bluuebunny/crossref_metadata_2025 huggingface dataset:
Toward 10 meV Electron Energy-Loss Spectroscopy Resolution for Plasmonics
Authors: Bellido Edson P. , Rossouw David , Botton Gianluigi A.
Published: April 2014

Energy resolution is one of the most important parameters in electron energy-loss spectroscopy. This is especially true for measurement of surface plasmon resonances, where high-energy resolution is crucial for resolving individual resonance peaks, in particular close to the zero-loss peak. In this work, we improve the energy resolution of electron energy-loss spectra of surface plasmon resonances, acquired with a monochromated beam in a scanning transmission electron microscope, by the use of the Richardson–Lucy deconvolution algorithm. We test the performance of the algorithm in a simulated spectrum and then apply it to experimental energy-loss spectra of a lithographically patterned silver nanorod. By reduction of the point spread function of the spectrum, we are able to identify low-energy surface plasmon peaks in spectra, more localized features, and higher contrast in surface plasmon energy-filtered maps. Thanks to the combination of a monochromated beam and the Richardson–Lucy algorithm, we improve the effective resolution down to 30 meV, and evidence of success up to 10 meV resolution for losses below 1 eV. We also propose, implement, and test two methods to limit the number of iterations in the algorithm. The first method is based on noise measurement and analysis, while in the second we monitor the change of slope in the deconvolved spectrum.
Multiband rectangular-shaped ring antenna embedded with inverted S- and C-shaped strips for WLAN/WiMAX/UWB applications
Authors: Parkash Davinder , Khanna Rajesh
Published: April 2014

This research work presents a microstrip-fed antenna that is small, low-profile, planar, and suitable for WLAN/WiMAX and partially ultra-wideband (UWB) applications. The radiating element of the proposed antenna consists of rectangular-shaped ring embedded with a three inverted “S”-shaped and inverted “C”-shaped strips. This antenna is capable of generating penta bands having good impedance matching with wideband characteristics. Prototype of the proposed antenna has been designed, simulated, fabricated, and tested. The overall small size of the antenna is 24.75 mm × 27.39 mm × 1.6 mm with volumetric size of 1 cm3. To understand the characteristics of the proposed antenna, the parametric studies are being performed. The return loss of the proposed antenna shows fair agreement with the simulated and measured results.
Screening for Depression and Anxiety Disorders from Pregnancy to Postpartum with the EPDS and STAI
Authors: Tendais Iva , Costa Raquel , Conde Ana , Figueiredo Bárbara
Published: April 2014

The Edinburgh Postnatal Depression Scale (EPDS) and the State Anxiety Inventory (STAI-S) are widely used self-report measures that still need to be further validated for the perinatal period. The aim of this study was to examine the screening performance of the EPDS and the STAI-S in detecting depressive and anxiety disorders at pregnancy and postpartum. Women screening positive on EPDS (EPDS ≥ 9) or STAI-S (STAI-S ≥ 45) during pregnancy (n = 90), as well as matched controls (n = 58) were selected from a larger study. At 3 months postpartum, 99 of these women were reassessed. At a second stage, women were administered a clinical interview to establish a DSM-IV-TR diagnosis. Receiver operator characteristics (ROC) analysis yielded areas under the curve higher than .80 and .70 for EPDS and STAI-S, respectively. EPDS and STAI-S optimal cut-offs were found to be lower at postpartum (EDPS = 7; STAI-S = 34) than during pregnancy (EPDS = 9; STAI-S = 40). EPDS and STAI-S are reasonably valid screening tools during pregnancy and the postpartum.
Faktorenstruktur, psychometrische Eigenschaften und Messinvarianz der deutschsprachigen Version des 60-Item HEXACO Persönlichkeitsinventars
Authors: Moshagen Morten , Hilbig Benjamin E. , Zettler Ingo
Published: April 2014

Im letzten Jahrzehnt wurden in lexikalischen Untersuchungen über diverse Sprachen und Kulturen hinweg sechs grundlegende Persönlichkeitseigenschaften identifiziert, welche im HEXACO-Modell der Persönlichkeit abgebildet werden. Die vorliegende Untersuchung behandelt eine umfangreiche psychometrische Evaluation der deutschen Version des 60-Item HEXACO-Persönlichkeitsinventars. Die sechsfaktorielle Struktur wurde anhand einer großen Stichprobe (N = 3240) bestätigt. Die resultierenden Faktoren verfügten über zufriedenstellende Reliabilitäten und waren praktisch unkorreliert. Überdies konnte Messinvarianz über das Geschlecht belegt werden. Anhand einer weiteren Stichprobe (N = 1012) wurde gezeigt, dass die 60-Item Version zu keinem bedeutsamen Informationsverlust gegenüber der 96-Item Version führt. Die Bestimmung von Korrelationen zu den Big-Five Persönlichkeitsfaktoren mittels einer dritten Stichprobe (N = 235) erbrachte durchweg erwartungskonforme Ergebnisse. Letztlich konnten anhand einer vierten Stichprobe (N = 31) hohe Retest-Reliabilitäten über einen Zeitraum von 7 Monaten belegt werden. Somit eignet sich die deutschsprachige Version des HEXACO-60 Persönlichkeitsinventars zur reliablen, validen und verhältnismäßig ökonomischen Erfassung der sechs Faktoren des HEXACO-Modells der Persönlichkeit.
Plasmonic Excitations of 1D Metal-Dielectric Interfaces in 2D Systems: 1D Surface Plasmon Polaritons
Authors: Mason Daniel R. , Menabde Sergey G. , Yu Sunkyu , Park Namkyoo
Published: April 2014

