bluuebunny/crossref_metadata_2025 huggingface dataset:
The AGN content of deep radio surveys and radio emission in radio-quiet AGN. Why every astronomer should care about deep radio fields
Authors: Padovani P. , Bonzini M. , Miller N. , Kellermann K. I. , Mainieri V. , Rosati P. , Tozzi P. , Vattakunnel S.
Published: July 2014

We present our very recent results on the sub-mJy radio source populations at 1.4 GHz based on the Extended Chandra Deep Field South VLA survey, which reaches ~ 30 μJy, with details on their number counts, evolution, and luminosity functions. The sub-mJy radio sky turns out to be a complex mix of star-forming galaxies and radio-quiet AGN evolving at a similar, strong rate and declining radio-loud AGN. While the well-known flattening of the radio number counts below 1 mJy is mostly due to star-forming galaxies, these sources and AGN make up an approximately equal fraction of the sub-mJy sky. Our results shed also light on a fifty-year-old issue, namely radio emission from radio-quiet AGN, and suggest that it is closely related to star formation, at least at z ~ 1.5 − 2. The implications of our findings for future, deeper radio surveys, including those with the Square Kilometre Array, are also discussed. One of the main messages, especially to non-radio astronomers, is that radio surveys are reaching such faint limits that, while previously they were mainly useful for radio quasars and radio galaxies, they are now detecting mostly star-forming galaxies and radio-quiet AGN, i.e., the bulk of the extragalactic sources studied in the infrared, optical, and X-ray bands.
Obscured quasars at redshift z ~ 2
Authors: Del Moro Agnese , Alexander D. , Bauer F. , Daddi E. , Pannella M. , Harrison F. , Mullaney J. , Pope A. , Dickinson M. , Elbaz D.
Published: July 2014

Completing the census of AGN in the Universe is the key to understanding the cosmic evolution of supermassive black holes (SMBH) and galaxies, and to resolving the spectrum of the X-ray background (XRB). However, a large population of AGN, especially the heavily obscured, Compton-thick AGN, are still missing from even the deepest X-ray surveys. The infrared spectra energy distribution (SED) of distant star-forming galaxies can reveal the presence of bright AGN activity. Using some of the deepest infrared, X-ray and radio data available in the GOODS fields, we identify a population of infrared bright quasars at redshift z ~ 2, which are often missed in the X-ray band. Amongst these sources the number of obscured and heavily-obscured quasars is much higher than those previously found in several X-ray and optical selected samples. A unique view on these heavily-obscured quasars is now given at high energies by NuSTAR. I will present the first NuSTAR detection of a heavily obscured quasar at z 2. This source is a potential archetype of the heavily-obscured high-z AGN in which most of the black hole growth is happening, that can explain the mysterious missing fraction of the XRB.
Optical polarization of gamma-ray bright blazars
Authors: Blinov Dmitry , Angelakis E. , Balokovic M. , Fuhrmann L. , Hovatta T. , Katarzyski K. , Khodade P. , King O. , Kus A. , Kylafis N. , Myserlis I. , Panopoulou G. , Papadakis I. , Papamastorakis I. , Pavlidou V. , Pazderska B. , Pazderski E. , Pearson T. , Rajarshi C. , Ramaprakash A. , Readhead A. , Reig P. , Rouneq R. , Tassis K. , Zensus A.
Published: July 2014

We report about first results of the RoboPol project. RoboPol is a large-sample, high-cadence, polarimetric monitoring program of blazars in optical wavelengths, using a camera specifically constructed for this project, mounted at the University of Crete's Skinakas Observatory 1.3 m telescope. The analysis of RoboPol data is conducted in conjunction with Fermi LAT gamma-ray data, and multifrequency radio data from the OVRO (Caltech), F-GAMMA (MPIfR), and Torun (NCU) monitoring programs. Using carefully selected samples of gamma-ray bright and weak blazars we investigate a connection between their optical polarization behaviour and variability properties in gamma. We examine a relationship of gamma flares with polarization angle rotations relying on robust statistical criteria. We analyse also the optical polarization variability itself in order to establish some restrictions on physical models of blazars jets.
Halo Occupation Distribution of AGNs throught Numerical Simulations
Authors: Altamirano-Dévora Liliana , Miyaji Takamitsu , Aceves Héctor
Published: July 2014

Using a set of simulations in the ΛCDM cosmology, and the mass of intermediate X-Ray Active Galactic Nuclei (AGN) dark matter halos (DMH), we study the Halo Occupation Distribution (HOD) of their host DMH and compare with recent observations. We assume that intermediate X-Ray AGNs have been triggered by a major merger of sub-halos inside larger host halos. We find that the binary major merger HOD slope (α ≈ 0.8) do not seem to reproduce the observed HOD slope (α < 0.6) for these type of AGNs. Other mechanisms may be igniting these AGNs.
Hardening of the X-ray spectrum and signature of Fe abundance in Mrk 501 based on the filamentary jet model
Authors: Honda Yasuko S. , Honda Mitsuru
Published: July 2014

We evaluate the synchrotron spectrum of Mrk 501 based on our filamentary jet model. Integrating the contribution from the magnetic fields induced by numerous current filaments with various transverse sizes, we reproduce the observed hardening of the spectrum around X-rays. It is found that the spectral change during 1997-1998 can be explained by the evolution of turbulence. We also propose that the observed dip around 80 keV is attributed to bound-free absorption by Fe atoms, which implies the abundance of heavy nuclei at the tip of the jet.
Coasean method: lessons from the farm
Authors: ALLEN DOUGLAS W.
Published: July 2014

