bluuebunny/crossref_metadata_2025 huggingface dataset:
Using public health scenarios to predict the utility of a national syndromic surveillance programme during the 2012 London Olympic and Paralympic Games
Authors: MORBEY R. A. , ELLIOT A. J. , CHARLETT A. , IBBOTSON S. , VERLANDER N. Q. , LEACH S. , HALL I. , BARRASS I. , CATCHPOLE M. , McCLOSKEY B. , SAID B. , WALSH A. , PEBODY R. , SMITH G. E.
Published: August 2013

During 2012 real-time syndromic surveillance formed a key part of the daily public health surveillance for the London Olympic and Paralympic Games. It was vital that these systems were evaluated prior to the Games; in particular what types and scales of incidents could and could not be detected. Different public health scenarios were created covering a range of potential incidents that the Health Protection Agency would require syndromic surveillance to rapidly detect and monitor. For the scenarios considered it is now possible to determine what is likely to be detectable and how incidents are likely to present using the different syndromic systems. Small localized incidents involving food poisoning are most likely to be detected the next day via emergency department surveillance, while a new strain of influenza is more likely to be detected via GP or telephone helpline surveillance, several weeks after the first seed case is introduced.
Transcatheter treatment for pulmonary artery occlusion secondary to pulmonary embolism in an infant
Authors: El Tahlawi Mohammad , Assaidi Anass , Fraisse Alain
Published: August 2013

We report a case of successful recanalisation of the left pulmonary artery after occlusion due to embolic thrombi in a 9-month-old infant after surgical repair of a common atrioventricular canal with tetralogy of Fallot. A transhepatic approach was used because of caval vein thrombosis. After the failure of high-pressure balloon angioplasty, the left pulmonary artery was successfully recanalised with cutting balloons, followed by stent implantation with an excellent result.
Pharmacological interventions to modulate attentional bias in addiction
Authors: Luijten Maartje , Field Matt , Franken Ingmar H. A.
Published: August 2013

Attentional bias in substance-dependent patients is the tendency to automatically direct attention to substance-related cues in the environment. Preclinical models suggest that attentional bias emerges as a consequence of dopaminergic activity evoked by substance-related cues. The aim of the current review is to describe pharmacological mechanisms underlying attentional bias in humans and to critically review empirical studies that aimed to modulate attentional bias in substance-dependent patients by using pharmacological agents. The findings of the reviewed studies suggest that attentional bias and related brain activation may be modulated by dopamine. All of the reviewed studies investigated acute effects of pharmacological agents, while measurements of chronic pharmacological treatments on attentional bias and clinically relevant measures such as relapse are yet lacking. Therefore, the current findings should be interpreted as a proof of principle concerning the role of dopamine in attentional bias. At the moment, there is too little evidence for clinical applications. While the literature search was not limited to dopamine, there is a lack of studies investigating the role of non-dopaminergic neurotransmitter systems in substance-related attentional bias. A focus on neurotransmitter systems such as acetylcholine and noradrenaline could provide new insights regarding the pharmacology of substance-related attentional bias.
Impacts of policy measures on the development of state-owned forests in northeast China: theoretical results and empirical evidence
Authors: Jiang Xuemei , Gong Peichen , Bostedt Göran , Xu Jintao
Published: August 2013

State-owned forest enterprises (SOFEs) in northeast China play important roles both in timber production and in the maintenance of ecological security. This paper examines the effects of a number of policy measures on the behavioral choices of the SOFEs. The results show that the extent to which SOFE supervising authorities emphasized the improvement of forest resources in their annual evaluation of the SOFEs had significant impacts on the harvest and investment decisions and the development of forest resources. Promotion of the management and utilization of non-timber resources, as well as reforms aiming to increase the efficiency of forest protection and management, reduced timber harvests and increased investment, which in turn led to improvements of forest resources, although the effects were small. In contrast, reforms aimed at timber harvest and afforestation activities actually contributed to increasing timber harvest, which affected the development of the forest resources negatively.
Greening China's rural energy: new insights on the potential of smallholder biogas
Authors: Christiaensen Luc , Heltberg Rasmus
Published: August 2013

This study assesses a new generation of smallholder biogas, an applied sustainable energy technology currently being rolled out on a massive scale in rural China. In the past, the implementation of biogas programs has been largely disappointing, in China (and elsewhere). User satisfaction with the new program is high, based on purposively collected data from 2,700 households in five provinces, and the available evidence suggests tangible environmental and economic benefits. There are strong indications of fuel switching away from fuelwood and crop residues. Less time is spent on fuelwood collection and cooking, which benefits women especially. Adopters save on fertilizers by using biogas residues. Finally, problems with suspension and interrupted supply appear lower than in earlier studies. Overall, these initial findings are grounds for optimism about the potential for scaled-up smallholder biogas to deliver safe and clean rural energy, in China and beyond, provided critical conditions are met.
Magnified Vision, Mediated Listening and the ‘Point of Audition’ of Early Romanticism
Authors: LOUGHRIDGE DEIRDRE
Published: August 2013

