bluuebunny/crossref_metadata_2025 huggingface dataset:
Ophthalmosaurian (Ichthyosauria) records from the Aalenian–Bajocian of Patagonia (Argentina): an overview
Authors: FERNÁNDEZ MARTA S. , TALEVI MARIANELLA
Published: May 2013

The oldest ophthalmosaurian records worldwide have been recovered from the Aalenian–Bajocian boundary of the Neuquén Basin in Central-West Argentina (Mendoza and Neuquén provinces). Although scarce, they document a poorly known period in the evolutionary history of parvipelvian ichthyosaurs. In this contribution we present updated information on these fossils, including a phylogenetic analysis, and a redescription of ‘Stenopterygius grandis’ Cabrera, 1939. Patagonian ichthyosaur occurrences indicate that during the Bajocian the Neuquén Basin palaeogulf, on the southern margins of the Palaeopacific Ocean, was inhabited by at least three morphologically discrete taxa: the slenderStenopterygius cayi, robust ophthalmosaurianMollesaurus periallusand another indeterminate ichthyosaurian. Rib bone tissue structure indicates that rib cages of Bajocian ichthyosaurs included forms with dense rib microstructure (Mollesaurus) and forms with an ‘osteoporotic-like’ pattern (Stenopterygius cayi).
First occurrence of a phacopid trilobite faunule from the Upper Devonian of Saoura Valley, Algeria and biodiversity fluctuations
Authors: CRÔNIER CATHERINE , MALTI FATIMA ZOHARA , FRANÇOIS ANGELA , BENYOUCEF MADANI , BRICE DENISE
Published: May 2013

Phacopid trilobites are relatively widespread in Devonian deposits of north Gondwana and some have been collected from several sections of the Saoura Valley in SW Algeria. New occurrences of phacopids assigned to Trimerocephalus, Dianops and Phacops sensu lato are described from this area and comparisons are made with closely allied species from Morocco and Europe. The trilobite assemblages of the ‘Argiles de Marhouma’ Formation are considered to be Frasnian–Famennian in age. These new occurrences have been integrated into an analysis of Upper Devonian phacopid biodiversity. Diversity fluctuations reflect environmental changes, bioevents and stratigraphic turnovers throughout the Upper Devonian. Peak diversity was attained after the post-Kellwasser event.
The Emergence of Politico-Religious Groupings in Late Nineteenth-Century Buganda
Authors: Twaddle Michael
Published: May 2013

This article reconsiders the emergence of politico-religious groupings in the kingdom of Buganda in the late nineteenth century, in the light of historical writings and research since 1952. It accepts J. M. Waliggo's view that the Christian martyrdoms of the mid-1880s need to be taken seriously by secular historians as an influence upon later Christian fanaticism. However, the link to later fanaticism was only politically established during the course of the Ganda succession war of 1888–90, when Kalema's establishment of an Islamic state in Buganda prompted the creation of rival Protestant and Roman Catholic politico-religious groupings. The present writer therefore accepts the stress upon the strategic importance of the Ganda Christian martyrs in Roland Oliver's pioneering study of The Missionary Factor in East Africa but questions the view of Oliver (and subsequent historians) that European missionaries were primarily responsible for the emergence of political competition between Anglican and Roman Catholic Christians in Buganda. Nonetheless, when politico-religious groupings did emerge in the kingdom during the succession war of 1888–90, both C.M.S. missionaries and the White Fathers were most important in ensuring that the two rival politico-religious groupings did not abort themselves as a result of Ganda Christian chiefs indulging in inter-personal strife along other lines of cleavage. That, however, is largely a later story, to which Oliver's Missionary Factor still serves as the essential introduction.
NGOs, elite capture and community-driven development: perspectives in rural Mozambique
Authors: Arnall Alex , Thomas David S.G. , Twyman Chasca , Liverman Diana
Published: May 2013

This article examines the problems of elite capture in community-driven development (CDD). Drawing on two case studies of non-governmental organisation (NGO) intervention in rural Mozambique, the authors consider two important variables – (1) the diverse and complex contributions of local elites to CDD in different locations and (2) the roles that non-elites play in monitoring and controlling leader activities – to argue that donors should be cautious about automatically assuming the prevalence of malevolent patrimonialism and its ill-effects in their projects. This is because the ‘checks and balances’ on elite behaviour that exist within locally defined and historically rooted forms of community-based governance are likely to be more effective than those introduced by the external intervener.
‘New agriculture’ for sustainable development? Biofuels and agrarian change in post-war Sierra Leone
Authors: Maconachie Roy , Fortin Elizabeth
Published: May 2013