Ronald Coase detested ‘blackboard economics’ and as a result was often criticized for being ‘against theory’. Coase has also been criticized for being overly descriptive in his institutional analysis. Here, I claim that Coase was both theoretical and interested in hypothesis testing. In order to do Coasean analysis, however, it is necessary to analyse a subject matter at the deep transaction level, given the definition of transaction costs. The rich level of detail required may give the impression of an absence of theory or testing. Here, I provide a number of real farm examples and contrast them with blackboard farm economics to make this point.
The Subjective Bases of Abortion Attitudes: A Cross National Comparison of Religious Traditions
Authors: Jelen Ted G.
Published: July 2014

The subjective correlates of abortion attitudes for six different religious traditions (Roman Catholicism, Protestantism, Eastern Orthodoxy, Buddhism, Hinduism, and Islam). For all six groups, attitudes toward sexual morality exhibit the strongest relationship with abortion attitudes, followed by the effects of attitudes toward human life. Gender role attitudes are much less powerful predictors of abortion attitudes. Further, the multivariate models which explain abortion attitudes are remarkably similar across religious traditions, with inter-religious differences largely being attributable to differences in the marginal distributions of the independent variables.
DJ-1 interactions with α-synuclein attenuate aggregation and cellular toxicity in models of Parkinson’s disease
Authors: Zondler L , Miller-Fleming L , Repici M , Gonçalves S , Tenreiro S , Rosado-Ramos R , Betzer C , Straatman K R , Jensen P H , Giorgini F , Outeiro T F
Published: July 2014

Parkinson’s disease (PD) is a devastating neurodegenerative disorder characterized by the loss of neurons in the substantia nigra pars compacta and the presence of Lewy bodies in surviving neurons. These intracellular protein inclusions are primarily composed of misfoldedα-synuclein (aSyn), which has also been genetically linked to familial and sporadic forms of PD. DJ-1 is a small ubiquitously expressed protein implicated in several pathways associated with PD pathogenesis. Although mutations in the gene encoding DJ-1 lead to familial early-onset PD, the exact mechanisms responsible for its role in PD pathogenesis are still elusive. Previous work has found that DJ-1 – which has protein chaperone-like activity – modulates aSyn aggregation. Here, we investigated possible physical interactions between aSyn and DJ-1 and any consequent functional and pathological relevance. We found that DJ-1 interacts directly with aSyn monomers and oligomersin vitro, and that this also occurs in living cells. Notably, several PD-causing mutations in DJ-1 constrain this interaction. In addition, we found that overexpression of DJ-1 reduces aSyn dimerization, whereas mutant forms of DJ-1 impair this process. Finally, we found that human DJ-1 as well as yeast orthologs of DJ-1 reversed aSyn-dependent cellular toxicity inSaccharomyces cerevisiae. Taken together, these data suggest that direct interactions between DJ-1 and aSyn constitute the basis for a neuroprotective mechanism and that familial mutations in DJ-1 may contribute to PD by disrupting these interactions.
Microbial degradation of isosaccharinic acid at high pH
Authors: Bassil Naji M , Bryan Nicholas , Lloyd Jonathan R
Published: July 2014

Intermediate-level radioactive waste (ILW), which dominates the radioactive waste inventory in the United Kingdom on a volumetric basis, is proposed to be disposed of via a multibarrier deep geological disposal facility (GDF). ILW is a heterogeneous wasteform that contains substantial amounts of cellulosic material encased in concrete. Upon resaturation of the facility with groundwater, alkali conditions will dominate and will lead to the chemical degradation of cellulose, producing a substantial amount of organic co-contaminants, particularly isosaccharinic acid (ISA). ISA can form soluble complexes with radionuclides, thereby mobilising them and posing a potential threat to the surrounding environment or ‘far field’. Alkaliphilic microorganisms sampled from a legacy lime working site, which is an analogue for an ILW-GDF, were able to degrade ISA and couple this degradation to the reduction of electron acceptors that will dominate as the GDF progresses from an aerobic ‘open phase’ through nitrate- and Fe(III)-reducing conditions post closure. Furthermore, pyrosequencing analyses showed that bacterial diversity declined as the reduction potential of the electron acceptor decreased and that more specialised organisms dominated under anaerobic conditions. These results imply that the microbial attenuation of ISA and comparable organic complexants, initially present or formed in situ, may play a role in reducing the mobility of radionuclides from an ILW-GDF, facilitating the reduction of undue pessimism in the long-term performance assessment of such facilities.
Simultaneous multiplexed quantification of nicotine and its metabolites using surface enhanced Raman scattering
Authors: Alharbi Omar , Xu Yun , Goodacre Royston
Published: July 2014

We have developed a SERS approach that can simultaneously detect the drug nicotine along with its two major metabolites cotinine andtrans-3′-hydroxycotinine without recourse to lengthy chromatography.
Detection of strep throat causing bacterium directly from medical swabs by touch spray-mass spectrometry
Authors: Jarmusch Alan K. , Pirro Valentina , Kerian Kevin S. , Cooks R. Graham
Published: July 2014

The underlying science and initial stages of development of a non-invasive diagnostic technique for strep throat based on ambient ionization mass spectrometry are detailed.
The design and synthesis of an innovative octacarboxy-silsesquioxane building block
Authors: Shanmugan Swaminathan , Cani Damiano , Pescarmona Paolo P.
Published: July 2014