Employing the term ‘point of audition’ to describe the spatial position musical works imply for their listeners, this article examines the use of technologies for extending the senses to define new points of audition in the late eighteenth and early nineteenth centuries. Popular literature on natural philosophy promoted magnifying instruments as windows onto distant or hidden realms and as tools for acquiring knowledge. On the operatic stage and in writers' metaphorical musings, kindred sensory extensions were imagined for hearing. These contexts connected (magic) mirrors and magnifying instruments to their musical analogues: muted tone and keyboard fantasizing. The development of these associations in opera and literature made it possible for instrumental music to position listeners as eavesdroppers upon unknown realms. Such a point of audition is shown to be implied by the Adagio un poco mosso of Beethoven's Fifth Piano Concerto. By examining material practices and discourses surrounding sensory extension, this article demonstrates the relevance of technologically mediated observation to musical culture at the turn of the nineteenth century, and its contribution to the otherworldly orientation characteristic of romantic listening.
SUBDOMINANT RETURNS IN THE VOCAL MUSIC OF J. S. BACH
Authors: ANSON-CARTWRIGHT MARK
Published: August 2013

Bach's vocal oeuvre contains a significant number of movements (about thirty-five), including but not limited to those in modified da capo form, with a concluding reprise of opening thematic material in the subdominant key. Some of these ‘subdominant returns’ involve strict parallelism, whereby the entire A section returns at the new pitch, thus transforming the original ‘departing’ modulation from I to V into a ‘returning’ modulation from IV to I. Many subdominant returns, however, occur in a range of contexts, which resist straightforward formal categorization. One example is the opening chorus from the St Matthew Passion. While the unusual da capo in this movement has elicited provocative commentary by Karol Berger and others in recent years, the significance of the subdominant return (here and elsewhere) has not been examined in depth. This study begins with a comprehensive survey of subdominant returns in Bach's vocal oeuvre, and then examines cyclic and linear aspects of form through detailed analysis of six movements that exhibit this procedure.
Mediale Berichterstattung über den Suizid von Robert Enke
Authors: Teismann Tobias , Schwidder Julia , Willutzki Ulrike
Published: August 2013

Medienberichte über den Suizid prominenter Personen sind mit einem Folgeanstieg der populationsbezogenen Suizidrate assoziiert. Von verschiedenen Organisationen wurden daher Leitfäden für die mediale Berichterstattung über Suizide vorgelegt. In der vorliegenden Untersuchung wurde am Beispiel des Suizids von Robert Enke († 2009) untersucht, inwieweit diese Medienempfehlungen in Deutschland umgesetzt wurden. Analysiert wurden sämtliche Artikel, die im Monat nach Enkes Suizid in zehn der auflagenstärksten deutschen Zeitungen und Zeitschriften publiziert wurden. Insgesamt konnten 169 Artikel identifiziert werden. Die Inhaltsanalyse verweist darauf, dass Medienempfehlungen zur Berichterstattung über Suizide im Fall von Robert Enke nur unzureichend berücksichtigt wurden: 77,5 % der Artikel wiesen mindestens ein Merkmal unangemessener Berichterstattung auf und 51,5 % der Artikel wiesen kein Merkmal präventiver Berichterstattung auf. Im Rahmen einer Clusteranalyse ließen sich fünf Berichterstattungsmuster identifizieren, die sich in ihrer inhaltlichen Ausrichtung und im Ausmaß, in dem präventive Inhalte präsentiert werden, deutlich voneinander unterscheiden. Berichte in der Boulevardpresse unterschieden sich nur geringfügig von Artikeln in anderen Zeitungen. Praktische Implikationen des Befundmusters werden diskutiert.
Gesundheitsförderung von Menschen mit intellektueller Behinderung
Authors: Brehmer-Rinderer Barbara , Weber Germain
Published: August 2013

Zahlreiche Publikationen belegen, dass die Gesundheit von Menschen mit intellektueller Behinderung (IB) für Krankheiten und Störungen anfälliger ist als die der Allgemeinbevölkerung. Zudem sind bestimmte Risikoverhaltensweisen (z. B. schlechte Ernährung und wenig Bewegung) häufiger bei dieser Personengruppe zu finden. Trotz der sensibleren Gesundheitssituation steht die gesundheitspsychologische Forschung für Menschen mit IB noch am Anfang. Für diesen Überblicksartikel wurde Fachliteratur über Menschen mit IB nach gesundheitspsychologischen Konzeptionen durchsucht und bestehende Forschungsarbeiten analysiert. Des Weiteren wurden rezente Gesundheitsmodelle sowie Kontinuitäts- und Stadienmodelle für die Allgemeinbevölkerung und ihre einzelnen Bestandteile hinsichtlich ihrer Übertragbarkeit auf diese spezielle Population untersucht. Eine Generalisierung von Gesundheitsmodellen der Allgemeinbevölkerung auf die Gruppe von Menschen mit IB erscheint aus verschiedenen Gründen problematisch. So erweist sich z. B. die Erfassung einzelner Bestandteile durch ihre Abstraktheit als zu komplex für Menschen mit IB. Dieses und ähnliche Forschungshindernisse werden in diesem Artikel besprochen. Diese genaue Analyse hilft jedoch notwendige Kriterien für die Entwicklung eines theoretischen Gesundheitsmodells speziell für Menschen mit IB zu erstellen. Schlussendlich werden relevante Modellbausteine für Menschen mit IB, die auf den präsentierten Forschungsergebnissen aufbauen, vorgestellt und diskutiert. Schließlich werden zukünftige Forschungsfragen erörtert.
Selective GPER activation decreases proliferation and activates apoptosis in tumor Leydig cells
Authors: Chimento A , Casaburi I , Bartucci M , Patrizii M , Dattilo R , Avena P , Andò S , Pezzi V , Sirianni R
Published: August 2013