In sub-Saharan Africa, commercial bioenergy production has been hailed as a new form of ‘green capitalism’ that will deliver ‘win-win’ outcomes and ‘pro poor’ development. Yet in an era of global economic recession and soaring food prices, biofuel ‘sustainability’ has been at the centre of controversy. This paper focuses on the case of post-war Sierra Leone, a country that has over the last decade been consistently ranked as one of the poorest in the world, facing food insecurity, high unemployment and entrenched poverty. Following a recent government strategy to secure foreign direct investment in biofuels production in agriculturally rich regions of the country, the largest foreign investment in Sierra Leone since the end of its civil war has been secured: a Swiss company is to invest US$368 million into a large-scale biofuels project over the course of 3 years, and promises to simultaneously stimulate an enabling environment for investment, provide job opportunities for youth and increase food production. For multiple actors involved in the project, the concept of ‘sustainability’ is crucial but accordingly there are varying interpretations of its meaning. Such differences in interpretation and the complex contradictions within discourses of sustainability are in turn framed by the various scales within which these actors are situated. While attempts have been made to manage these contradictions through global sustainability standards, the unequal power relations between different actors will ultimately determine the ways in which they are likely to be resolved. The paper concludes by reflecting on how these processes may be contributing to a changing governance landscape and wider global political economy within which bioenergy is being produced, processed and consumed.
Mechanisms and effectiveness of prebiotics in modifying the gastrointestinal microbiota for the management of digestive disorders
Authors: Whelan Kevin
Published: May 2013

The gastrointestinal microbiota is a complex ecosystem with each human individual hosting at least 160 different bacterial strains. Our understanding of its role is rapidly expanding as a result of the molecular microbiological techniques that can accurately characterise its composition and ‘omics’ technologies that measure its metabolic activity. Since 1995, extensive research has investigated the prebiotic concept, which describes how supplementation of some non-digestible oligosaccharides can stimulate the growth and/or activity of specific genera including bifidobacteria. However, the vast majority of studies are in healthy human subjects, with few undertaken in patients with disorders relevant to clinical nutrition. Marked alterations of the luminal microbiota have been demonstrated in patients with digestive disorders, highlighting mechanisms through which they might be involved in their pathogenesis, including higher clostridia in patients who develop diarrhoea during enteral nutrition and the influence of bifidobacteria on intestinal dendritic cell phenotype in Crohn's disease. The impact of prebiotics on the intestinal microbiota of healthy people has not been consistently replicated in patients with digestive disorders. For example, a number of studies show that inulin/oligofructose do not increase bifidobacteria in enteral nutrition and Crohn's disease. Indeed, in Crohn's disease and irritable bowel syndrome there is evidence that some prebiotics in high doses worsen functional symptoms. Unlike healthy human subjects, patients experience a number of issues that may alter their gastrointestinal microbiota (disease, antibiotics and inflammation) and the use of microbiota modifying therapies, such as prebiotics, do not always elicit the same effects in patients as they do in healthy people.
Ending it all: Genesis and Revelation
Authors: Hill Sarah
Published: May 2013

Because of their brevity, many pop songs of the last 50 years seemingly elude the application of narrative theory. But the deliberate lengthening of individual tracks during the early years of progressive rock exposes them to precisely that kind of examination. One such song is ‘Supper's Ready’, which closes the 1972 Genesis albumFoxtrot. This allegorical 23-minute epic, abundant with references to the Book of Revelation, provides an intriguing model for the ‘concept song’, and confounds the listener's expectations – lyrical, musical, narrative, structural and temporal. In this article I explore the seven tableaux of ‘Supper's Ready’, paying particular attention to the treatment of the apocalyptic theme, apply formalist and narrative theories of interpretation, and consider ways in which the song's design demands that the listener engage with both its concept and its construction.
Afro-Samurai: techno-Orientalism and contemporary hip hop
Authors: McLeod Ken
Published: May 2013

This article examines the practice and recent rise in the use of various aspects of Japanese popular culture in hip hop, particularly as manifest in the work of RZA, Kanye West and Nicki Minaj. Often these references highlight the high-tech, futuristic aesthetic of much Japanese popular culture and thus resonate with concepts and practices surrounding Afro-futurism. Drawing on various theories of hybridity, this article analyses how Japanese popular culture has informed constructions of African American identity. In contrast to the often sensational media coverage of racial tensions between African American and Asian communities, the nexus of Japanese popular culture and African American hip hop evinces a sympathetic connection based on shared notions of Afro-Asian liberation and empowerment achieved, in part, through a common aesthetic of technological mastery and appropriation. The synthesis of Asian popular culture and African American hip hop represents a globally hybridised experience of identity and racial formation in the 21st century.
Cluster reduction and compensatory lengthening in the acquisition of possessive -s
Authors: MEALINGS KIRI TRENGOVE , DEMUTH KATHERINE
Published: May 2013

Previous research shows that two-year-olds' third person singular -s and plural -s are produced more accurately in utterance-final compared to utterance-medial position. However, only the third person singular is affected by coda complexity. This study explores these effects with possessive -s. Acoustic analysis of twelve two-year-olds' elicited imitations examined the use of simple versus complex codas (e.g. Sue's vs. Doug's) both utterance-medially and utterance-finally. Morpheme production was surprisingly robust across contexts, though coda clusters were often simplified to a lengthened -s morpheme utterance-medially (e.g., Dou's [dɐz]). The findings raise many questions about the development of speech planning processes across populations.
Inspiring Capital? Deconstructing myths and reconstructing urban environments, Edinburgh, 1860–2010
Authors: MADGIN REBECCA , RODGER RICHARD
Published: May 2013