A novel silsesquioxane compound characterised by eight carboxyl groups organised in a cubic symmetry was prepared by a multi-step regioselective synthesis. This compound displays highly attractive chemical and geometrical features for application as a building block in self-assembly processes.
Efficient optical resolution of water-soluble self-assembled tetrahedral M4L6 cages with 1,1′-bi-2-naphthol
Authors: Wan Shigang , Lin Li-Rong , Zeng Lili , Lin Yiji , Zhang Hui
Published: July 2014

Self-assembled tetrahedral M4L6 cages were successfully resolved into their ΔΔΔΔ and ΛΛΛΛ enantiomers by (R)-/(S)-1,1′-bi-2-naphthol.
Facile construction of functionalized periodic mesoporous organosilica for Ir-catalyzed enantioselective reduction of α-cyanoacetophenones and α-nitroacetophenones
Authors: Chen Chen , Kong Lingyu , Cheng Tanyu , Jin Ronghua , Liu Guohua
Published: July 2014

A facile construction of organoiridium-functionalized periodic mesoporous organosilica and its application in the enantioselective reduction of α-cyano and α-nitroacetophenones are studied.
A lipophilic “fully-anti” dodecamer from a (5′S)-5′,8-cyclo-2′-deoxyguanosine
Authors: Pieraccini Silvia , Terzidis Michael A. , Baldassarri Enrico J. , Fragneto Giovanna , Mariani Paolo , Masiero Stefano , Chatgilialoglu Chryssostomos
Published: July 2014

The self-assembly of a lipophilic derivative of mutagenic (5′S)-5′,8-cyclo-2′-deoxyguanosine has been investigated by CD, NMR and SANS. The derivative forms a dodecameric G-quadruplex composed of three stacked fully-anti G-quartets.
Photo-induced glycosylation using reusable organophotoacids
Authors: Iwata Ryosuke , Uda Kanjiro , Takahashi Daisuke , Toshima Kazunobu
Published: July 2014

The glycosylation reactions of glycosyl trichloroacetimidates and several alcohols using an organophotoacid as an activator under photoirradiation proceeded smoothly to give the corresponding glycosides in high yields.
Cyclopropanation of styrenes and stilbenes using lithiomethyl trimethylammonium triflate as methylene donor
Authors: Sarria Toro Juan M. , den Hartog Tim , Chen Peter
Published: July 2014

Soluble lithiomethyl trimethylammonium triflate can cyclopropanate styrenes and stilbenes efficiently. Kinetic experiments support a carbolithiation-ring closure mechanism.
The crystallographic observation of mesitylene–mesitylene and mesitylene–CH2Cl2–mesitylene adducts trapped in an irregular cavity
Authors: Chen Yu , Ma Li , Bian Zheng , Jin Rizhe , Kang Chuanqing , Li Zongjun , Gao Xiang , Han Fushe , Qiu Xuepeng , Gao Lianxun
Published: July 2014

The mesitylene–mesitylene and mesitylene–CH2Cl2–mesitylene adducts can be trapped in the inert cavities. The sp3-CH–π interaction models of these two adducts in the irregular accumulation environment are directly observed.
1D water chain stabilized by meso-expanded calix[4]pyrrole
Authors: Sathish Kumar B. , Panda Pradeepta K.
Published: July 2014

A new core expanded calix[4]pyrrole is reported, in which the opposite bridging sp3-carbons are replaced by ethylene moieties.
Gas-phase electrophilic aromatic substitution mechanism with strong electrophiles explained by ab initio non-adiabatic dynamics
Authors: Kinzel Daniel , Zilberg Shmuel , González Leticia
Published: July 2014

Ultrafast single electron transfer producing a radical pair governs the formation of a σ-complex in gas-phase electrophilic aromatic substitution reactions.
A Bowknot-like RuO2 quantum dots@V2O5 cathode with largely improved electrochemical performance
Authors: Wei Xiujuan , An Qinyou , Wei Qiulong , Yan Mengyu , Wang Xuanpeng , Li Qidong , Zhang Pengfei , Wang Bolun , Mai Liqiang
Published: July 2014

A Bowknot-like RuO2 quantum dots@V2O5 cathode exhibits superior rate capability and cycling stability.
β-Phenyl quenching of 9-phenylphenalenones: a novel photocyclisation reaction with biological implications
Authors: Bucher Götz , Bresolí-Obach Roger , Brosa Carme , Flors Cristina , Luis Javier G. , Grillo Teresa A. , Nonell Santi
Published: July 2014

β-Phenyl quenching of 9-phenylphenalenones leads to the reversible formation of naphthoxanthenes and eventually to stable naphthoxanthenyl radicals or naphthoxanthenium cations.
Constructing atomic layer g-C3N4–CdS nanoheterojunctions with efficiently enhanced visible light photocatalytic activity
Authors: Lu Meiliang , Pei Zengxia , Weng Sunxian , Feng Wenhui , Fang Zhibin , Zheng Zuyang , Huang Mianli , Liu Ping
Published: July 2014

CdS nanoparticles were grown in situ on atomic layer g-C3N4 to form nanoheterojunctions. The synergic effect between CdS and atomic layer g-C3N4 plays a pivotal role for improving the photoactivity.
Copper-catalyzed hydrophosphinations of styrenes in water at room temperature
Authors: Isley Nicholas A. , Linstadt Roscoe T. H. , Slack Eric D. , Lipshutz Bruce H.
Published: July 2014