We have previously shown that estrogens binding to estrogen receptor (ER) α increase proliferation of Leydig tumor cells. Estrogens can also bind to G protein-coupled ER (GPER) and activation of this receptor can either increase or decrease cell proliferation of several tumor types. The aim of this study was to investigate GPER expression in R2C rat tumor Leydig cells, evaluate effects of its activation on Leydig tumor cell proliferation and define the molecular mechanisms triggered in response to its activation. R2C cells express GPER and its activation, using the specific ligand G-1, is associated with decreased cell proliferation and initiation of apoptosis. Apoptosis after G-1 treatment was asserted by appearance of DNA condensation and fragmentation, decrease in Bcl-2 and increase in Bax expression, cytochrome c release, caspase and poly (ADP-ribose) polymerase-1 (PARP-1) activation. These effects were dependent on GPER activation because after silencing of the gene, using a specific small interfering RNA, cyt c release, PARP-1 activation and decrease in cell proliferation were abrogated. These events required a rapid, however, sustained extracellular regulated kinase 1/2 activation. G-1 was able to decrease the growth of R2C xenograft tumors in CD1 nude mice while increasing the number of apoptotic cells. In addition, in vivo administration of G-1 to male CD1 mice did not cause any alteration in testicular morphology, while cisplatin, the cytotoxic drug currently used for the therapy of Leydig tumors, severely damaged testicular structure, an event associated with infertility in cisplatin-treated patients. These observations indicate that GPER targeting for the therapy of Leydig cell tumor may represent a good alternative to cisplatin to preserve fertility in Leydig tumor patients.
Transcriptional response of bathypelagic marine bacterioplankton to the Deepwater Horizon oil spill
Authors: Rivers Adam R , Sharma Shalabh , Tringe Susannah G , Martin Jeffrey , Joye Samantha B , Moran Mary Ann
Published: August 2013

The Deepwater Horizon blowout released a massive amount of oil and gas into the deep ocean between April and July 2010, stimulating microbial blooms of petroleum-degrading bacteria. To understand the metabolic response of marine microorganisms, we sequenced ∼66 million community transcripts that revealed the identity of metabolically active microbes and their roles in petroleum consumption. Reads were assigned to reference genes from ∼2700 bacterial and archaeal taxa, but most assignments (39%) were to just six genomes representing predominantly methane- and petroleum-degrading Gammaproteobacteria. Specific pathways for the degradation of alkanes, aromatic compounds and methane emerged from the metatranscriptomes, with some transcripts assigned to methane monooxygenases representing highly divergent homologs that may degrade either methane or short alkanes. The microbial community in the plume was less taxonomically and functionally diverse than the unexposed community below the plume; this was due primarily to decreased species evenness resulting from Gammaproteobacteria blooms. Surprisingly, a number of taxa (related to SAR11, Nitrosopumilus and Bacteroides, among others) contributed equal numbers of transcripts per liter in both the unexposed and plume samples, suggesting that some groups were unaffected by the petroleum inputs and blooms of degrader taxa, and may be important for re-establishing the pre-spill microbial community structure.
Self-activation and activation of Cu(0) wire for SET-LRP mediated by fluorinated alcohols
Authors: Samanta Shampa R. , Sun Hao-Jan , Anastasaki Athina , Haddleton David M. , Percec Virgil
Published: August 2013

Herein we report the self-activation and activation of Cu(0) wire used to form a catalyst in single-electron transfer living radical polymerization (SET-LRP) in two fluorinated alcohols employed as solvents, 2,2,2-trifluoroethanol (TFE) and 2,2,3,3-tetrafluoropropanol (TFP).
New statistical model for atmospheric optical scintillation and its application
Authors: Samimi Hossein
Published: August 2013

A generic statistical model, termed Málaga, or M distribution has been proposed recently for the irradiance fluctuations. Based on this model, the irradiance has been written as a product of one term that model large‐scale turbulent effects by a second term that represents the statistically independent small‐scale turbulent effects. The distribution of the small‐scale fluctuations has been derived in terms of the confluent hypergeometric function. The large‐scale fluctuations is widely accepted to be a log‐normal (LN) amplitude, however, to derive a closed‐form expression for the probability density function of the M distribution, it has been modelled by Gamma distribution. It is well‐known that the Gamma distribution is not a good approximation for LN distribution. Hence, in this paper, the inverse Gaussian distribution is proposed, as an alternative to the LN model. It is demonstrated that this substitution gives birth to a new statistical model, termed S distribution, which can be written in a closed‐form expression and makes it possible to model accurately the irradiance fluctuations. To give an application, the performance of a wireless optical heterodyne communication system is investigated over S ‐distributed turbulence channel and closed‐form expression is derived for the average bit error rate of the system.
Design of optical pumping scheme for quantum‐dot semiconductor optical amplifiers
Authors: Taleb Hussein , Abedi Kambiz
Published: August 2013