Surface plasmon-polariton (SPP) excitations of metal-dielectric interfaces are a fundamental light-matter interaction which has attracted interest as a route to spatial confinement of light far beyond that offered by conventional dielectric optical devices. Conventionally, SPPs have been studied in noble-metal structures, where the SPPs are intrinsically bound to a 2D metal-dielectric interface. Meanwhile, recent advances in the growth of hybrid 2D crystals, which comprise laterally connected domains of distinct atomically thin materials, provide the first realistic platform on which a 2D metal-dielectric system with a truly 1D metal-dielectric interface can be achieved. Here we show for the first time that 1D metal-dielectric interfaces support a fundamental 1D plasmonic mode (1DSPP) which exhibits cutoff behavior that provides dramatically improved light confinement in 2D systems. The 1DSPP constitutes a new basic category of plasmon as the missing 1D member of the plasmon family: 3D bulk plasmon, 2DSPP, 1DSPP and 0D localized SP.
Crash and rebound of indigenous populations in lowland South America
Authors: Hamilton Marcus J. , Walker Robert S. , Kesler Dylan C.
Published: April 2014

Lowland South America has long been a battle-ground between European colonization and indigenous survival. Initial waves of European colonization brought disease epidemics, slavery and violence that had catastrophic impacts on indigenous cultures. In this paper we focus on the demography of 238 surviving populations in Brazil. We use longitudinal censuses from all known indigenous Brazilian societies to quantify three demographic metrics: 1) effects of European contact on indigenous populations; 2) empirical estimates of minimum viable population sizes; and 3) estimates of post-contact population growth rates. We use this information to conduct population viability analysis (PVA). Our results show that all surviving populations suffered extensive mortality during and shortly after, contact. However, most surviving populations exhibit positive growth rates within the first decade post-contact. Our findings paint a positive demographic outlook for these indigenous populations, though long-term survival remains subject to powerful externalities, including politics, economics and the pervasive illegal exploitation of indigenous lands.
Xanthine Oxidase Inhibition by Febuxostat Attenuates Experimental Atherosclerosis in Mice
Authors: Nomura Johji , Busso Nathalie , Ives Annette , Matsui Chieko , Tsujimoto Syunsuke , Shirakura Takashi , Tamura Mizuho , Kobayashi Tsunefumi , So Alexander , Yamanaka Yoshihiro
Published: April 2014

Atherosclerosis is a chronic inflammatory disease due to lipid deposition in the arterial wall. Multiple mechanisms participate in the inflammatory process, including oxidative stress. Xanthine oxidase (XO) is a major source of reactive oxygen species (ROS) and has been linked to the pathogenesis of atherosclerosis, but the underlying mechanisms remain unclear. Here, we show enhanced XO expression in macrophages in the atherosclerotic plaque and in aortic endothelial cells in ApoE−/− mice and that febuxostat, a highly potent XO inhibitor, suppressed plaque formation, reduced arterial ROS levels and improved endothelial dysfunction in ApoE−/− mice without affecting plasma cholesterol levels. In vitro, febuxostat inhibited cholesterol crystal-induced ROS formation and inflammatory cytokine release in murine macrophages. These results demonstrate that in the atherosclerotic plaque, XO-mediated ROS formation is pro-inflammatory and XO-inhibition by febuxostat is a potential therapy for atherosclerosis.
Synthesis of NASICON-type structured NaTi2(PO4)3–graphene nanocomposite as an anode for aqueous rechargeable Na-ion batteries
Authors: Pang Gang , Yuan Changzhou , Nie Ping , Ding Bing , Zhu Jiajia , Zhang Xiaogang
Published: April 2014

NASICON-type structured NaTi2(PO4)3 nanoparticles homogeneously anchored on the surface of graphene nanosheets have been synthesized by a solvothermal approach. Due to the unique structures, the electrode exhibits excellent electrochemical performance as a potential anode for Na-ion batteries.
Magnetic field assisted growth of highly dense α-Fe2O3 single crystal nanosheets and their application in water treatment
Authors: Lin Dong , Deng Biwei , Sassman Stephen A. , Hu Yaowu , Suslov Sergey , Cheng Gary J.
Published: April 2014

Highly dense 2D nanostructures are desirable in photocatalysis, water treatment and energy storage, due to their high surface to volume areas.
Microchip electrophoresis with amperometric detection method for profiling cellular nitrosative stress markers
Authors: Gunasekara Dulan B. , Siegel Joseph M. , Caruso Giuseppe , Hulvey Matthew K. , Lunte Susan M.
Published: April 2014

Microchip electrophoresis method for the simultaneous determination of intracellular nitrosative stress markers and endogenous antioxidants in native and stimulated macrophage cells.
Ditopic bis-terdentate cyclometallating ligands and their highly luminescent dinuclear iridium(iii) complexes
Authors: Lanoë Pierre-Henri , Tong Chi Ming , Harrington Ross W. , Probert Michael R. , Clegg William , Williams J. A. Gareth , Kozhevnikov Valery N.
Published: April 2014

Luminescent dinuclear Ir(iii) complexes of a bis-N∧C∧N-coordinating ligand are reported with two metal ions bound to a central pyrimidine. A pair of enantiomers and a meso form have been structurally characterised.
In situ fabrication of Cu2ZnSnS4 nanoflake thin films on both rigid and flexible substrates
Authors: Zhai Xuezhen , Jia Huimin , Zhang Yange , Lei Yan , Wei Jie , Gao Yuanhao , Chu Junhao , He Weiwei , Yin Jun-Jie , Zheng Zhi
Published: April 2014