Copper-catalyzed hydrophosphinations of styrenyl systems in water, at room temperature is herein reported, enabled by our ‘designer’ surfactant TPGS-750-M.
Isolation of a uranium(iii) benzophenone ketyl radical that displays redox-active ligand behaviour
Authors: Matson Ellen M. , Kiernicki John J. , Anderson Nickolas H. , Fanwick Phillip E. , Bart Suzanne C.
Published: July 2014

The first uranium(iii) charge separated ketyl radical complex, Tp*2U(OC·Ph2), has been isolated and acts as a potent two-electron reductant with reducing equivalents derived from both uranium and the redox-active benzophenone.
New members of fluorescent 1,8-naphthyridine-based BF2 compounds: selective binding of BF2 with terminal bidentate N^N^O and N^C^O groups and tunable spectroscopy properties
Authors: Du Mei-Ling , Hu Chun-Yan , Wang Liu-Fang , Li Cong , Han Yang-Yang , Gan Xin , Chen Yong , Mu Wei-Hua , Huang Michael L. , Fu Wen-Fu
Published: July 2014

Selective binding of the BF2 core with N^N(C)^O groups of 1,8-naphthyridine-based compounds produces complexes with tunable absorption and luminescence properties.
The properties and performance of a pH-responsive functionalised nanoparticle
Authors: Ast Sandra , Rutledge Peter J. , Todd Matthew H.
Published: July 2014

We report fluorescence measurements of three quantum dots (QDs) of different sizes functionalised with the same pH responsive naphthalimide dye. QD size strongly influences energy transfer between dye and dot. Using QDs with an emission maximum of 570 nm gives rise to an interesting transfer of energy from dye to dot, while QDs with an emission maximum at 670 nm give unexpected enhancement of the dye emission. Titrations of QDs with the dye provide a means to establish the loading and hence an approximation of the surface dye density, which varies in proportion to QD size. Quenching effects are observed beyond the loading limit, and may indicate non-specific interactions between the excess dye and the nanoparticle. Attachment of the dye to the QD core is achieved by a thiol/disulfide exchange process that has been interrogated with Raman spectroscopy. The stability of these QD–dye conjugates over time and across a physiological pH range has been investigated to provide an assessment of their performance and robustness.
In situ TEM study of the Li–Au reaction in an electrochemical liquid cell
Authors: Zeng Zhiyuan , Liang Wen-I. , Chu Ying-Hao , Zheng Haimei
Published: July 2014

We study the lithiation of a Au electrode in an electrochemical liquid cell using transmission electron microscopy (TEM). The commercial liquid electrolyte for lithium ion batteries (1 M lithium hexafluorophosphate LiPF6 dissolved in 1 : 1 (v/v) ethylene carbonate (EC) and diethyl carbonate (DEC)) was used. Three distinct types of morphology change during the reaction, including gradual dissolution, explosive reaction and local expansion/shrinkage, are observed. It is expected that significant stress is generated from lattice expansion during lithium–gold alloy formation. There is vigorous bubble formation from electrolyte decomposition, likely due to the catalytic effect of Au, while the bubble generation is less severe with titanium electrodes. There is an increase of current in response to electron beam irradiation, and electron beam effects on the observed electrochemical reaction are discussed.
In situ assembly of well-dispersed Ni nanoparticles on silica nanotubes and excellent catalytic activity in 4-nitrophenol reduction
Authors: Zhang Shenghuan , Gai Shili , He Fei , Ding Shujiang , Li Lei , Yang Piaoping
Published: July 2014

Ni nanoparticle/silica nanotube composites with small particle size, good dispersion and high loading amount of Ni NPs was synthesized using an in situ thermal decomposition and reduction strategy. The composite exhibited high catalytic activity and good stability in 4-NP reduction.
Highly efficient graphene-based Cu(In, Ga)Se2 solar cells with large active area
Authors: Yin Ling , Zhang Kang , Luo Hailin , Cheng Guanming , Ma Xuhang , Xiong Zhiyu , Xiao Xudong
Published: July 2014

A high efficiency (13.5%) graphene-based CIGS solar cell with a large active area (45 mm2) is present.
Nucleation and nonisothermal crystallization kinetics in cross-linked polyethylene/zinc oxide nanocomposites
Authors: Jose Josmin P. , Chazeau Laurent , Cavaillé Jean-Yves , Varughese K. T. , Thomas Sabu
Published: July 2014

In the present study organic–inorganic hybrid nanocomposites of cross-linked polyethylene (XLPE) with 0, 2, 5 and 10 wt% of trimethoxyoctyl-silane surface treated ZnO nanoparticles were prepared by melt mixing.
Chiral sensing for electrochemical impedance spectroscopy recognition of lysine enantiomers based on a nanostructured composite
Authors: Huang Yihan , Guo Dongmei , Zhang Qing , Guo Liju , Chen Ya , Fu Yingzi
Published: July 2014

A simple and reliable chiral sensing platform for enantioselective recognition of lysine (Lys) enantiomers based on a nanostructured composite (NC) via the electrochemical impedance spectroscopy (EIS) technique was described.
Highly ordered 2D microgel arrays: compression versus self-assembly
Authors: Geisel Karen , Richtering Walter , Isa Lucio
Published: July 2014