In this study, design of optical pumping (OP) scheme for quantum‐dot semiconductor optical amplifiers (QD‐SOAs) is investigated. To evaluate the static and dynamic responses of the QD‐SOA under OP, a non‐linear state‐space model is derived in which the effects of the homogeneous and inhomogeneous broadening of the gain medium and the spectral dependence of the input signals are taken into account. Using this model, the effects of the wavelength and power of the pump signal and the homogeneous and inhomogeneous linewidths are studied in detail. Simulation results demonstrate that optimal operation of the QD‐SOA under the OP scheme is realised if the detuning between the pump wavelength and the input signal wavelength is constant (around 100 nm for our investigated device). The authors found that OP scheme can be employed for non‐linear signal processing applications, where the superiorities of the OP against the electrical pumping appear for small values of the homogeneous and inhomogeneous linewidths.
One‐inductor‐based auxiliary circuit for dc‐link capacitor voltage equalisation of diode‐clamped multilevel converter
Authors: Shu Zeliang , Zhu Haifeng , He Xiaoqiong , Ding Na , Jing Yongzi
Published: August 2013

The one‐inductor‐based auxiliary balancing circuit is proposed to equalise dc‐link capacitor voltages of diode‐clamped multilevel converters (DCMC) in this study. After theoretical analysis of balancing unit in traditional one‐level‐based balancing schemes, one‐inductance‐based schemes are designed according to the same operating principle. Via some conducted diodes and switches by simple control, this circuit provides energy exchange paths of all the dc‐link capacitors by only one inductor. Firstly, the inductor absorbs energy from the capacitor with the highest voltage. Then, this capacitor is discharged and its voltage will decrease. Secondly, the inductor releases energy to the capacitor with the lowest voltage. Then, this capacitor is charged and its voltage will increase. After performing this operation a number of times, all the voltages of the dc‐link capacitors will finally reach the same value. The circuit configurations, conducting paths and control strategies of one‐inductor‐based scheme for five‐level DCMC are analysed, respectively. Owing to small equivalent resistances of capacitor and inductor, the small power loss could be achieved. Simulations and experiments have been carried out. The steady‐state and dynamic results verify the effective balancing performance of this circuit.
Capacitor voltage balancing of a three‐phase neutral‐point clamped bi‐directional rectifier using optimised switching sequences
Authors: Hamid Bhat Abdul , Langer Nitin , Sharma Deepak , Agarwal Pramod
Published: August 2013

In this study, a modulation strategy is presented using minimum number of switching transitions of optimised switching sequences for balancing of DC‐bus capacitor voltages of a three‐phase neutral‐point clamped bi‐directional converter. This new approach is derived from the fact that in front end AC–DC converters, the location of supply voltage vector and reference current vector (magnitude and lag angle) vary depending upon the amount of reactive power compensation and the load current to be supplied by converter. Accordingly, the effect of small and medium vectors (using space vector pulse‐width modulation) for same switching state varies in each sector and its regions resulting in DC‐bus capacitor voltage unbalancing. This observation along with the detailed analysis of current pattern for both the capacitors within each sector and its regions and its effect on neutral‐point voltage deviation forms the basis of proposed approach of maintaining optimised space vector sequences and changing the number of sampling periods within each sector and its regions, thus resulting in DC‐bus capacitor voltage balancing. As a result, modified reference current vector spends different amount of time in alternate sectors (moves faster and slower in alternate sectors) but total time for one complete cycle is same as actual current vector. The converter exhibits excellent performance in terms of other critical parameters like unity input power factor, low input current THD, minimum switching losses, reduced ripple factor of the regulated DC output voltage and particularly, the neutral‐point voltage deviation under dynamic load conditions both for rectification and inversion modes of operation.
Modelling and control of a multi‐stage interleaved DC–DC converter with coupled inductors for super‐capacitor energy storage system
Authors: De Dipankar , Klumpner Christian , Patel Chintanbhai , Ponggorn Kulsangcharoen , Rashed Mohamed , Asher Greg
Published: August 2013