‘Inspiring Capital’ is the sign that confronts visitors and residents alike at the boundaries of the Edinburgh administrative area. It is a consciously ambiguous message of self-promotion: the logo proclaims the dual standing of the city of Edinburgh as a European capital city and a city of international capital. The article uses a long-run approach to explore how, by inventing and nurturing a myth about Edinburgh as a non-industrial city, councillors and planners privileged the ancient and historical character of the city and so conditioned policies associated with urban renewal and land use.
Radiation therapist perspectives on cone-beam computed tomography practices and response to information
Authors: Gillan Caitlin , Li Winnie , Harnett Nicole
Published: May 2013

Introduction

With recent technological advances in image-guided radiation therapy (IGRT), through cone-beam computed tomography (CBCT), more image-related clinical information is being collected, at more frequent intervals throughout the treatment course. As radiation therapy (RT) programmes further develop IGRT technology, the aim of this study is to assess whether the distribution and communication of professional responsibilities is evolving to ensure appropriate use of the technology.

Methods

Radiation therapists practicing at any of the 14 Ontario RT centres were sent an electronic survey (n = 400). Closed-ended quantitative items addressed perceptions regarding policies, comfort, and professional responsibility in addressing CBCT concerns. Focus was on gynaecological, lung, head and neck (H&N) disease sites. Options for qualitative comments and explanations were included where appropriate.

Results

Seventy-nine surveys were submitted. Respondents from 12/14 (85·7%) centres used CBCT for at least one of three disease sites, most commonly on a daily basis. Five of these centres (41·7%) did not require radiation oncologist CBCT review, with others requiring it Day 1 or weekly. Potential CBCT observations of concern were grouped as set-up issues, tumour changes, organ-at-risk (OAR) changes, contour changes and ancillary findings (especially lung and airway changes). Respondents believed they consulted another professional about a CBCT in 20·2% of H&N patients, 19·6% of lung patients and 9·7% of gynaecological patients. The level of comfort in doing so varied from 77·0% for H&N to 89·5% for lung. Respondents were most likely to believe themselves responsible for changes in OARs (92·2% believing themselves responsible), and least likely for ancillary findings (62·7%).

Conclusions

Through preliminary insight from Ontario therapists, a degree of inconsistency is apparent between perceptions, practices and assigned roles in the management of CBCT information. Clear definition of the scope and nature of therapists’ responsibility for interpreting and addressing changes on CBCT images should be developed within each centre.
Maternal diet-induced obesity in swine with leptin resistance modifies puberty and pregnancy outputs of the adult offspring
Authors: Gonzalez-Bulnes A. , Astiz S. , Sanchez-Sanchez R. , Perez-Solana M. , Gomez-Fidalgo E.
Published: May 2013

The assessment of reproductive features (puberty, fertility and prolificacy) in female Iberian pigs indicates that exposition to intrauterine maternal malnutrition, either by deficiency or excess, is associated with juvenile obesity and a significantly earlier age of puberty onset. At adulthood, prenatal exposition to undernutrition affects reproductive outputs by diminishing prolificacy, an effect that was not found in females exposed to prenatal overnutrition.
Eye Movements of Older and Younger Readers When Reading Unspaced Text
Authors: Rayner Keith , Yang Jinmian , Schuett Susanne , Slattery Timothy J.
Published: May 2013

Older and younger readers read normal and unspaced text as their eye movements were monitored. A high or low frequency word was embedded in each sentence. Global analyses yielded large effects of spacing with unspaced text leading to much longer reading times for both groups, but the older readers had much more difficulty with unspaced text than younger readers. Local analyses of the target word revealed large main effects due to age, spacing, and frequency. In general, the older readers had more difficulty with the unspaced text than younger readers and some reasons why they did so are suggested.
Multiple carrier frequency offsets tracking in co‐operative space‐frequency block‐coded orthogonal frequency division multiplexing systems
Authors: Xiong Jun , Huang Qinfei , Xi Yong , Ma Dongtang , Wei Jibo
Published: May 2013

This study addresses the problem of carrier frequency offset (CFO) tracking in co‐operative space‐frequency block‐coded orthogonal frequency division multiplexing (OFDM) systems with multiple CFOs. Considering that the inserted pilot tones are decayed by data subcarriers in the presence of multiple CFOs, a novel recursive residual CFO tracking (R‐RCFOTr) algorithm is proposed. This method first removes CFO‐induced inter‐carrier interference from data subcarriers, and then updates the residual CFO (RCFO) estimation of each OFDM block recursively. When used in conjunction with a multiple CFOs estimator, the proposed R‐RCFOTr can effectively mitigate the impacts from the multiple RCFOs with affordable complexity. Finally, simulation results are provided to validate the effectiveness of our proposed R‐RCFOTr algorithm, which has performance close to that of perfect CFO estimation at moderate and high signal‐to‐noise ratio, and significantly outperforms conventional CFO tracking algorithm for large CFOs.
Single‐symbol decodable space‐time block code for multi‐input–multi‐output systems with four transmit antennas
Authors: Gil Gye‐Tae , Kim Dong‐Hoi
Published: May 2013