Pure CZTS thin film is formed directly at a temperature of 250 °C, the lowest temperature of any current fabrication system, on both flexible stainless steel and rigid FTO substrates.
Five Cd(ii) coordination polymers based on 2,3′,5,5′-biphenyltetracarboxylic acid and N-donor coligands: syntheses, structures and fluorescent properties
Authors: Chang Xin-Hong , Zhao Ying , Han Min-Le , Ma Lu-Fang , Wang Li-Ya
Published: April 2014

Five Cd(ii) coordination polymers based on 2,3′,5,5′-biphenyltetracarboxylic acid and different bis(imidazole) ligands have been synthesized.
Mechanisms of enhanced sulfur tolerance on samarium (Sm)-doped cerium oxide (CeO2) from first principles
Authors: Lim Dong-Hee , Kim Hee Su , Yoon Sung Pil , Han Jonghee , Yoon Chang Won , Choi Sun Hee , Nam Suk Woo , Ham Hyung Chul
Published: April 2014

The role of samarium (Sm) 4f states and Sm-perturbed O 2p states in determining the sulfur tolerance of Sm-doped CeO2 was elucidated by using the density functional theory (DFT) + U calculation.
Defining chemical expansion: the choice of units for the stoichiometric expansion coefficient
Authors: Marrocchelli Dario , Chatzichristodoulou Christodoulos , Bishop Sean R.
Published: April 2014

Guidelines for presenting the stoichiometric expansion coefficient (αS), relating strain to iso-structural changes in composition, are discussed.
Crystal chemistry and luminescence properties of red-emitting CsGd1−xEux(MoO4)2 solid-solution phosphors
Authors: Shi Pinglu , Xia Zhiguo , Molokeev Maxim S. , Atuchin Victor V.
Published: April 2014

The crystal structure and red-emitting luminescence properties of scheelite related CsGd1−xEux(MoO4)2 solid-solution phosphors have been investigated.
Theoretical investigation of the charge-transfer properties in different meso-linked zinc porphyrins for highly efficient dye-sensitized solar cells
Authors: Namuangruk Supawadee , Sirithip Kanokkorn , Rattanatwan Rattanawelee , Keawin Tinnagon , Kungwan Nawee , Sudyodsuk Taweesak , Promarak Vinich , Surakhot Yaowarat , Jungsuttiwong Siriporn
Published: April 2014

In an attempt to improve the photoinduced intramolecular-charge transfer ability of a meso-linked zinc porphyrin by introducing CN to the anchoring group.
Perspective: what is known, and not known, about the connections between alkane oxidation and metal uptake in alkanotrophs in the marine environment
Authors: Austin Rachel Narehood , Kenney Grace E. , Rosenzweig Amy C.
Published: April 2014

Highlighting what is known and not known about the co-regulation of metal acquisition and alkane oxidation in the marine environment.
Self-assembly of novel benzimidazole N-glycosylamines into nanofibers and nanospheres
Authors: Dhinakaran Manivannan Kalavathi , Soundarajan Kamalakannan , Mohan Das Thangamuthu
Published: April 2014

Cu2+ ions induce the change in the morphology of self-assembled benzimidazole N-glycosylamines from nano-fibers to nano-spheres.
A ratiometric fluorescent hydrogel sensor for zinc(ii) based on a two fluorophore approach
Authors: Hamilton Graham R. C. , Fullerton Lewis , McCaughan Bridgeen , Donnelly Ryan F. , Callan John F.
Published: April 2014

A hydrogel sensor has been developed to measure the concentration of Zn(ii) upon swelling in aqueous buffer.
Uniform Ni/SiO2@Au magnetic hollow microspheres: rational design and excellent catalytic performance in 4-nitrophenol reduction
Authors: Zhang Shenghuan , Gai Shili , He Fei , Dai Yunlu , Gao Peng , Li Lei , Chen Yujin , Yang Piaoping
Published: April 2014

Uniform Ni/SiO2 magnetic hollow microspheres were prepared by an in situ thermal decomposition and reduction route. Tiny Au nanoparticles (5 nm) were linked to Ni/SiO2 microspheres. The as-prepared Ni/SiO2@Au catalysts exhibited excellent catalytic activity for 4-nitrophenol reduction.
On the roles of graphene oxide doping for enhanced supercurrent in MgB2 based superconductors
Authors: Yeoh W. K. , Cui X. Y. , Gault B. , De Silva K. S. B. , Xu X. , Liu H. W. , Yen H.–W. , Wong D. , Bao P. , Larson D. J. , Martin I. , Li W. X. , Zheng R. K. , Wang X. L. , Dou S. X. , Ringer S. P.
Published: April 2014

Advanced microscopy techniques and computational simulation to reveal the atomic-scale mechanisms for the highest ever recorded enhancement of supercurrent in MgB2-based superconductors.
Reducing ZnO nanoparticle cytotoxicity by surface modification
Authors: Luo Mingdeng , Shen Cenchao , Feltis Bryce N. , Martin Lisandra L. , Hughes Anthony E. , Wright Paul F. A. , Turney Terence W.
Published: April 2014

ZnO surface properties control cytotoxicity by regulating nanoparticle uptake rather than by altering either intracellular or extracellular Zn dissolution rates.
Enhanced photoelectrochemical water splitting performance of TiO2nanotube arrays coated with an ultrathin nitrogen-doped carbon film by molecular layer deposition
Authors: Tong Xili , Yang Peng , Wang Yunwei , Qin Yong , Guo Xiangyun
Published: April 2014