Interleaved converters with coupled inductors are widely used to share load current in high power applications. It offers high equivalent switching frequency and reduced output current ripples using small size magnetic components. Owing to smaller common‐mode inductance, control system can be designed to achieve fast dynamic response. This study proposes eight‐channel interleaved DC/DC converter for interfacing super‐capacitor energy storage system to a 400 V DC voltage bus. Multi‐stage interleaving magnetic circuit with two‐phase coupling inductor as a building block is proposed. A methodology is developed to construct the model of the multi‐stage magnetic circuit from the basic two‐phase coupled inductor model. The derived model is successfully used to evaluate the system power losses and to design the magnetic circuit parameters and its current controller to fulfil the DC/DC converter steady state and dynamic performance specifications. A 20 kW/four stage/8‐channel DC/DC converter laboratory prototype has been built to connect a super‐capacitor stack to 400 V DC voltage bus. Experimental investigation validates the modelling, the system losses calculations and the design specifications of the system.
Accurate model for the forward converter with peak current‐mode control
Authors: Chen Shen‐Yuar , Van Manh Tran
Published: August 2013

In this study, an accurate model for the forward converter with peak current‐mode control is clearly shown in order to analyse the effect of the magnetising inductor. From the current loop of the proposed model, it can be found that the magnetising inductor current has the same effect of preventing the converter from sub‐harmonic oscillation as that of the external ramp. In addition, the feed forward gain of the circuit has been modified owing to the effect of the magnetising inductor. Finally, the validity and accuracy of the small‐signal model containing a magnetising inductor are verified with the results of the experiment.
Power flow control of intertied ac microgrids
Authors: Nutkani Inam Ullah , Loh Poh Chiang , Blaabjerg Frede
Published: August 2013

Microgrids are small reliable grids formed by clustering distributed sources and loads together. They can, in principle, operate at different voltages and frequencies like 50, 60, 400 Hz or even dc. Tying them together or to the mains grid for energy sharing would therefore require the insertion of interlinking power converters. Active and reactive power flows of these converters should preferably be managed autonomously without demanding for fast communication links. A scheme that can fulfill the objectives is now proposed, which upon realised, will result in more robustly integrated microgrids with higher efficiency and lower reserve requirement. The scheme presented has been tested in experiments with results captured and discussed in a later section.
Theoretical and experimental evaluation of four space‐vector modulations applied to quasi‐Z‐source inverters
Authors: Liu Yushan , Ge Baoming , Abu‐Rub Haitham
Published: August 2013

There are three existing space‐vector modulation (SVM) methods for three‐phase Z‐source/quasi‐Z‐source inverter (ZSI/qZSI), and a new one can be extended from the existing SVMs. These four SVMs are never compared and evaluated in terms of their performances. This study conducts the theoretical analysis and experimental evaluations of four SVMs. The switching control patterns, the available shoot‐through duty ratio, the boost capability, the maximum voltage stress across the switch, inductor current ripple, total average switch device power, ac output current's harmonic and efficiency are fully addressed in the theoretical and experimental comparisons. A three‐phase qZSI prototype is built to carry out the experimental evaluation. The valuable suggestions are summarised in the conclusion.
Circuitry and analysis of input‐capacitor‐added multiple‐input buck converters
Authors: Xian Liang , Wang Gucheng , Wang Youyi
Published: August 2013

Characterised as more straightforward topology, less components and simpler control, multiple‐input (MI) converters are becoming active to be studied and implemented in renewable energy hybrid systems (REHSs) in the recent decade. In this study, a complete and systematic circuitry analysis of conventional MI buck converter (MIBC) and input‐capacitor‐added (ICA) MIBC topologies is clarified. Proceeded from the derivation of the input current of the utilised power source, a series of general equations of both conventional and ICA MIBCs that describe the circuits’ electrical characteristics and behaviours are deduced, in the form of the kth practical source and considering the influence of equivalent series resistor(s), which are not put forward in previous literatures. The value of k can be any positive integral theoretically. The accuracy of these formulas is verified by comparing with the test results, combined with which, the impacts of the four main circuit parameters on the power sources are also discussed. The introduction of ICA MIBC is aimed at showing its specific capabilities and advantages in applications of REHSs, beyond conventional MIBC topology. The circuitry analysis, the proposed equations and the comparing discussion in this study do practically benefit to theoretical research, industrial application and power budgeting of MIBC.
Pulse density modulated control patterns for inductively powered implantable devices based on energy injection control
Authors: Leung Ho Yan , McCormick Daniel , Budgett David M. , Hu Aiguo Patrick
Published: August 2013

High power inductively powered implantable devices (5–15 W) such as an artificial heart demand continuous power over widely varying coupling and loading conditions. An energy injection converter is suitable for driving the power transfer coil of an inductive power transfer system for this application because of its ability to control power flow over a large coupling range without any additional power stages. In addition it allows this to be done while maintaining soft‐switching at all times. Here the authors propose a new control method based on pulse density modulation patterns. The proposed control is compared with other energy injection control methods, and it is found to have superior performance in terms of control action and linearity. It is also shown to improve the practical control range and decreases the component stress with improved resonant waveforms. The comparison of different control methods was performed through simulation and verified through practical implementation.
Fixed and variable power angle control methods for unified power quality conditioner: operation, control and impact assessment on shunt and series inverter kVA loadings
Authors: Khadkikar Vinod
Published: August 2013