This study presents an orthogonal design of space‐time block code (STBC) that is single symbol decodable and enables full diversity and full rate transmission in a quasi‐static channel environment. In the proposed scheme, full diversity is achieved by use of constellation rotation and co‐ordination interpolation as is the case for the co‐ordinate interleaved orthogonal design, whereas the transmission matrix of the proposed code consists of orthogonal columns with all non‐zero elements, alleviating the concern about high peak‐to‐average power ratio. In particular, the proposed code offers lower complexity of channel estimation, and exhibits lower symbol error rate than the conventional quasi‐orthogonal STBC when an maximum‐likelihood decision‐directed channel estimator is assumed. The advantages of the proposed code over the conventional codes are demonstrated through computer simulations. In addition, the selection of the angle of rotation for the proposed design is also presented, regarding the impact of channel estimation error.
Expected complexity analysis of increasing radii algorithm by considering multiple radius schedules
Authors: Ahn Junil , Lee Heung‐No , Kim Kiseon
Published: May 2013

In this study, the authors investigate the expected complexity of increasing radii algorithm (IRA) in an independent and identified distributed Rayleigh fading multiple‐input–multiple‐output channel with additive Gaussian noise and then present its upper bound result. IRA employs several radii to yield significant complexity reduction over sphere decoding, whereas performing a near‐maximum‐likelihood detection. In contrast to the previous expected complexity presented by Gowaikar and Hassibi (2007), where the radius schedule was hypothetically fixed for analytic convenience, a new analytical result is obtained by considering the usage of multiple radius schedules. The authors analysis reflects the effect of the random variation in the radius schedule and thus provides a more reliable complexity estimation. The numerical results support their arguments, and the analytical results show good agreement with the simulation results.
Modelling and performance of three‐phase 6/14 pole flux reversal machine
Authors: More Dagadu Shankar , Fernandes Baylon G.
Published: May 2013

A three‐phase flux reversal machine (FRM) is modelled using the d–q theory. A fictitious ‘electrical gear’ concept is used to simplify modelling and analysis of this machine. The d–q equivalent circuits are proposed based on this gear ratio. A power density of the machine is improved with full pitch winding. The torque obtained with full pitch winding is twice that of concentrated stator pole winding for same input current. FRM with full pitch winding (FPFRM) is compared with the conventional concentrated stator pole winding FRM (CSPFRM). The results obtained using the proposed d–q circuits are compared with those obtained from FEM analysis. A steady‐state performance of FPFRM and CSPFRM is evaluated with proposed d–q circuits. To validate the modelling based on d–q equivalent circuits, a 6/14 pole FRM is fabricated with the conventional concentrated stator pole winding and full pitch winding for wind power application. The analytical results are compared with finite element method (FEM) analysis results and experimental results.
Dilemma zone avoidance development: an on‐board approach
Authors: Chang Tang‐Hsien , Yu Shang‐Min , Wu Yao‐Jan
Published: May 2013

The dilemma zone (DZ) has been discussed in traffic engineering over four decades, because it is positively correlated to potential accidents. The dynamic feature of DZs is indeed difficult resolved and handled only by traffic signal control. This study aims to develop a series of onboard algorithms for DZ avoidance and warning. Three algorithms, DZ estimation, DZ prediction and warning selection are developed. To increase DZ detection accuracy, inputs from roadways, drivers and vehicles are considered. The genetic systematic‐rule is used to optimise the prediction of vehicle motion and the dynamical features of DZs. Experimental results show that the accuracy rates of DZ detection for all scenarios are higher than 90%. Such encouraging results show the reliability and operating practicability of the proposed development.
Real‐time speed profile calculation for fuel saving considering unforeseen situations and travel time
Authors: Jiménez Felipe , López‐Covarrubias Juan Luís , Cabrera Wilmar , Aparicio Francisco
Published: May 2013

Driving style is a key variable which we can influence in order to reduce consumption and pollutant emissions, but other variables also need to be taken into account, such as safety, comfort and travel time. There are different alternatives for obtaining the optimal speed and gear by taking into account the vertical profile of the road and vehicle characteristics. Of these alternatives, Dynamic Programming (DP) provides fairly satisfactory results. However, this calculation involves a high computation cost when it is used to calculate long routes, which poses practical problems when the route can be varied frequently or when unexpected traffic events make it necessary to recalculate the speed profile. This study proposes a solution that is closer to the optimal solution. The algorithm is based on simple action rules for elementary road profiles that have been previously obtained using DP. Furthermore, these rules are recalculated in order to fulfil a predefined travel time. The algorithm has been used in different traffic situations on a real route and differences with the optimal solution have been evaluated so that the conditions where it works better are assessed.
Identification and analysis of motives for eco‐friendly driving within the eco‐move project
Authors: Schießl Caroline , Fricke Nicola , Staubach Maria
Published: May 2013