TiO2nanotube arrays coated with a carbon film by MLD exhibit excellent capability for PEC water splitting with an optimized carbon-film thickness.
Hollow manganese phosphonate microspheres with hierarchical porosity for efficient adsorption and separation
Authors: Zhu Yun-Pei , Liu Ya-Lu , Ren Tie-Zhen , Yuan Zhong-Yong
Published: April 2014

Hollow microspheres of hierarchical porous manganese phosphonate were prepared template-free, exhibiting high efficiency for metal ion adsorption and protein separation.
Full pH-range responsive hyperbranched polyethers: synthesis and responsiveness
Authors: Xia Yumin , Wang Xinhang , Wang Yanping , Wang Yimin
Published: April 2014

In order to impart full pH-range responsiveness within biocompatible hyperbranched polyethers, new amphiphilic polyethers, i.e. HPMHO–Amines and HPMHO–Carboxys, which have a molecular structure similar to hyperbranched PEG, were prepared through ring-opening polymerization and modified by amination or carboxylation.
An expedient route to heterocycles through α-arylation of ketones and arylamides by microwave induced thermal SRN1 reactions
Authors: Soria-Castro Silvia M. , Caminos Daniel A. , Peñéñory Alicia B.
Published: April 2014

Quick reaction by microwave irradiation promotes nucleophilic substitution by thermally induced electron transfer mechanism and allows to synthesize deoxibenzoin and indol heterocycles derivates by inter or intramolecular ring closure.
A highly efficient iron doped BaTiO3nanocatalyst for the catalytic reduction of nitrobenzene to azoxybenzene
Authors: Srilakshmi Ch. , Vijay Kumar H. , Praveena K. , Shivakumara C. , Muralidhar Nayak M.
Published: April 2014

A heterogeneous Fe doped BaTiO3efficient nanocatalyst for the catalytic reduction of nitrobenzene (NB) to synthesize azoxybenzene (AOB) in the presence of 2-propanol and molecular H2has been investigated. This method offers 100% NB conversion with 93–95% AOB yield.
Synthesis of 6-aminophenanthridines via palladium-catalyzed insertion of isocyanides into N-sulfonyl-2-aminobiaryls
Authors: Jiang Huanfeng , Gao Hanling , Liu Bifu , Wu Wanqing
Published: April 2014

A robust route to a diverse set of 6-aminophenanthridines via palladium-catalyzed C–H activation of N-sulfonyl-2-aminobiaryl and isocyanide insertion is reported.
Sequence-responsive unzipping DNA cubes with tunable cellular uptake profiles
Authors: Bujold Katherine E. , Fakhoury Johans , Edwardson Thomas G. W. , Carneiro Karina M. M. , Briard Joel Neves , Godin Antoine G. , Amrein Lilian , Hamblin Graham D. , Panasci Lawrence C. , Wiseman Paul W. , Sleiman Hanadi F.
Published: April 2014

Here, we demonstrate a new approach for the design and assembly of a dynamic DNA cube with an addressable cellular uptake profile.
Jahn–Teller orbital glass state in the expanded fcc Cs3C60 fulleride
Authors: Potočnik A. , Ganin A. Y. , Takabayashi Y. , McDonald M. T. , Heinmaa I. , Jeglič P. , Stern R. , Rosseinsky M. J. , Prassides K. , Arčon D.
Published: April 2014

Magic-angle-spinning NMR measurements on fcc Cs3C60 to cryogenic temperatures reveal freezing-out of the C603¬ Jahn–Teller dynamics and emergence of an electronic orbital glass state guided by the C603¬ merohedral disorder.
Structural evolution of high energy density V3+/V4+ mixed valent Na3V2O2x(PO4)2F3−2x (x = 0.8) sodium vanadium fluorophosphate using in situ synchrotron X-ray powder diffraction
Authors: Serras Paula , Palomares Verónica , Rojo Teófilo , Brand Helen E. A. , Sharma Neeraj
Published: April 2014

The first time-resolved in situ synchrotron XRD study of a cathode in a functioning sodium-ion battery. We determine the reaction mechanism, lattice parameters, sodium evolution, and the maximum sodium extraction for the fresh and precycled cell.
Chemical patterning on preformed porous silicon photonic crystals: towards multiplex detection of protease activity at precise positions
Authors: Zhu Ying , Soeriyadi Alexander H. , Parker Stephen G. , Reece Peter J. , Gooding J. Justin
Published: April 2014

Porous silicon rugate filters were chemically patterned with biomolecules and used for multiplex detection of protease activity at precise positions.
Structure and photoluminescence properties of novel Ca2NaSiO4F:Re (Re = Eu2+, Ce3+, Tb3+) phosphors with energy transfer for white emitting LEDs
Authors: Jiao Mengmeng , Jia Yongchao , Lü Wei , Lv Wenzhen , Zhao Qi , Shao Baiqi , You Hongpeng
Published: April 2014

The Eu2+, Ce3+ and Tb3+ doped Ca2NaSiO4F phosphors were prepared, and their luminescence properties have been investigated systematically.
Interference masking for secure wireless broadcast communications
Authors: Ding Zhiguo , Leung Kin K. , Poor H. Vincent
Published: April 2014