The concept of power angle control (PAC) of unified power quality conditioner (UPQC) provides an effective way to utilise the full capacity of series inverter of UPQC. This study deals with the operation and control of UPQC with PAC under voltage sag and swell conditions. The power angle, a resultant angle between actual source voltage and resultant load voltage, is used as a control variable. Two new control approaches, namely, fixed power angle and variable power angle, are proposed. It is shown that these approaches can affect the overall kVA loadings of shunt and series inverters. A thorough investigation on these fixed and variable power angle methods is presented in this study. A Matlab/Simulink‐based detailed simulation and digital signal processor‐based experimental studies are discussed to evaluate the performance of proposed two methods.
Low‐voltage ride‐through concept in flyback inverter‐based alternating current–photovoltaic modules
Authors: Papanikolaou Nick P.
Published: August 2013

The flyback inverter‐based alternating current–photovoltaic modules’ behaviour under voltage rise/drop conditions is investigated. Specifically, the aim is to calculate the module steady‐state operational characteristics of distributed generators, such us generation loss and root mean square current rise, based on the low‐voltage ride‐through capability requirements. The proposed analysis stands for the widely known discontinuous conduction mode of operation and it can also account for high power inverter topologies. Furthermore, the derived expressions are corroborated by means of PSPICE simulation along with the selected experimental results and insightful discussions.
Parameter extraction of conducted electromagnetic interference prediction model and optimisation design for a DC–DC converter system
Authors: Wang Quandi , An Zongyu , Zheng Yali , Yang Yongming
Published: August 2013

This study aims to establish a prediction model for the conducted interference of a buck converter system and verify the accuracy of the prediction model through experiments. The prediction model considers each component as an equivalent circuit model that is represented by lumped parameters and introduces the parameter extraction method. For the parameter extraction in the power line model, a numerical computation method that combines partial capacity theory (PCT) and finite element method (FEM) is used. For the modelling of the interference source, a concentrated and equivalent method is used to process synthetically the voltage jumps generated by multiple switching devices as one interference voltage source, which serves as an excitation source for the prediction model. Importantly, a computation model for parasitic capacitance is proposed, and a computation process for parasitic parameters that combine the electrostatic field principle and FEM is derived. Besides, this paper analyses the effects of parasitic parameters on impedance, which interferes with the transmission loop; changes the thickness of the thermal conductive adhesive, which are filled between the transistor heat‐conducting plate and heat sink to reduce the conducted interference; verifies the accuracy of the proposed method on reducing electromagnetic interference (EMI) by experiment.
Influence of migratory scattering phenomenon on micro‐motion characteristics contained in radar signals
Authors: Guo Kun‐Yi , Sheng Xin‐Qing , Shen Rong‐Hui , Jing Cong‐Jun
Published: August 2013

The micro‐motion characteristics of radar target are useful features for target recognition. Extended targets (as opposed to point target) have various scattering centres, such as the familiar point, localised and distributed scattering centres, as well as the rarely discussed but often encountered migratory scattering centres. The migratory scattering phenomenon of smooth surface is particularly concerned in this study. The motion information recoded in radar signals are actually that of migratory scattering centres rather than the real motions of the rigid target. Therefore the misleading motion information will bring unpredictable error to the radar application of target discrimination or recognition. To tackle this problem, the influence of migratory scattering phenomena of extended targets on micro‐motion characteristics contained in radar signal is analysed in detail. Some meaningful conclusions are reached. The backscattered signals of extended targets are computed by the well‐validated full‐wave numerical method, hybrid finite element‐boundary integral‐multilevel fast multipole algorithm. The numerical results agree well with the analytical conclusions given in this study.
Detection of low observable moving target in sea clutter via fractal characteristics in fractional Fourier transform domain
Authors: Chen Xiaolong , Guan Jian , He You , Zhang Jian
Published: August 2013

Effective detection of low observable moving target at sea is important for remote sensing and radar signal processing. The non‐Gaussian property of sea clutter and lack of accurate model make the detection difficult for statistics based detectors. Also the fractal techniques in time domain cannot achieve high detection probability in heavy sea clutter. To help solve the problems, fractal characteristics of IPIX datasets in fractional Fourier transform (FRFT) domain are analysed making use of the fluctuation of FRFT amplitudes and moving target detection algorithms are proposed based on the fractal characteristics in FRFT domain. Firstly, fractal model in FRFT domain is established with fractional Brownian motion model and two judgment and extraction methods are employed for calculating the fractal characteristics in FRFT domain. It is found that sea clutter of different polarisations exhibit fractal behaviours in FRFT domain, that is, self‐similarity property, within its corresponding scale‐invariant interval. Then, we find that four specific fractal statistics in the best FRFT domain can provide valuable information for developing simple and effective detectors. Finally, traditional amplitude detector and Hurst exponent detector in time domain are compared and the results prove the superior detection ability of low observable moving target without complex computations.
Covariance matrix estimation via geometric barycenters and its application to radar training data selection
Authors: Aubry Augusto , De Maio Antonio , Pallotta Luca , Farina Alfonso
Published: August 2013