A microgel monolayer at the oil–water interface is prepared using two adsorption methods and visualized by cryo-SEM and AFM methods. Hexagonal microgel arrays of different degrees of ordering are gained.
Solvent induced helical aggregation in the self-assembly of cholesterol tailed platinum complexes
Authors: Mao Yueyuan , Liu Keyin , Meng Luyan , Chen Liang , Chen Liming , Yi Tao
Published: July 2014

Gelation and solvent triggered helical aggregation were reported in the self-assembly of cholesterol tailed platinum complexes.
Synthesis of colloidal microgels using oxygen-controlled flow lithography
Authors: An Harry Z. , Eral H. Burak , Chen Lynna , Chen Michelle B. , Doyle Patrick S.
Published: July 2014

We report the synthesis of non-spherical, Brownian microparticles with sub-micron height using a modified flow lithography technique.
Chaperone turns gatekeeper: PCBP2 and DMT1 form an iron-transport pipeline
Authors: Lane Darius J. R. , Richardson Des R.
Published: July 2014

How is cellular iron (Fe) uptake and efflux regulated in mammalian cells? In this issue of the Biochemical Journal, Yanatori et al. report for the first time that a member of the emerging PCBP [poly(rC)-binding protein] Fe-chaperone family, PCBP2, physically interacts with the major Fe importer DMT1 (divalent metal transporter 1) and the Fe exporter FPN1 (ferroportin 1). In both cases, the interaction of the Fe transporter with PCBP2 is Fe-dependent. Interestingly, another PCBP Fe-chaperone, PCBP1, does not appear to bind to DMT1. Strikingly, the PCBP2–DMT1 interaction is required for DMT1-dependent cellular Fe uptake, suggesting that, in addition to functioning as an intracellular Fe chaperone, PCBP2 may be a molecular ‘gate- keeper’ for transmembrane Fe transport. These new data hint at the possibility that PCBP2 may be a component of a yet-to-be-described Fe-transport metabolon that engages in Fe channelling to and from Fe transporters and intracellular sites.
Colour correction of stereo images using local correspondence
Authors: Lee Yong‐Ho , Lee In‐Kwon
Published: July 2014

A method for enhancing the accuracy of colour correction in stereo images is proposed. The goal is to perform colour compensation at the corresponding points in a stereo image pair using local correspondence information. First, the relevant matching points for colour transfer are extracted using a modified stereo matching algorithm. Then, in order to account for illumination variations and occlusion areas, a new colour transfer method is applied through the weighted sum of the colour difference using local features. The performance of the proposed algorithm has been tested on the reference colour‐modified Middlebury dataset.
Multi‐quantum well Ga(AsBi)/GaAs laser diodes with more than 6% of bismuth
Authors: Butkutė R. , Geižutis A. , Pačebutas V. , Čechavičius B. , Bukauskas V. , Kundrotas R. , Ludewig P. , Volz K. , Krotkus A.
Published: July 2014

Single‐ and multi‐quantum well (QW) structures of Ga(AsBi)/GaAs with up to 10% Bi were grown by molecular beam epitaxy (MBE) at 300–330°C substrate temperature. The photoluminesce measurements of QW structures demonstrated room temperature emission up to wavelengths of ∼1.43 μm. In the structures obtained using a combined growth approach – an active layer with three QWs with ∼6% Bi was grown by MBE, whereas (AlGa)As claddings were grown by the metal organic vapour phase epitaxy technique – room temperature lasing at 1060 nm was documented.
Setpoint control of networked systems via static output feedback integral controller
Authors: Pang Zhong‐Hua , Liu Guo‐Ping , Zhou Donghua
Published: July 2014

This study studies the problem of setpoint output tracking for networked control systems with network‐induced delay, packet disorder and packet dropout. Based on the input–output difference equation model, a novel networked predictive control (NPC) method via static output feedback integral controller (SOFIC) is proposed to actively compensate for the round‐trip time (RTT) delay resulting from the aforementioned communication constraints. It is analysed that the resulting NPC system can achieve a similar tracking performance as that of the corresponding local control system. Based on the performance analysis, a necessary and sufficient condition for the stability of the closed‐loop NPC system is obtained, which is independent of the RTT delay. Both numerical simulations and practical experiments on an internet‐based servo motor system illustrate the effectiveness of the proposed method.
Regression‐based control of thyristor‐controlled series compensators for optimal usage of transmission capacity
Authors: Yang Rui , Hug‐Glanzmann Gabriela
Published: July 2014

Flexible AC transmission system devices provide the opportunity to improve the usage of the current transmission facilities by controlling network flows and nodal voltages. The optimal steady‐state settings of these devices can be determined using optimal power flow calculations. However, this requires knowledge of the system parameters, generation settings and loads. A two‐stage regression‐based control scheme is proposed to determine the optimal settings of thyristor‐controlled series compensators (TCSCs) with the objective to optimally utilise the current transmission system in the presence of renewable energy resources. A regression function describing the relationship between a set of key measurements and the optimal device settings is determined in the offline simulation. This function is then used to calculate the optimal device settings by only receiving the information from a limited number of key measurements without solving the OPF problem in the online operation. Studies are carried out with TCSCs in three‐test systems, the IEEE 14‐bus system, a 28‐bus system and the IEEE 118‐bus system. The simulation results with one, two and four TCSCs are presented, illustrating the performance of the proposed regression‐based control scheme.
Improvement of unified power quality conditioner performance with enhanced resonant control strategy
Authors: Trinh Quoc‐Nam , Lee Hong‐Hee
Published: July 2014