Physical layer security has been recognised as a promising technique to realise secure wireless communications. A novel interference masking approach is proposed for secure broadcast scenarios. Specifically, when there is an external jamming node, precoding matrices at the source and jammer are carefully designed to ensure that each destination can detect only its own message, and not the information intended for other destinations which is masked with artificial noise. When there is no external jamming node, interference masking is implemented through user cooperation, in which destinations switch roles from jammer to relay nodes during different time slots. Both analytical and numerical results are provided to demonstrate the performance of the proposed approaches.
Physical layer security in power line communication networks: an emerging scenario, other than wireless
Authors: Pittolo Alberto , Tonello Andrea M.
Published: April 2014

The authors consider the secure transmission of information over power line communication (PLC) networks. The focus is on the secrecy guaranteed at the physical layer, named physical layer security (PLS). Although PLS has been deeply investigated for the wireless case, it is not the same for the PLC environment. Thus, starting from the knowledge in the wireless context, the authors extend the results to typical PLC scenarios. In particular, the PLC channel statistics is evaluated and a performance comparison among PLC and wireless channels is performed, in terms of secrecy rate distribution. For the PLC case, the secrecy rate distribution, under a total power constraint, is evaluated for both optimal and uniform power distributions in broadband channels. To provide experimental evidence, the authors consider channel measures obtained in an in‐home measurement campaign. The underlying network presents a tree topology, which introduces frequency and spatial correlation among channels, and suffers from the keyhole effect, generated by branches that depart from the same node. As shown by the numerical results, these effects can reduce the secrecy rate. Finally, the authors evaluate the secrecy rate region for the multi‐user broadcast channel considering both simulated channel realisations and experimental channel measures.
Set partitioning of Gaussian integer constellations and its application to two‐dimensional interleaving
Authors: Freudenberger Jürgen , Spinner Jens , Shavgulidze Sergo
Published: April 2014

Codes over Gaussian integers have been proposed for coding over two‐dimensional (2D) signal spaces, for example, using quadrature amplitude modulation. Here, it is demonstrated that the concept of set partitioning can be applied to Gaussian integer constellations that are isomorphic to 2D modules over rings of integers modulo p. This enables multilevel code constructions over Gaussian integers. The authors derive upper bounds on the achievable minimum distance in the subsets and present a construction for the set partitioning. This construction achieves optimal or close to optimal minimum distances. Furthermore, it is demonstrated that this set partitioning can be applied to an interleaving technique for correcting 2D cyclic clusters of errors. The authors propose a novel combination of generalised concatenated codes with 2D interleaving to correct 2D error clusters and independent errors.
Adaptive modulation and coding for two‐way relaying with amplify‐and‐forward protocols
Authors: Sun Shaohui , Yang Kun , Wu Jianjun , Zhu Dalin , Lei Ming
Published: April 2014

In this study, the authors introduce adaptive modulation and coding in a two‐way amplify‐and‐forward (AF) relay network to improve the system performance. They consider a cooperative system where two user nodes exchange information with the assistance of multiple two‐way AF relays. In the proposed scheme, the user nodes adaptively choose the appropriate modulation and coding scheme to ensure that the frame error rate (FER) satisfies the system requirement; all relays are utilised to forward the received signals to the user terminals. Furthermore, they provide a better approximation of the cumulative distribution function of the destination signal‐to‐noise ratio; and thus, derive more accurate expressions including average spectral efficiency and average FER in closed‐form, over Rayleigh fading channels. The theoretical analysis is verified by numerical results.
Combination synchronisation of different kinds of spatiotemporal coupled systems with unknown parameters
Authors: Hao Zhang , Xing‐yuan Wang , Xiao‐hui Lin
Published: April 2014

In this study, spatiotemporal coupled systems with different kinds of local dynamic behaviours are introduced and combination synchronisation in such systems is studied. Especially, complex spatiotemporal coupled system consists of real number part and imaginary number part, so it can be synchronised with two real number systems at the same time and synchronisation is asymmetrical. Based on the backstepping method, the authors design controllers (fewer than the number of variables) with parameters identification. Sliding mode controllers are designed according to the Lyapunov stability theory and the fractional stability theory. Simulation results show the robustness and effectiveness of the authors methods.
Background segmentation of dynamic scenes based on dual model
Authors: Yin Baocai , Zhang Jing , Wang Zengfu
Published: April 2014

Detecting moving objects from background in video sequences is the first step of many image applications. The background can be divided into two types according to whether the pixel values of it are variable or not: static one and dynamic one. How to correctly detect moving foreground objects from dynamic scenes is a difficult problem because of the similarity between the moving foreground and the variable background. In this study, a new method for non‐parametric background segmentation of dynamic scenes is proposed. Here the background is described by two interrelated models. One of them is called the self‐model, which concerns with the recently observed pixel values at the same position, and the other one is called the neighbourhood‐model, which is described by the pixel values of the neighbourhood. The author's method can accurately detect the dynamic background. To correctly detect pixels in the foreground as much as possible, the authors also propose an adaptive threshold for foreground decision based on the background characteristics. All of the above detection processes can be done in real time. Experimental results on public dataset demonstrate that the proposed method outperforms the state‐of‐the‐art for background segmentation in dynamic scenes.
Induced pole rotor structure for line start permanent magnet synchronous motors
Authors: Ugale Rajaram Tukaram , Chaudhari Bhalchandra Nemichand , Baka Srinivas , Dambhare Sanjay Shamrao , Pramanik Ashutosh
Published: April 2014