During the last year eco‐friendly driving and the development of new driver assistance systems that support eco‐friendly driving are increasingly becoming important. One main objective of research in this area is finding ways of motivating drivers to behave ecologically beneficially in a sustainable way and identifying how these motives can be generated, for example, through in‐vehicle assistance or information systems. One aim of the following study was to develop a matrix of the most important eco‐friendly driving motives, moderating and influencing factors (e.g. trip purpose, annual mileage). Another objective was analysis of the influence of different driver characteristics on relevant motives and to deduce first hints for development of applications for generating these motives. The results of the questionnaire study demonstrate that three main motives ‘time’, ‘environment/consumption’ and ‘possibilities to change’ are selectively important and distinctive for various driver groups. The results therefore imply that different strategies and applications or systems might be necessary to change the driver behaviour and to convince them that the ‘eco‐system’ will be beneficial for them. Furthermore, the results describe ideas of what kind of assistance or information systems the drivers would prefer as a support system. This information can help in the design of future eco‐driving support systems.
Robust detection system of illegal lane changes based on tracking of feature points
Authors: Lee Heesin , Jeong Sunghwan , Lee Joonwhoan
Published: May 2013

This study proposes a robust real‐time system to detect vehicles that change lanes illegally based on tracking feature points. The algorithm in the system does not need to switch depending on the illumination conditions, such as day and night. The camera is assumed to be heading in the opposite direction to the traffic flow. Before starting, the system manager should initially designate several regions that are utilised for detection. Then, the proposed algorithm consists of three stages, such as extracting feature points of corners, tracking the feature points attached to vehicles and detecting a vehicle that violates legal lane changes. For the feature extraction stage, the authors used a robust and fast algorithm that can provide stable corners without distinguishing between day and night or weather conditions. Salient points are selected among the corner points for registration and tracking. Normalised cross‐correlation is used to track the registered feature points. Finally, illegal change‐of‐lane is determined by the information obtained from the tracked corners without grouping them for segmentation. The proposed system showed excellent performance in terms of the accuracy and the computation speed.
Radiation‐efficient 60 GHz on‐chip dipole antenna realised by reactive impedance metasurface
Authors: Saadat Soheil , Mosallaei Hossein , Afshari Ehsan
Published: May 2013

In this study, a unique method for designing low‐cost, energy‐efficient integrated antenna operating in 57–64 GHz band is proposed. The design utilises an artificial surface called reactive impedance surface (RIS) to enhance the antenna radiation efficiency. RIS substrate demonstrates unique potential in terms of minimising the size, reduced coupling between the antenna and silicon substrate and hence, lowering the wave penetration through the lossy substrate and finally achieving wider bandwidth and higher efficiency. This artificial surface is composed of two‐dimensional periodic square patches printed on a thin metal‐backed dielectric substrate which offers an imaginary impedance performance. Design characterisation, simulation, fabrication and measurement are provided and the results show an enhanced directivity with suppressed back radiation compared with similar works.
Time‐domain techniques in microwave circuit simulation
Authors: Brazil Thomas J.
Published: May 2013

Microwave circuit simulation has always posed particular difficulties especially in highly non‐linear applications because of the presence of distributed or electromagnetic structures, which are usually passive and linear, but difficult to incorporate effectively in time‐domain analysis. A variety of specialised techniques has evolved to cope with this situation with reasonable success. In recent years, microwave systems are becoming more integrated and complex and often involve ‘mixed‐signals’ that may operate over a very wide range of time scales, creating new simulation challenges. This study reviews the issues involved and suggests a practical paradigm for generalised time‐domain simulation of microwave circuits.
Design method for matching circuits of general multiplexers
Authors: Taravati Sajjad , Khalaj‐Amirhosseini Mohammad
Published: May 2013

A general design method for matching circuits for multiplexers with arbitrary channel bandwidths and interchannel spacing, based on microstrip non‐uniform transmission lines is presented. For verification, an universal mobile telecommunications systems/worldwide interoperability for microwave access triplexer with different channel specifications has been designed and fabricated. The proposed triplexer uses one microstrip matching network and three combined hairpin‐line filters. The matching network was designed in three different ways and in the third one, three flat passbands and high channels isolation in the frequency band, 1.92–2.69 GHz have been achieved. Measured results are in good agreement with simulated results that verify the accuracy of the design procedure. The comparison of the results of the proposed triplexer with those of the other triplexers clarifies the benefits of the proposed design method.
Analysis of arbitrary multiple‐loop antennas around a conducting cone, with rotational symmetry
Authors: Ghosh Bratin , Haque SK. Moinul , Halder Prasanta
Published: May 2013

A rigorous technique is presented for the analysis of multiple loops around a conducting cone, taking into account mutual coupling. A single and a two/five‐loop system around the cone is investigated using the technique to characterise the effect of coupling of parasitic loops on the primary‐loop antenna. A two‐loop system over the cone‐tip is also analysed. It is found that the parasitic loop in this case can significantly improve the matching characteristics of the primary loop. The technique is also used to analyse a three‐loop director–reflector configuration for loops below and above the cone‐tip. The radiation characteristics were also evaluated. The computed results were verified using simulation and measurements.
Development of a directional dual‐band planar antenna for wireless applications
Authors: Quan Xulin , Li RongLin , Jin Guiping , Tentzeris Manos M.
Published: May 2013