This study proposes an enhanced resonant control strategy for the unified power quality conditioner (UPQC) to simultaneously tackle voltage sags, unbalance and distortions on the supply side as well as current harmonics on the load side. The proposed control strategy is developed in both the series and shunt active power filters (APFs) of the UPQC. In the series APF, a proportional–resonant controller and a resonant controller are employed to mitigate voltage sags, unbalance and distortions, whereas a proportional–integral (PI) controller and three vector PI controllers are used in the shunt APF to compensate harmonic currents. The performance of the proposed UPQC control scheme is significantly improved compared with the conventional control strategy owing to the superiority of the resonant controllers. In addition, voltage sag/harmonic and current harmonic detectors are not required in the proposed control scheme, which helps to simplify the control strategy and to improve the control accuracy. The proposed control strategy is theoretically analysed and its feasibility is validated through experiments.
Power system small‐signal stability region calculation method based on the guardian map theory
Authors: Ma Jing , Wang Shangxing , Wang Zengping , Thorp James S.
Published: July 2014

In view of the potential problems in the system such as sustained oscillation and low damping ratio, which are not considered in traditional small‐signal stability region (SSSR), an improved SSSR (ISSSR) calculation method based on the guardian map is proposed. First, according to the map theory, the system is mapped from the ISSSR to the negative half‐plane. Then by direct sum operation the guardian map is constituted. Finally, the guardian map approach, which is able to solve the exact stability region of the Hurwitz matrix, is used for fast and accurate calculation of the boundary of ISSSR. Simulation tests on the IEEE 4‐machine 11‐node system and 16‐machine 68‐node system verify the correctness and effectiveness of the proposed method. Besides, the influence of the generator excitation system parameters on the ISSSR is also analysed, which is highly valuable in system dispatching instruction and small disturbance instability prevention.
Neighbourhood sensitive preserving embedding for pattern classification
Authors: Wang Bing‐Hui , Lin Chuang , Zhao Xue‐Feng , Lu Zhe‐Ming
Published: July 2014

Recently, a large family of supervised or unsupervised manifold learning algorithms that stem from statistical or geometrical theory has been designed to solve the problem of pattern classification. In this study, consider the fact that the data are usually sampled from a low‐dimensional manifold space which resides in a high‐dimensional Euclidean space, the authors propose a novel two‐graph‐based supervised linear classification algorithm called neighbourhood sensitive preserving embedding (NSPE). Different from local linear embedding (LLE) (or neighbourhood preserving embedding (NPE)) which preserves the local neighbourhood structure with one graph, NSPE can discover both the intrinsic and discriminant structure of the data manifold by constructing two graphs, that is, the within‐class graph and the between‐class graph. Thus, the data are mapped into a subspace where the nearby points with the same label are close to each other, whereas the nearby points with different labels are far apart. As a classification method, besides being defined on training samples, NSPE is also defined on testing samples. Experiments carried on the real‐world face databases demonstrate that the results of all two‐graph‐based spectral methods are comparable and better than that of one‐graph‐based methods.
Computing journey start times with recurrent traffic conditions
Authors: Kala Rahul , Warwick Kevin
Published: July 2014

In this study, the authors discuss the effective usage of technology to solve the problem of deciding on journey start times for recurrent traffic conditions. The developed algorithm guides the vehicles to travel on more reliable routes that are not easily prone to congestion or travel delays, ensures that the start time is as late as possible to avoid the traveller waiting too long at their destination and attempts to minimise the travel time. Experiments show that in order to be more certain of reaching their destination on time, a traveller has to leave early and correspondingly arrive early, resulting in a large waiting time. The application developed here asks the user to set this certainty factor as per the task in hand, and computes the best start time and route.
Interaction design of automatic steering for collision avoidance: challenges and potentials of driver decoupling
Authors: Heesen Matthias , Dziennus Marc , Hesse Tobias , Schieben Anna , Brunken Claas , Löper Christian , Kelsch Johann , Baumann Martin
Published: July 2014

Studies concerning collision avoidance show that most drivers tend to brake, even if evasive manoeuvres were better. Automatic steering for collision avoidance would help here. Studies in the EU project interactIVe observed that drivers show a tendency to hold the steering wheel and disturb the automatic steering when kept in the control loop. A strategy of driver decoupling, for example, by means of steer‐by‐wire systems could improve the automatic steering performance. However, the major challenge of using steer‐by‐wire systems is to enable the driver to compensate false system activation, for example, evasion into oncoming traffic. A time‐dependent strategy of driver decoupling using steer‐by‐wire combined with override recognition by counter steering above a certain threshold was implemented in a research vehicle. The interaction strategy was tested with 45 participants on a test track in two different scenarios; a collision situation with justified evasion and a false alert scenario with unjustified system activation. In a between‐subject design the decoupling strategy (using steer‐by‐wire) was compared against automatic steering with fully coupled driver and force feedback on the steering wheel and against Manual Driving without automatic steering. When the driver was temporarily decoupled, the obstacle avoidance performance was better but the driver was less able to counteract a false avoidance manoeuvre. The analysis of driver behaviour revealed options to improve the interaction strategy.
Broadband and high gain waveguide‐fed slot antenna array in the Ku‐band
Authors: Guan‐Long Huang , Shi‐Gang Zhou , Tan‐Huat Chio , Tat‐Soon Yeo
Published: July 2014