This study presents a rotor structure, for a line start permanent magnet synchronous motors (LSPMSMs), which can be applied to other types of inverter driven motors, such as brushless dc and permanent magnet synchronous motors. In this development, the magnet configuration is a combination of both circumferentially (spoke) as well as radially magnetised (embedded) magnets which are so arranged that induced poles are generated in alternate positions in the heteropolar structure, thereby reducing the quantity of permanent magnets in the rotor. Both the transient as well as steady‐state performances of the machine have been analysed by using time‐stepping finite element method. For experimental demonstration a prototype which uses spoke magnets (P1), plus two prototypes (P2 and P3) of the proposed magnet arrangement have been built. The former (P1) is used for benchmarking the performance of the proposed configuration. Results have indicated that the rotor configuration reported here (P2) with reduced magnet volume gives better performance than the spoke magnet rotor LSPMSM. Also, the performances of prototype LSPMSMs are compared with that of the standard induction motor of the same frame size and physical dimensions.
Magnet asymmetry in reduction of cogging torque for integer slot axial flux permanent magnet motors
Authors: Gulec Mehmet , Aydin Metin
Published: April 2014

Cogging torque component is one of the key issues in the design of radial and axial gap permanent magnet motors and the geometry and the position of the magnets plays a critical role in this process. This study presents the influence of magnet asymmetry in minimisation of the cogging torque for axial flux permanent magnet (AFPM) disc motors. Cogging torque minimisation techniques, such as magnet skewing and magnet shifting or groping are examined in detail by using three‐dimensional finite element analysis with various types of magnet skewing alternatives since the shaping and the positioning magnets are low cost approaches to minimise or eliminate the cogging component. A prototype AFPM disc motor is built with shifted magnets based on the models which are the results validated with the experimental results for the minimum cogging component and the sinusoidal back‐EMF waveform. It is shown in this study that the cogging component in AFPM motors can be practically eliminated by using magnet asymmetry and perfectly sinusoidal back‐EMF can also be obtained even for integer slot/pole/phase motors.
Voltage balancing in low‐voltage radial feeders using Scott transformers
Authors: Li Yun , Crossley Peter A
Published: April 2014

Increasing use of heat pumps, micro‐generation, electric vehicles and energy‐saving technologies is expected to cause severe voltage imbalance on low‐voltage (LV) radial feeders and deteriorate the power quality seen by single‐phase (1Φ) and three‐phase (3Φ) LV connected consumers. To solve this problem, a Scott transformer‐based balancing technique is used to convert an unbalanced 3Φ supply into a balanced 3Φ supply at either one point on an LV radial feeder or a 3Φ load supply point. Moreover, by replacing the traditional methods of increasing LV cable cross‐sections to solve voltage imbalance; or future solutions such as automatic network reconfiguration, the economic cost of operating and upgrading a ‘stressed’ LV feeder can be minimised. A computer simulation study, in which the proposed method is used to balance a typical UK LV network, with varying levels of imbalance, was carried out. Furthermore, a ‘small‐scale’ physical voltage balancing system based on the proposed method was constructed and tested in the laboratory. The results obtained from various simulation and experimental scenarios demonstrated that the proposed method can continuously maintain a balanced 3Φ supply by compensating for phase‐related voltage dips and surges resulting from variations in 1Φ connected loads.
Classification and regression tree‐based adaptive damping control of inter‐area oscillations using wide‐area signals
Authors: Wang Tong , Wang Zengping , Liu Jizhen , Thorp James S. , Yang Yuan
Published: April 2014

An adaptive damping control scheme based on classification and regression tree (CART) using wide‐area signals is proposed in this study. A family of robust controllers is designed off‐line and are used in real‐time after the corresponding operating point is retrieved from phasor measurement unit (PMU) data with CART interpolation. When the power system is operating precisely at a pre‐selected operating point, only the corresponding controller is active. When the power system is not exactly at the operating point, a combined controller is formed for damping. A 68‐bus, 16‐generator system is used as a test system. A thyristor‐controlled series capacitor, a static var compensator and an energy storage device are used as actuators, and remote PMUs frequencies as added inputs are employed as the example control. The simulation results demonstrate the effectiveness and robustness against the wider range of operating changes even without knowing precisely the model of disturbances that occurred in the dynamic system.
Medical image denoising by generalised Gaussian mixture modelling with edge information
Authors: Cong‐Hua Xie , Jin‐Yi Chang , Wen‐Bin Xu
Published: April 2014

Denoising is a classical challenging problem in medical image processing and understanding. In this study, the authors propose a novel generalised Gaussian mixture model (GGMM) with edge information to denoise medical images. In the first stage, they extend Gaussian mixture model to the GGMM for modelling the noisy medical images and use minimum‐mean‐square error under the Bayesian framework to derive a non‐linear mapping function for processing the noisy images. In the second stage, they refine the results by the kernel density function of the edge information. Experimental results on the Simulated Brain Database and real computed tomography abdomen images demonstrate that GGMM‐Edge Information achieves very competitive denoising performance, especially the image grey, visual quality and edge preservation in detail, compared with several state‐of‐the‐art denoising algorithms.
Autonomous collision avoidance system based on accurate knowledge of the vehicle surroundings
Authors: Jiménez Felipe , Naranjo José Eugenio , Gómez Óscar
Published: April 2014