A new type of directional dual‐band antenna is developed for 2.4/5 GHz wireless applications. The dual‐band antenna consists of a longer dipole for the lower band and a pair of shorter dipoles for the upper band. A simple coupling microstrip line is employed to excite the dipoles. Both the dual‐band antenna and the feeding microstrip line are printed on the same substrate, leading to a fully planar structure. The dual‐band planar antenna achieves a desirable directional radiation pattern with an antenna gain of near 8 dBi for the lower band and 9–10 dBi for the upper band. A comprehensive analysis and design for the development of the directional dual‐band antenna is presented.
Co‐operating retrodirective system
Authors: Chan Pak , Fusco Vincent
Published: May 2013

Practical demonstration of the operational advantages gained through the use of a co‐operating retrodirective array (RDA) basestation and Van Atta node arrangements is discussed. The system exploits a number of inherent RDA features to provide analogue real time multifunctional operation at low physical complexity. An active dual‐conversion four element RDA is used as the power distribution source (basestation) while simultaneously achieving a receive sensitivity level of −109 dBm and 3 dB automatic beam steering angle of ±45°. When mobile units are each equipped with a semi‐passive four element Van Atta array, it is shown mobile device orientation issues are mitigated and optimal energy transfer can occur because of automatic beam formation resulting from retrodirective self‐pointing action. We show that operation in multipath rich environments with or without line of sight acts to reduce average power density limits in the operating volume with high energy density occurring at mobile nodes sites only. The system described can be used as a full duplex ASK communications link, or, as a means for remote node charging by wireless means, thereby enhancing deployment opportunities between un‐stabilised moving platforms.
High‐gain low‐noise Ku‐band mixer with inverting transconductance technique
Authors: Lee Ji‐Young , Kang Yun‐Mo , Lee Sang‐Kon , Yun Tae‐Yeoul
Published: May 2013

In this study, the authors present a high‐gain, low‐noise Ku‐band down conversion mixer in 0.18 μm complimentary metal oxide semiconductor technology. An inverting transconductance technique is adopted to obtain a high conversion gain, which uses both inverting and current bleeding effects. The noise performance is improved by using a switched biasing technique. Current bleeding and inductor bridging techniques allow the simultaneous achievement of low noise and high conversion gain. The proposed mixer offers a measured conversion gain from 10.1 to 13.6 dB and a noise figure from 8.6 to 11.2 dB over 11 to 20 GHz and a third order input intercept point of −5 dBm at 16 GHz while consuming 8.3 mW from a 1.8 V supply voltage. The chip size, including test pads, is 0.77 × 0.75 mm2.
Energy‐efficient network design via modelling: optimal designing point for energy, reliability, coverage and end‐to‐end delay
Authors: Ansari Mohammad Saeed , Mahani Ali , Kavian Yousef S.
Published: May 2013

Considering that practical wireless sensor networks are mostly built upon energy‐constrained sensor nodes, network lifetime becomes a key deployment factor for sustainability of such networks initiating an attempt for prolonging the lifetime. Adopting a new multi‐mode switching protocol for sensor nodes between active and sleep states, in this study, the authors propose a new mathematical method using an embedded simulation‐based computing of an energy‐efficient strategy performance metric to maintain resiliency of the network against side effects appearing in duty‐cycling protocols. Here, the authors use a Monte Carlo simulation to estimate network reliability. Then the proposed mathematical model enables us to build a decision for optimised performance upon trade‐offs between consumed energy, reliability, coverage intensity and end‐to‐end delays by locating a network's operational points. The authors show the trade‐off operational significance of the model against the percentage of sleeping probability via some design factors including figure of merit.
Soft single switch resonant buck converter with inherent PFC feature
Authors: Emrani Amin , Amini Mohammad Reza , Farzaneh‐Fard Hosein
Published: May 2013

In this study a new fully soft switched converter with a single switch is presented. The relatively small value of required passive circuit elements in this converter makes its implementation simple and cost‐efficient. Since this converter operates at fully soft‐switching conditions without any extra switches and low number of circuit components, the proposed converter is highly efficient. The other advantage of this converter is its inherent power factor correction (PFC) feature. In this study, the proposed converter is introduced and its theoretical analysis is presented. Also a prototype converter is implemented and the experimental results are presented to verify the theoretical analysis.
Experimental evaluation of four‐phase floating interleaved boost converter design and control for fuel cell applications
Authors: Kabalo Mohammad , Paire Damien , Blunier Benjamin , Bouquain David , Godoy Simões Marcelo , Miraoui Abdellatif
Published: May 2013

Power electronic converters are essential part of hybrid fuel cell automotive application systems. The converter needs to provide high‐voltage ratio for a wide range of input voltage. In addition, the converter should have high efficiency for a wide range of duty cycle control range. A four‐phase floating interleaved boost converter (FIBC) is analysed and a small‐signal AC model using an averaged pulse‐width modulation (PWM) switch technique is used for supporting the feedback controller and aiding a frequency response design. The small‐signal AC model as well as the current controller are validated by simulation and evaluated by experimental results. The proposed converter has competitive device ratings, the total inductance volume and weight is decreased, current ripple is minimised and converter efficiency and reliability are improved. Proof of concept of the proposed topology is demonstrated through an experimental prototype.
Distributed control system for a parallel‐connected AC/DC converters
Authors: Chunkag Viboon , Kanthaphayao Yutthana , Kamnarn Uthen
Published: May 2013