A broadband and high‐gain slot antenna array operating in the Ku‐band is reported in this study. The antenna is with waveguide‐fed cavity backed configuration and made entirely via simple milling process. The overall antenna structure consists of four layers. The bottom layer is a waveguide feed network to provide corporate power division. In turn, the waveguide feed network is excited by a conventional coaxial probe from the back. The waveguide network couples energy to an array of cavity via an aperture plate. These constitute the middle two layers. Each cavity then excites a subarray of 2 × 2 radiating slots in the top layer. The radiating slot elements and the feed network are designed to achieve wide bandwidth and high‐gain performance. Finally, an 8 × 8 array antenna has been designed and fabricated with about 25 dBi gain over 14.8% bandwidth, and the cross‐polarisation was around −30 dB in the boresight.
Single‐pole multiple‐throw switches with defected ground structure low‐pass filter
Authors: Alit Apriyana Anak Agung , Zhang Yue Ping , Chang Joseph S. , Lim Wei Meng
Published: July 2014

In this study, the authors present a novel concept for the design of single‐pole multiple‐throw (SPMT) switches using defected ground structure low‐pass filter (DGS LPF). The DGS LPF produces enhanced inductance to compensate the parasitic capacitance of the control transistors. As a result, the SPMT switch will consume much less silicon area. The concept is experimentally validated with a single‐pole double‐throw (SPDT) switch and a single‐pole four‐throw (SP4T) switch in 65‐nm CMOS. The active area of the SPDT and SP4T switches are less than 130 × 150 μm2 and 180 × 165 μm2, respectively.
Folding method for bandwidth and directivity enhancement of meandered loop ultra‐high frequency antenna for heart failure detection system
Authors: Rezaeieh Sasan Ahdi , Bialkowski Konstanty S. , Abbosh Amin M.
Published: July 2014

A wideband antenna with unidirectional radiation is designed for lower ultra‐high frequency (UHF) band, which is utilised in medical diagnostic systems, in addition to telecommunications, such as UHF television channels, WiMax, cognitive radio, radio frequency identiﬁcation, mobile digital TV and CDMA/GSM800. In medical imaging, there are additional antenna design requirements, such as compact size, wide operating bandwidth and unidirectional radiation. A combination of dual monopole feeding, meandering and folding techniques is used to realise the required frequency band and directivity for the antenna, while reducing its size. The final design has the compact size of 0.23λ × 0.08λ × 0.08λ (λ is the wavelength of the lowest measured operating frequency of the antenna), a wide measured operating bandwidth of 50% (590–985 MHz), a peak gain of 3.6 dBi and a measured efficiency of more than 89% over the band of operation. The designed antenna is then used with a compact microwave transceiver, and proper data acquisition and processing algorithms to build a system for the early detection of congestive heart failure. The system is tested using a realistic artificial human torso.
Economics of customer's decisions in smart grid
Authors: Misra Sudip , Bera Samaresh , Obaidat Mohammad S.
Published: July 2014

In this study, the authors study the problem of allowing customers to use their storage energy, grid energy, as well as privately owned renewable sources of energy. The customer has three options – grid, storage and self‐generated energy, to fulfill the energy requirements. The grid decides real‐time price to maximise its revenue, while ensuring customers’ participation depending on three factors – ‘demand’, ‘supply’ and ‘time of use’. On the other hand, a customer needs to choose strategies on his/her required energy and associated cost, depending on the storage and self‐generated energy, to maximise the pay‐off. They use Markov decision process (MDP) to design this decision making policy of the customer. In such a MDP‐based decision model, a cost‐effective energy management process is established, and, thus, utility of the customers is maximised. Simulation results show that using the proposed approach, the customers decide the strategies to optimise a trade‐off between energy exchange and associated cost. Thus, the utility for customer is increased approximately 60% with the presence of grid, storage and self‐generated energy sources than that of using only grid and storage energy.
Study and design of a novel three‐phase bridgeless boost power factor correction
Authors: Chen Yong , Dai Wen‐ping , Zhou Jun , Hu Eric
Published: July 2014

A novel three‐phase bridgeless boost power factor correction (PFC) circuit is studied and designed. First, the operating principle of the three‐phase bridgeless boost PFC is analysed. Then, the simulation model of the three‐phase bridgeless boost PFC based on the average current control is given. Finally, the simulations are conducted to demonstrate the validity and feasibility of the theoretical analysis. The simulation results show that the proposed system could realise high input power factor, low input current harmonic and low output voltage ripple, and the experimental results show it is effective and feasible in three‐phase circle.
Energy management by using point of common coupling frequency as an agent for islanded microgrids
Authors: Guo Zhiqiang , Sha Deshang , Liao Xiaozhong
Published: July 2014

This study presents an islanded AC microgrid system composed of distributed generations (DGs) and an energy storage system. The valve‐regulated lead acid battery bank is used as the energy storage device. A non‐linear energy management control strategy is proposed by utilising the point of common coupling (PCC) frequency as an agent for all the constituent units, which avoids any communication lines among the constituent units. Based on the system modelling, the stability criterion for the proposed control strategy has been established. The proposed energy management is effective even when the battery is fully charged and DGs can supply more power than the load consumption. For this extreme situation, all DGs can automatically reduce their output power until the battery works in float charge state. The effectiveness of the proposed strategy is verified by simulation and experimental results.
Cascaded TZ‐source inverters
Authors: Nguyen Minh‐Khai , Lim Young‐Cheol , Park Sung‐Jun , Jung Young‐Gook
Published: July 2014