In this study, a collision avoidance system is presented, based on the information provided by a laser‐scanner sensor, in which two actions could be taken in case of danger. Firstly, the system tries to stop the vehicle in order to avoid the accident. If a reduction in speed is not sufficiently effective, the control system takes control of the steering and deviates the vehicle's trajectory in order to escape from the hazardous situation. The control system evaluates the situation and decides the most appropriate action in each case considering free areas on the surroundings using the information of a detailed digital map. This system has been implemented in a vehicle and has been tested with pedestrians and vehicles circulating along the private test track with satisfactory results.
On creating vision‐based advanced driver assistance systems
Authors: Nieto Marcos , Otaegui Oihana , Vélez Gorka , Ortega Juan Diego , Cortés Andoni
Published: April 2014

In this study, the authors analyse the exponential growth of advanced driver assistance systems based on video processing in the past decade. Specifically, they focus on how research and innovative ideas can finally reach the market as cost‐effective solutions. They explore well‐known computer vision methods for services like lane departure warning systems, collision avoidance systems and point out potential future trends according to a review of the state‐of‐the‐art. Along this study, the authors’ own contributions are described as examples of such systems from the perspective of real‐time by design, pursuing a trade‐off between the accuracy and reliability of the designed algorithms and the restrictive computational, economical and design requisites of embedded platforms.
Cost effective railway signalling by wireless communication among onboard controllers and switch controllers
Authors: Katsuta Keiichi
Published: April 2014

The signalling system is one of the most costly systems in the railway infrastructure. The cost of the trackside controllers is particularly high because high‐performance failsafe hardware and software are needed to supervise and control the many pieces of the field equipment. A signalling system is described that has a lower projected cost because of the application of the traditional token block mechanism to the virtual blocks dividing each controlled section. Its basic mechanism is the sharing by the wireless communication of the information about the exclusive rights with the virtual blocks, the status of the switches and the instructions for controlling the switches in the controlled section among the onboard controllers and the switch controllers, respectively. A telegram for each controlled section is circulated in turn among these controllers for the sharing. This mechanism provides an automatic train protection and an interlocking function without using the trackside controllers. Its application to a very high‐density line might reduce the train operation density because of the telegram circulation time, but the reduction would be no greater than 20% on the highest density line if the current radio technology was used. A cost evaluation based on a 20‐km double‐track line showed that this system is about three times more cost effective than the communication‐based train control system.
Performance approximations and bounds for non‐real‐time traffic in an integrated service system
Authors: Huang Yue‐Cai , Ko King‐Tim , Zukerman Moshe
Published: April 2014

The authors consider an integrated service system, where real‐time (RT) calls of multiple rate requirements and non‐real‐time (NRT) calls share the total system capacity. Typically, RT calls are given strict priority over NRT calls; therefore NRT performance is dependent on the RT process. When RT call arrivals do not follow a Poisson process, the effect of the RT traffic burstiness on the NRT performance has not been investigated. In this study, the authors investigate this effect and provide computationally efficient approximations and bounds for the NRT performance evaluation in the integrated service system with multi‐rate non‐Poisson RT traffic. With known first and second moments of the RT call arrival processes, the authors propose to consider the multi‐rate non‐Poisson RT traffic streams as an equivalent single‐rate Poisson traffic stream. Then, the authors evaluate the NRT performance by converting the original system to a system offered with the equivalent RT traffic and the NRT traffic. The authors’ approximations and bounds are validated by extensive numerical examples.
Internet traffic modelling: from superposition to scaling
Authors: Arfeen Muhammad Asad , Pawlikowski Krzysztof , Willig Andreas , McNickle Don
Published: April 2014

Internet traffic at various tiers of service providers is essentially a superposition or active mixture of traffic from various sources. Statistical properties of this superposition and a resulting phenomenon of scaling are important for network performance (queuing), traffic engineering (routing) and network dimensioning (bandwidth provisioning). In this article, the authors study the process of superposition and scaling jointly in a non‐asymptotic framework so as to better understand the point process nature of cumulative input traffic process arriving at telecommunication devices (e.g., switches, routers). The authors further assess the scaling dynamics of the structural components (packets, flows and sessions) of the cumulative input process and their relation with superposition of point processes. Classical and new results are discussed with their applicability in access and core networks. The authors propose that renewal theory‐based approximate point process models, that is, Pareto renewal process superposition and Weibull renewal process superposition can model the similar second‐order scaling, as observed in traffic data of access and backbone core networks, respectively.
Simulated dynamics of optically pumped dilute nitride 1300 nm spin vertical‐cavity surface‐emitting lasers
Authors: Alharthi Sami S. , Al Seyab Rihab K. , Henning Ian D. , Adams Michael J.
Published: April 2014

The authors report a theoretical analysis of optically pumped 1300 nm dilute nitride spin‐polarised vertical‐cavity surface‐emitting lasers (VCSELs) using the spin‐flip model to determine the regions of stability and instability. The dependence of the output polarisation ellipticity on that of the pump is investigated, and the results are presented in two‐dimensional contour maps of the pump polarisation against the magnitude of the optical pump. Rich dynamics and various forms of oscillatory behaviour causing self‐sustained oscillations in the polarisation of the spin‐VCSEL subject to continuous‐wave pumping have been found because of the competition of the spin‐flip processes and birefringence. The authors also reveal the importance of considering both the birefringence rate and the linewidth enhancement factor when engineering a device for high‐frequency applications. A very good agreement is found with the experimental results reported by the authors’ group.
Low‐strain, quantum‐cascade‐laser active regions grown on metamorphic buffer layers for emission in the 3.0–4.0 μm wavelength region
Authors: Mawst Luke J. , Kirch Jeremy D. , Kim TaeWan , Garrod Toby , Boyle Colin , Botez Dan , Zutter Brian , Schulte Kevin , Kuech Thomas F. , Bouzi Pierre M. , Gmachl Claire F. , Earles Thomas
Published: April 2014