This study deals with the problem of covariance matrix estimation for radar signal processing applications. The authors propose and analyse a class of estimators that do not require any knowledge about the probability distribution of the sample support and exploit the characteristics of the positive‐definite matrix space. Any estimator of the class is associated with a suitable distance in the considered space and is defined as the geometric barycenter of some basic covariance matrix estimates obtained from the available secondary data set. Then, the authors introduce an adaptive detection structure, exploiting the new covariance matrix estimators, based on two stages. The former consists of a data selector screening among the training data, whereas the latter is a conventional adaptive matched filter taking the final decision about the target presence. At the analysis stage, the authors assess the performance of the proposed two‐stage scheme in terms of probability of correct outliers excision, constant false alarm rate behaviour and detection probability. The analysis is conducted both on simulated data and on the challenging KASSPER datacube.
Fuzzy c‐means clustering‐based smart tracking model for three‐dimensional manoeuvring target including unknown acceleration input
Authors: Son Hyun Seung , Park Jin Bae , Joo Young Hoon
Published: August 2013

This study proposes a smart tracking model with multiple structures. To achieve optimal performance, an ideal tracking system should maintain contact with the target and constantly update its tracking data. One of the major problems to consider arises from the target motion uncertainty. Although the variance of the overall noise is time‐varying and may reduce tracking efficiency, it is difficult to adaptively approximate this uncertainty. To solve these computational problems, a variety of techniques have been studied, and the adaptive interacting multiple model has shown the best result. However, predefined sub‐models with different conditions for multiple models are required. Moreover, the acceleration intervals for different acceleration levels should be determined in advance. To alleviate these problems, the authors propose a multiple‐structured smart tracking algorithm which properly separates the acceleration from the overall noise by fuzzy c‐means clustering. The filter in the algorithm recognises the manoeuvring target as if it does not include the acceleration input, and precisely tracks the target with multiple structures. This study focuses on the acceleration causing the uncertainty and three‐dimensional (3D) motion of the real target motion in the tracking problem. Finally, a 3D cruise missile example is provided to show the effectiveness of the proposed algorithm.
Theoretical analysis of the sequential lobing technique for correlated targets
Authors: Cui Guolong , De Maio Antonio , Pallotta Luca , Farina Alfonso
Published: August 2013

This study is focused on the performance analysis of the sequential lobing technique for angle tracking in the presence of correlated fluctuating targets. The evaluation is conducted on the signal at the output of a conventional incoherent receiver followed by a logarithmic amplifier, assuming that the target returns at the two beam positions are correlated random variables. The general expression of the normalised root mean square error of the angular estimate is derived. Then, it is particularised to Swerling I target fluctuation at each of the beam positions. Additionally, assuming high signal‐to‐noise ratio, the probability density function of the angular estimate is provided. Finally, using Monte Carlo techniques, several numerical results are given and the effects of typical values of the correlation coefficient are discussed.
Feature extraction of rotational yargets in wideband T/R–R bistatic radar
Authors: Xiaofeng Ai , Yongzhen Li , Xuesong Wang , Shunping Xiao
Published: August 2013

The rotational radius observed by monostatic radar is modified by the angle between the rotational vector and the radar line of sight. In this study, wideband T/R–R bistatic radar is introduced to estimate the real radius of a rotational scatterer. The geometric relation between the bistatic radar and a rotational scatterer is modelled first. By combining the parameters of the trace of the same rotational scatterer in the mono‐ and bistatic time‐range images, a method based on parameter estimation, scatterer association and equation solving is proposed to estimate the real rotational radius. Finally, the validity of the proposed method is verified by lots of numeric simulations.
Analysis of stroboscopic signal sampling for radar target detectors and range finders
Authors: Bystrov Aleksandr , Gashinova Marina
Published: August 2013

This study considers the influence of signal sampling on the characteristics of target detectors and range finders, which form parts of radar systems. Quasi‐optimal algorithms for target detection and range measurement are analysed, which demonstrate close to optimal performance even if low‐performance signal processing equipment is used. Special attention is given to stroboscopic sampling. In the case of a high signal‐to‐noise ratio, stroboscopic sampling can provide better detection performance than traditional, or real‐time, sampling. The accuracy of range finders with stroboscopic signal sampling is estimated. The considered method allows for a reduction in both instrumental range measurement error and random error of tracking compared with traditional sampling methods, without an increase in requirements of the range finders’ performance.
Stimulation of superconductivity by microwave radiation in wide tin films (Review Article)
Authors: Zolochevskii I. V.
Published: August 2013

The review is devoted to an experimental study of simulation of superconductivity by microwave radiation in superconducting films. An influence of the power, frequency of microwave radiation, as well as temperature and width of superconducting films on behavior of experimental dependencies of stimulated the critical current and the current at which a vortex structure of the resistive state vanishes and the phase-slip first line appears is analyzed. The experimental studies of films with different width reveal that the effect of superconductivity stimulation by microwave field is common and occurs in both the case of uniform (narrow films) and non-uniform (wide films) distribution of superconducting current over the film width. It is shown that stimulation of superconductivity in a wide film increases not only the critical current and the critical temperature, but also the maximum current at which there is a vortex state in the film. The effect of superconductivity stimulation by microwave radiation in wide films can be described by the Eliashberg theory, which was used to explain the same phenomenon in narrow channels. For the first time it was found experimentally that when the film width increases, the range of radiation power, at which the effect of superconductivity stimulation is observed, shrinks abruptly, and hence the probability of its detection decreases.
Temperature dependencies of magnetization in the Co/Cu (111) superlattices
Authors: Kutko K. V. , Bludov A. N. , Savina Yu. A. , Paschenko V. A. , Anders A. G. , Zorchenko V. V. , Stetsenko A. N.
Published: August 2013