This study presents a distributed control system for parallel‐connected AC/DC converters. The proposed system composed of isolated CUK AC/DC converters which each converter has its own controller and a simple current‐sharing circuit. The purposes are modular system and distributed control. The control system consists of an analogue circuit and a microcontroller. The analogue circuit is used for a current sharing and control the input current to be in‐phase with the input voltage. The microcontroller is used for generating the control signals to adjust gain of the current sharing and to control the output voltage. The performance evaluation was conducted through the simulation and experimental results, on a three‐module parallel‐connected, with a 540 W load, a − 48 V of DC bus output voltage. The performance of the proposed system has been achieved as follows: the current sharing is quite well; the redundant operation can be implemented in this system, the fast transient response and a high‐power factor.
Analytical calculation of resonant inductance for zero voltage switching in phase‐shifted full‐bridge converters
Authors: Hallworth Michael , Ben Potter A. , Shirsavar Seyed Ali
Published: May 2013

The phase‐shift full‐bridge (PSFB) converter allows high‐efficiency power conversion at high frequencies through zero voltage switching (ZVS); the parasitic drain‐to‐source capacitance of the metal‐oxide semiconductor field‐effect transistor is discharged by a resonant inductance before the switch is gated resulting in near zero turn‐on switching losses. Typically, an extra inductance is added to the leakage inductance of a transformer to form the resonant inductance necessary to charge and discharge the parasitic capacitances of the PSFB converter. However, many PSFB models do not consider the effects of the magnetising inductance or dead‐time in selecting the resonant inductance required to achieve ZVS. The choice of resonant inductance is crucial to the ZVS operation of the PSFB converter. Incorrectly sized resonant inductance will not achieve ZVS or will limit the load regulation ability of the converter. This study presents a unique and accurate equation for calculating the resonant inductance required to achieve ZVS over a wide load range incorporating the effects of the magnetising inductance and dead‐time. The derived equations are validated against PSPICE simulations of a PSFB converter and extensive hardware experimentations.
Improved zero‐voltage‐switching pulse width modulation full bridge converter with self‐regulating auxiliary current
Authors: Chen Zhong , Liu Shasha , Shi Liangchen
Published: May 2013

An improved zero‐voltage‐switching (ZVS) phase‐shift full‐bridge converter with self‐regulating auxiliary current is proposed. ZVS of lagging‐leg switches can be achieved in whole conversion range because of the introduced active auxiliary circuit. Meanwhile, the auxiliary circuit that features simple control of the auxiliary switches has no effect on the main power transferring path and the auxiliary energy stored for ZVS of lagging‐leg can be regulated by the load current without significantly increasing conduction loss over the entire load range. The operation principle of the proposed converter is discussed in detail and further simplification of the proposed topology is suggested. The design method of key parameters is carefully depicted. Finally, the operation and performance of the proposed converter are verified on a 1 kW/54 V, 100 kHz prototype.
Proposal for optimising the provision of inertial response reserve of variable‐speed wind generators
Authors: Díaz Guzmán , Casielles Pedro G. , Viescas Ceferino
Published: May 2013

Wind generators provide efficient harvesting of wind energy at the cost of worsening the inertial response during load‐frequency events. The inertial response may be improved, however, by emulating the response of synchronous generators by means of additional control loops that sense frequency deviations. Energy reserve is needed in such a case if overloading, stalling or power request for speed recovery are to be avoided. In this study, the authors formulate an optimal problem to achieve the aim of conciliating the opposite objectives of minimum loss of power production and required minimum inertial reserve. The solution to the problem gives the pitch angles and the associated, modified speed against power tracking characteristics needed to support high kinetic energy storage with minimum loss of power production. The analyses confirm that a proper reserve can be maintained, mainly at low wind speeds, with a reduced amount of de‐loading.
Photovoltaic metering configurations, feed‐in tariffs and the variable effective electricity prices that result
Authors: McKenna Eoghan , Thomson Murray
Published: May 2013

Occupants of dwellings with photovoltaic (PV) systems can often benefit financially by time‐shifting their use of electricity in relation to the times when the PV is generating. This financial benefit is owing to differences between the import and export prices, which in some cases can be a factor of four or more. Quantifying the exact financial benefit in terms of the dwelling's effective electricity prices is, however, not trivial; it depends on the physical meter arrangement, the dwelling's electricity tariffs (including any feed‐in‐tariff), the instantaneous levels of PV generation and household demand. This study reviews typical metering and tariff configurations for the UK, and Germany, and systematically considers how the effective price may be calculated. This study reviews and expands upon general advice for occupants aiming to reduce electricity bills: demand should be kept below generation; external irradiance is a useful proxy for determining effective electricity prices. Furthermore, designers of feed‐in tariffs should consider that focusing on generation payments encourages consumption typically around mid‐day, which may be counterproductive from a grid‐balancing and environmental perspective. Conversely, a focus on export payments discourages mid‐day consumption but may increase the risk of over‐voltages in local networks.
Morphology and size control of nanocalcium carbonate crystallised in reverse micelle system with cationic surfactant cetyltrimethylammonium bromide
Authors: Wang Nong , Wang Xingquan , Yang Lijuan , Chen Huisheng
Published: May 2013