We have investigated metamorphic buffer layers (MBLs), as so‐called virtual substrates, for accessing a compositional range of Inx Ga1−x As/Aly In1−y As superlattice (SL) materials which would otherwise be prohibited due to excessive strain when grown on conventional substrates. Such materials have application in the realisation of high‐performance Quantum Cascade Lasers (QCLs) of short emission wavelengths (i.e., ≤4.0 μm). Simulation studies suggest that significant enhancement of performance in terms of reduced device temperature sensitivity and reduced thermal resistance is possible over conventional InP‐substrate devices by employing MBL‐based QCL designs on a GaAs substrate. Furthermore, such devices would exhibit significantly lower strain compared to conventional QCLs on InP emitting within the 3.0–4.0 μm wavelength region. To improve the planarity of MBL top surfaces, we employ chemical mechanical polishing (CMP) prior to the growth of the QCL SL structures. 20‐period Inx Ga1− x As (wells)/Aly In1− y As (barriers) SLs are grown by metalorganic vapour phase epitaxy (MOVPE) on an InGaAs step‐graded, hydride vapour phase epitaxy (HVPE)‐grown MBL. Employing CMP on the top of the MBL, prior to the SL growth, results in significantly improved X‐ray‐diffraction SL fringes. Electroluminescent devices, incorporating a single stage of QCL‐SL active‐region material grown on an MBL subjected to CMP, demonstrate intersubband emission near 3.6 μm.
Cost‐based droop scheme with lower generation costs for microgrids
Authors: Nutkani Inam Ullah , Chiang Loh Poh , Blaabjerg Frede
Published: April 2014

In an autonomous microgrid where centralised management and communication links are not viable, droop control has been the preferred scheme for distributed generators (DGs). At present, although many droop variations have surfaced, they mainly focus on achieving proportional power sharing based on the DG kilovolts ampere (kVA) ratings. Other factors like generation costs, efficiencies and emission penalties at different load demands have not been considered. This omission might not be appropriate if different types of DGs are present in the microgrids. As an alternative, this study proposes a cost‐based droop scheme, whose objective is to reduce a generation cost function realised with various DG operating characteristics taken into consideration. Where desired, proportional power sharing based on the DG kVA ratings can also be included, whose disadvantage is a slightly higher generation cost, which is still lower than that produced by the traditional droop schemes. The proposed droop scheme therefore retains all advantages of the traditional droop schemes, whereas at the same time, keeps its generation cost low. These findings have been validated in experiments.
Simulation of three‐level 24‐pulse voltage source converters‐based static synchronous compensator for reactive power control
Authors: Singh Bhim , Kadagala Venkata Srinivas
Published: April 2014

The proposed STATCOM (static synchronous compensator) consists of two sets of three‐level 24‐pulse VSC (voltage source converter) gated at the fundamental frequency. The dc‐link voltage of VSC is maintained at a constant value unlike the common operation of the STATCOM with a variable dc‐link voltage. The phase angle between the ac voltages produced by two sets of three‐level 24‐pulse VSCs is varied for controlling the magnitude of the converter ac voltage which in turn controls the reactive power of the STATCOM. The proposed STATCOM has the advantage of maximum utilisation of the converter as it is operated at a constant dc‐link voltage. The dynamic and steady‐state performances of STATCOM are evaluated by varying the reference reactive power, the reference terminal voltage and switching on inductive and capacitive loads.
Reference‐change response assignment for pulse‐width‐modulated dc–dc converters
Authors: Behjati Hamid , Davoudi Ali
Published: April 2014

A simple yet powerful control method, which allows direct reference‐change response assignment, is employed for pulse‐width‐modulated dc–dc converters. The proposed control method is an extension of the recently‐introduced proportional‐weighted‐integral control. In many applications, such as programmable dc power supplies, the output voltage is expected to demonstrate an almost ideal response upon receiving the reference‐change command. Conventional control methods can only ‘tune’ this response by adjusting different control parameters. The presented method enables direct ‘assignment’ of such response as an arbitrary function of time. Comparing to the existing complex control algorithms, the presented control method is computationally similar to PID controllers and, thus, requires very modest computational resources. Numerical simulations and hardware measurements verify the performance of the presented control method and demonstrate its ability for reference‐change response assignment.
Compensation of three‐phase diode rectifier with capacitive filter working under unbalanced supply conditions using series hybrid active power filter
Authors: Mulla Mahmadasraf Abdulhamid , Rajagopalan Chudamani , Chowdhury Anandita
Published: April 2014

The currents drawn by three‐phase diode rectifiers with capacitive filters under unbalanced supply conditions are highly non‐linear and unbalanced. This configuration draws significantly unbalanced currents even with smaller percentage of unbalance in supply voltages and more unbalance in supply voltages leads to an extreme unbalanced situation like single phasing. This study highlights the unbalance line current problem observed in three‐phase diode rectifier and proposes its compensation using series hybrid active power filter (SHAPF) working with appropriate control strategy. Four distinct modes of operation under unbalanced supply are identified. A new control algorithm which simultaneously compensates for supply voltage unbalance and source current harmonics is applied to compensate the configuration. An experimental model of three‐phase diode rectifier with capacitive filter working under different supply situation is developed to establish identified modes of operation. This configuration is compensated with SHAPF, manufactured using ARM Cortex M4‐based microcontroller and the results of compensation are described in this study.