It was found that temperature dependencies of magnetization in the Co/Cu (111) superlattices contain ferromagnetic and paramagnetic contributions. Samples of the [Co(8 Å)/Cu(dCu)]20 (dCu = 9–1 Å) series were grown on mica by magnetron sputtering upon a pseudomorphic growth of Co and Cu layers. They have a polycrystalline structure with a grain size of 80–100 Å. Estimates show that the paramagnetic magnetization part is formed by ∼48% of Co atoms contained in a sample. It is assumed that the most probable mechanism of formation of the paramagnetic phase is related to diffusion processes in an interface between grains.
Mechanical properties of the high-entropy alloy Ag0.5CoCrCuFeNi at temperatures of 4.2–300 K
Authors: Laktionova M. A. , Tabchnikova E. D. , Tang Z. , Liaw P. K.
Published: August 2013

The plastic deformation behavior of the high-entropy alloy Ag0.5CoCrCuFeNi produced in an argon-arc melt is studied for the first time at low temperatures (down to 4.2 K). Lowering the temperature from 300 to 4.2 K leads to an increase in the nominal yield strength from 450 to 750 MPa while the degree of plasticity of the alloy remains on the order of 30% over the entire range. The strain rate sensitivity is measured for deformations ε ∼ 2% by strain rate cycling. Assuming thermally activated plasma deformation, the activation volume for movement of dislocations is calculated for ε ∼ 2% and is found to vary from 122b3 at 300 K to 35b3 at 30 K, where b is the Burgers vector.
The streamwise drag-reduction response of a boundary layer subjected to a sudden imposition of transverse oscillatory wall motion
Authors: Lardeau Sylvain , Leschziner Michael A.
Published: August 2013

A direct numerical simulation study is presented, which examines the response of a spatially developing boundary layer to oscillatory spanwise wall motion imposed over a limited streamwise stretch. At the heart of the study is the dependence of the streamwise variations in skin friction and turbulence properties on the period of the oscillatory motion, with particular emphasis placed on the behaviour downstream of the start of the actuation. The friction Reynolds number just upstream of the actuation is Reτ = 520, and the wall-scaled actuation period, T+ = Tuτ2/ν, covers the range 80–200. In contrast to channel flow, the present configuration allows the processes during the transition stretch from the unactuated state to the low-drag state and the recovery from the low-drag state to be studied. Attention focuses primarily on the former. Results are included for the time-averaged turbulent stresses, their budgets and probability-density functions, as well as a range of phase-averaged properties. The study brings out, for low-drag conditions, a number of features and processes that are common with those in actuated channel flow, but suggests that the maximum drag-reduction margins are lower than those in equivalent channel flow, and that the optimum actuation period is significantly shorter. The transition to the low-drag state occurs over about 5 boundary-layer thicknesses, and is characterised by substantial oscillations in all phase-averaged properties. These oscillations, provoked at the start of the spanwise motion, propagate convectively as waves and decay as the low-drag state is approached. The interactions contributing to the oscillations are discussed as part of the analysis of phase-averaged quantities.
On the acoustic radiation of a pitching airfoil
Authors: Manela A.
Published: August 2013

We examine the acoustic far field of a thin elastic airfoil, immersed in low-Mach non-uniform stream flow, and actuated by small-amplitude sinusoidal pitching motion. The near-field fluid-structure interaction problem is analyzed using potential thin-airfoil theory, combined with a discrete vortex model to describe the evolution of airfoil trailing edge wake. The leading order dipole-sound signature of the system is investigated using Powell-Howe acoustic analogy. Compared with a pitching rigid airfoil, the results demonstrate a two-fold effect of structure elasticity on airfoil acoustic field: at actuation frequencies close to the system least stable eigenfrequency, elasticity amplifies airfoil motion amplitude and associated sound levels; however, at frequencies distant from this eigenfrequency, structure elasticity acts to absorb system kinetic energy and reduce acoustic radiation. In the latter case, and with increasing pitching frequency ωp, a rigid-airfoil setup becomes significantly noisier than an elastic airfoil, owing to an \documentclass[12pt]{minimal}\begin{document}$\omega _p^{5/2}$\end{document}ωp5/2 increase of its direct motion noise component. Unlike rigid airfoil signature, it is shown that wake sound contribution to elastic airfoil radiation is significant for all ωp. Remarkably, this contribution contains, in addition to the fundamental pitching frequency, its odd multiple harmonics, which result from nonlinear interactions between the airfoil and the wake. The results suggest that structure elasticity may serve as a viable means for design of flapping flight noise control methodologies.