The influence of ω0, the mole ratio of water‐to‐surfactant content ([H2O]/[surfactant]), on the crystal size of calcium carbonate (CaCO3) produced by reaction crystallisation in microemulsion systems was investigated. Crystallisation was induced by the reaction between an aqueous solution of sodium carbonate and water in oil micellar solutions of calcium chloride stabilised by cationic surfactant cetyltrimethylammonium bromide and cosurfactant n‐ butylalcohol. The X‐ray diffraction results showed that calcite is the main state of CaCO3 crystal when ω0> 30, but because of the stable reverse micelles system, vaterite was the predominant crystal form when ω0< 30. Scanning electron microscopy and high‐resolution transmission electron microscopy results showed spherical CaCO3 nanoparticles obtained with narrow size distribution, and with the ratio of water‐to‐surfactant increasing from 3.40 to 22.63, the particles size increased from 15 to 70 nm. The influence of ω0 on the crystal size and morphology of CaCO3 was very clear.
Excess volume in nanocrystalline lithium‐carbon system
Authors: Xu Wenwu , Song Xiaoyan , Seyring Martin , He Jiangtao , Drüe Martin , Rettenmayr Markus
Published: May 2013

A method that combines model calculations with X‐ray diffraction analyses on prepared nanocrystalline samples has been developed to determine the excess volume and its dependence on grain size in nanocrystalline anode materials. In the model calculations, the geometry of grains in nanocrystalline systems is treated as a spherical shape for simplicity. It has been determined that the excess volume depends on grain size and atomic density at grain boundaries. The nanocrystalline Li2C2 alloy was taken as an example of the nanostructured anodes and its grain boundary expansion was generated by the excess volume at different grain size levels.
Liquid-crystal mediated nanoparticle interactions and gel formation
Authors: Whitmer Jonathan K. , Joshi Abhijeet A. , Roberts Tyler F. , de Pablo Juan J.
Published: May 2013

Colloidal particles embedded within nematic liquid crystals exhibit strong anisotropic interactions arising from preferential orientation of nematogens near the particle surface. Such interactions are conducive to forming branched, gel-like aggregates. Anchoring effects also induce interactions between colloids dispersed in the isotropic liquid phase, through the interactions of the pre-nematic wetting layers. Here we utilize computer simulation using coarse-grained mesogens to perform a molecular-level calculation of the potential of mean force between two embedded nanoparticles as a function of anchoring for a set of solvent conditions straddling the isotropic–nematic transition. We observe that strong, nontrivial interactions can be induced between particles dispersed in mesogenic solvent, and explore how such interactions might be utilized to induce a gel state in the isotropic and nematic phases.
Coarse-grain simulations of active molecular machines in lipid bilayers
Authors: Huang Mu-Jie , Kapral Raymond , Mikhailov Alexander S. , Chen Hsuan-Yi
Published: May 2013

A coarse-grain method for simulations of the dynamics of active protein inclusions in lipid bilayers is described. It combines the previously proposed hybrid simulations of bilayers [M.-J. Huang, R. Kapral, A. S. Mikhailov, and H.-Y. Chen, J. Chem. Phys. 137, 055101 (2012)]10.1063/1.4736414, based on molecular dynamics for the lipids and multi-particle collision dynamics for the solvent, with an elastic-network description of active proteins. The method is implemented for a model molecular machine which performs active conformational motions induced by ligand binding and its release after reaction. The situation characteristic for peripheral membrane proteins is considered. Statistical investigations of the effects of single active or passive inclusions on the shape of the membrane are carried out. The results show that the peripheral machine produces asymmetric perturbations of the thickness of two leaflets of the membrane. It also produces a local saddle in the midplane height of the bilayer. Analysis of the power spectrum of the fluctuations of the membrane midplane shows that the conformational motion of the machine perturbs these membrane fluctuations. The hydrodynamic lipid flows induced by cyclic conformational changes in the machine are analyzed. It is shown that such flows are long-ranged and should provide an additional important mechanism for interactions between active inclusions in biological membranes.
Data processing and analysis of the imaging Thomson scattering diagnostic system on HT-7 tokamak
Authors: Han Xiaofeng , Shao Chunqiang , Xi Xiaoqi , Zhao Junyu , Qing Zang , Yang Jianhua , Dai Xingxing , Shinichiro Kado
Published: May 2013

A high spatial resolution imaging Thomson scattering diagnostic system was developed in ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences). After about one month trial running on the superconducting HT-7 (Hefei Tokamak-7) tokamak, the system was proved to be capable of measuring plasma electron temperature. The system setup and data calibration are described in this paper and then the instrument function is studied in detail, as well as the measurement capability, an electron temperature of 50 eV to 2 keV and density beyond 1 × 1019 m−3. Finally, the data processing method and experimental results are presented.