit‐cell of proposed absorber structure consists of simple geometrical patches placed diagonally on the top surface of the structure. The proposed structure exhibits broadband absorption response of 8.30 GHz from 6.86 to 15.16 GHz covering the entire X‐band with more than 90% absorptivity. Three distinct absorption peaks at 7.24, 10.18 and 14.32 GHz have been observed in the absorption spectra. The roles of the geometrical parameters have been investigated to explain the principle of absorption. The structure is studied under oblique incidence for both transverse electric and transverse magnetic polarisations, where the broadband response holds good up to 45° incident angles in both the cases. Owing to the two‐fold symmetry, the structure is sensitive to polarisation of the incident field exhibiting maximum absorption at 0° and 90° with no absorption taking place at 45° angle of polarisation. The structure is fabricated and the experimental results are in good agreement with the simulated responses. The proposed structure is very thin (∼λ/8.5 with respect to the centre frequency of the bandwidth) compared with the commercially available microwave absorbers.
Analysis of the radiowave propagation in an underground mine based on the modified Ray launching method
Authors: Kubal Slawomir , Staniec Kamil , Zieliński Ryszard J.
Published: August 2015

The study presents the developed model of electromagnetic wave scattering occurring on the irregular surfaces. This model was implemented in the Ray launching (RL) method. Based on the modified RL, the analysis of electromagnetic wave propagation in an underground mine was performed. The results of theoretical analyses were compared with the results of measurements (from a copper mine) to determine the degree improvement in the electromagnetic field prediction accuracy after the developed model application.
Transparent microstrip patch antenna based on fluorine‐doped tin oxide deposited by spray pyrolysis technique
Authors: Sheikh Shahin , Shokooh‐Saremi Mehrdad , Bagheri‐Mohagheghi Mohammad‐Mehdi
Published: August 2015

Transparent microstrip antenna with fluorine‐doped tin oxide (FTO or SnO2:F) patch is studied here. The authors make use of spray pyrolysis technique to deposit FTO transparent patch on a Pyrex glass substrate. The deposited FTO patches show high optical transmittance (about 80–90%) and low electrical surface resistance (as low as 7 Ω/□). Two transparent microstrip patch antennas (with conventional conductor as ground plane), which are fed by proximity coupling at 2.5 and 5 GHz resonance frequencies, are fabricated and their radiation properties are presented and compared with copper patch antenna counterparts. In order to reduce the conductor loss of the antenna and ameliorate antenna efficiency, thick substrates should be used. The 2.5 GHz antenna shows low efficiency and significant loss in transparent layer but the 5 GHz one shows 3.63 dBi maximum gain and only ∼0.83 dB degradation in comparison with the copper patch antenna.
Comparison between thin‐film solar cells and copper–indium–gallium–diselenide in Southeast Asia
Authors: Md Yunus Nurul Amziah , Nik Aman Nik Hasniza , Khoshsirat Nima
Published: August 2015

This study gives a selective overview of the technological status and comparison of selected thin‐film solar cells. In the first part of this study, the development of thin‐film solar cells is assessed, followed by comparison of the design structure among those thin‐film solar cells and the current status of thin‐film solar cells efficiency. The advantages and disadvantages of thin‐film solar cells are also discussed. In the second part of this study, a comprehensive review is done on research upon copper–indium–gallium–diselenide (CIGS) thin‐film solar cell in Southeast Asia countries. As compared with other regions of the world, Southeast Asia has not started the large manufacturing of CIGS yet, however, the research on it has been started.
Estimating and calibrating the response of multiple wideband digital radio frequency memories in a hardware‐in‐the‐loop system using shuffled frog leaping algorithm
Authors: Huang Hao , Pan Minghai , Gong Shufeng
Published: August 2015