A new cascaded TZ‐source inverter is proposed to distribute the stresses on the passive components. Compared with the conventional cascaded Z‐source inverter topologies for the same number of transformers and turn ratios, the proposed cascaded inverter uses a high modulation index to produce the same output voltage gain with reduced component count. The inductor and transformer in the network can be combined in the proposed cascaded inverter. Its input current is continuous with low ripple if the DC source is connected directly to the inductor. The operating principles and an analysis of the cascaded TZ‐source inverter are presented, and the proposed inverter is compared with the conventional cascaded Z‐source inverters. Simulation and experiment are conducted with cascaded two‐network and three‐network TZ‐source inverters to produce the same output voltage gain.
Improved autonomous current‐fed push–pull resonant inverter
Authors: Abdolkhani Ali , Hu Aiguo Patrick
Published: July 2014

This study presents an improved autonomous current‐fed push–pull resonant inverter with integrated driving power from the input DC source and zero voltage switching (ZVS) signals from the resonant tank. Unlike the conventional current‐fed inverters, the new inverter can increase the system operating frequency up to MHz while maintaining ZVS operation. Moreover, the primary resonant capacitance can be eliminated by advantageously utilising the output capacitances of the switches for resonance. Both simulation and practical results have demonstrated that the proposed inverter is able to generate high quality resonant currents from kHz to 10 MHz for inductive power transfer, induction heating and other applications where high‐frequency currents or voltages are required.
Linear recursive passive target tracking filter for cooperative sea‐skimming anti‐ship missiles
Authors: Han Seul‐Ki , Ra Won‐Sang , Whang Ick‐Ho , Park Jin Bae
Published: July 2014

This study addresses the passive target tracking problem using the range difference (RD) information measured by sea‐skimming anti‐ship missiles. Apart from the conventional non‐linear filtering approaches, the RD‐based passive target tracking problem is newly formulated within the framework of the recently developed non‐conservative robust Kalman filter (NCRKF). By applying NCRKF, the authors are able to cope with the performance degradation in the process of adopting linear measurement model as well as to determine the desirable missile formation in view of target tracking performance. Moreover, the proposed filter might be adequate for the real‐time multiple‐missile applications for its linear recursive structure. Through the simulations for a typical missile homing scenario, it is shown that the proposed scheme could provide faster convergence rate and better target tracking performance than the previous methods.
Iterative least‐squares‐based wave measurement using X‐band nautical radar
Authors: Huang Weimin , Gill Eric , An Jiaqi
Published: July 2014

In this study, an existing iterative least‐squares (LS) method for determining ocean surface currents from X‐band nautical radar images is modified for extracting ocean wave information from the same data. Within each iterative step, the image spectra samples are classified as containing contributions from fundamental, first‐order and higher harmonic waves or noise. Based on the classification result, a new scheme is proposed to increase the robustness of current estimation. This involves automatically adjusting the first threshold that is used for obtaining an initial guess of the current velocity in the iterative LS method. The proposed wave algorithm directly uses the classified fundamental and first‐order harmonic wave components for wave spectra and parameter retrieval. Unlike previous wave analysis techniques in which a bandpass filter is required to eliminate the non‐wave contributions after the current velocity is obtained, the proposed algorithm simplifies the wave retrieval without such a bandpass filter. Algorithm verification is first conducted by using simulated radar images. Subsequently, the method is applied to field radar data and the results are compared with wave‐buoy measurements. Wave parameters from both types of data show that the modified wave algorithm produces results that are close to those achieved using traditional algorithms.
Effects of K distributed sea clutter and multipath on radar detection of low altitude sea surface targets
Authors: Yang Yong , Feng De‐jun , Wang Xue‐song , Xiao Shun‐ping
Published: July 2014

Sea clutter and multipath scattering affect the detection performance of sea surveillance radar simultaneously when the radar detects low altitude target over the sea. In this study, the effects of K distributed sea clutter and multipath on radar detection performance for low altitude sea surface targets are analysed. First, the probability density function of the multipath power propagation factor is derived by taking specular and diffuse reflections into account. Based on this, mathematical expressions of radar detection and false alarm probabilities in K distributed sea clutter and multipath are further derived. The radar detection performances in various K distributed sea clutter and multipath circumstances by simulation are presented, and the impacts of K distributed clutter and multipath on radar detection performance are analysed.
Adaptive robust ultra‐tightly coupled global navigation satellite system/inertial navigation system based on global positioning system/BeiDou vector tracking loops
Authors: Xie Fei , Liu Jianye , Li Rongbing , Hang Yijun
Published: July 2014

With the development of global navigation satellite system (GNSS), the GNSS/inertial navigation system (INS) integrated system offers the users better positioning or navigation performance. This paper proposes an adaptive robust ultra‐tightly coupled GNSS/INS system based on a novel vector tracking strategy for combining both global positioning system (GPS) L1 and BeiDou B1 signals’ tracking together. The inherent mechanism of the vector tracking approach has been analysed to describe the relationship between the replica signals and user's dynamic state. Then, an adaptive robust filter is used to gain the accurate estimates of vehicle states when the vehicle is under a weak‐signal or large manoeuvring environment. Finally, the experimental platform is set up using a GPS/BeiDou signal simulator and an inertial measurement unit simulator and the test results show that the proposed ultra‐tightly coupled system can keep the tracking loops from the high dynamic perturbations, which saves the cost time of signal reacquisition. Moreover, the presented adaptive robust ultra‐tightly coupled system can obtain a higher accuracy than Kalman filtering in a simultaneous weak‐signal and large manoeuvring environment.