The frequency response of digital radio frequency memory (DRFM) kernel varies over frequency in its passband. This in turn causes distortion to the regenerated radar signal. For wide band DRFMs, this distortion can become more severe and is thus a problem to be solved. For a wide band DRFM kernel, the total magnitude variation in the passband can reach 8 dB. A novel method to estimate and compensate for the distortion is presented in this study. Data recorded during loop‐back testing is used to estimate the response of the DRFM kernel. A digital finite impulse response filter with complex coefficients is then designed and optimised to compensate for this distortion using the shuffled frog leaping algorithm (SFLA), which is a specific implementation of the memetic algorithm. Simulation results demonstrate that, compared with inverse Fourier‐based techniques and genetic algorithm (GA), the SFLA shows an improvement of 0.5 dB in magnitude ripple and 5.7° in phase ripple. The SFLA technique produces usable solutions for length 17 filters, whereas the GA requires filter lengths of more than 30 to reach the same performance. The shorter filters reduce the delay through the DRFM kernel, which is an important design specification in such systems.
Non‐rigid synthetic aperture radar image registration by combining point‐wise background regional similarity and local spatial constraint
Authors: Fan Jianwei , Wu Yan , Zhang Qingjun , Wang Fan , Li Ming
Published: August 2015

Non‐rigid image registration is an important preprocessing step in synthetic aperture radar (SAR) image applications. A crucial problem that involves in it is to reliably establish the correspondences between the feature points extracted from both the reference and sensed image. In this Letter, a non‐rigid registration method is proposed to align two SAR images by registering two sets of feature points extracted from the images. In the proposed method, both point‐wise background regional similarity and local spatial constraint are utilised to find correct correspondences between two feature point sets. Point‐wise background regional similarity is introduced to enhance feature points similarity measurement. Meanwhile, based on the adjacent spatial relationship between feature point and its neighbouring points, a new concept of local spatial constraint is further proposed to robustly characterise the geometric consistency between them, which is designed to reduce the ambiguous matches aroused by speckle noise and feature outliers. By combining these two improvements, the authors generate a new matching cost function and formulate non‐rigid image registration as a correspondence optimisation problem, which can be solved by the probabilistic relaxation method. Experimental results on both simulated and real deformed SAR images indicate the robustness and effectiveness of the proposed method.
Analysis of target multipaths in WiFi‐based passive radars
Authors: Mazhar Haroon , Hassan Syed Ali
Published: August 2015

In this study, the authors investigate the effects on the range measurement accuracy of a WiFi‐based passive radar when multiple copies of signal, from the same target, are received due to propagation through a rich‐scattering environment. These multipath returns from stationary scatters induced range measurement inaccuracies in passive radars including offset of the target from its true range, smearing of the target in range dimension or appearance of ghost targets. Relationship between range measurement inaccuracies due to target multipaths and range resolution of transmission waveform has been studied. A two‐step solution, that is, signal separation followed by equalisation, is also proposed to mitigate the effects of multipaths in WiFi‐based passive radars.
Separation and reconstruction of the rigid body and micro‐Doppler signal in ISAR part I – theory
Authors: Stanković Ljubisa , Stanković Srdjan , Thayaparan Thayananthan , Daković Milos , Orović Irena
Published: August 2015

In radar imaging, the micro‐Doppler effect is caused by fast movements of some scattering points on the target. These movements correspond to highly non‐stationary components in the time–frequency domain of the signal. The rigid body can be considered as stationary at one range location during the processing time. This property is used to separate the micro‐Doppler signal from the rigid body using the L‐statistics. Since the rigid body can be considered as a sparse signal, its values can be fully recovered at the positions where the micro‐Doppler and rigid body components overlap. The recovery is based on the compressive sensing theory and methods. After an overview of the methods, a quantitative analysis of the improvements achieved in the time–frequency‐based separation is done. Moreover, a comparison with both the time and the frequency domain analysis is provided. Analysis of small additive noise influence to the reconstruction accuracy is done.
Separation and reconstruction of the rigid body and micro‐Doppler signal in ISAR part II – statistical analysis
Authors: Stanković Ljubisa , Stanković Srdjan , Thayaparan Thayananthan , Daković Milos , Orović Irena
Published: August 2015

Micro‐Doppler effect corresponds to non‐stationary components in the time–frequency domain, while the rigid body can be considered as a stationary signal during the processing time. This property is used in the first part of the study to present the method for separation recovery based on the compressive sensing theory. Recovery bounds are based on the restricted isometry property or the coherence and spark analysis. Their calculation is a computationally difficult (Non‐deterministic Polynomial‐time (NP) hard) problem. These bounds also produce very pessimistic results. It is the reason to consider the statistical analysis of the reconstruction results. The statistical approach is presented in this part of the study and illustrated by examples, including a detailed case study example.