bluuebunny/crossref_metadata_2025 huggingface dataset:
Current blockage experiments: force time histories on obstacle arrays in combined steady and oscillatory motion
Authors: Santo H. , Taylor P. H. , Williamson C. H. K. , Choo Y. S.
Published: December 2013

This paper revisits the problem of forces on obstacle arrays in combined waves and an in-line steady current. The intended application is the design and reassessment of offshore platforms. A series of experiments are performed on planar grids moved in both steady and oscillatory motion through otherwise stationary water. Detailed comparisons are made to a wave-current–structure interaction model recently presented by Taylor, Santo & Choo (Ocean Engng, vol. 57, 2013, pp. 11–24). We present new features of the model and test these against the experimental data. For relatively small current speed (${u}_{c} $) compared with oscillatory velocity amplitude (${u}_{w} $) with phase angle ($\omega t$), the drag force time history on grids with solid area ($A$) and projected frontal area (${A}_{f} $) is well approximated by a summation of the wave drag and the current drag components independently, so there is no ${u}_{w} \times {u}_{c} $ cross-term. The wave drag component is proportional to $\cos \omega t\vert \cos \omega t\vert $, while the current drag component to $\vert \cos \omega t\vert $, i.e. it is phase-locked to the oscillatory wave crests. The form of the predicted time history is new, so much of this paper is occupied in testing the adequacy of this theoretical form both in terms of an improved Morison-type formulation and also in the precise variation of the experimental drag force in time. We show that the measured crest and trough peak values of the drag force are consistent with the force peaks and troughs of the model prediction. The odd frequency harmonics of the measured drag force scale as the square of the oscillatory velocity amplitude $({ u}_{w}^{2} )$ and on the total hydrodynamic area (${C}_{d} A$). The shape of the odd harmonics is very similar to that for a pure oscillatory motion without steady current, but there are also even frequency harmonics associated with the current component. The even harmonics of the force scale as the square of the current speed $({ u}_{c}^{2} )$ and on the ${A}_{f} $, not on the ${C}_{d} A$. All of the above features are identified within the experimental data, and provide considerable support for the new current blockage model.

The new model is also shown to fit the entire force time history well for a wide range of individual cases, with different blockage ratio ($A/ {A}_{f} $) and number of grids, requiring only calibration of the Morison-type drag and inertia coefficients. In contrast, the industry-standard form of the Morison equation can only be matched at a single instant of the oscillation cycle, so present practice should be regarded as seriously inadequate for combined steady current and oscillatory flow acting on obstacle arrays.
Evaluation of periotic–timpanic bone complex ofSotalia guianensis(Cetacea: Delphinidae) as tool in identification of geographic variations
Authors: Arcoverde Danilo Leal , Emin-Lima Renata , Costa Alexandra Fernandes , Di Beneditto Ana Paula Madeira , Siciliano Salvatore , Sena Leonardo , Moreno Ignacio Benites , De Sousa E Silva José
Published: December 2013

Morphometric characteristics of the periotic–timpanic bone complex in the middle ear of cetaceans, are effective characteristics in evaluating systematics. However, they have not been used for studies of geographic variation regarding dolphins of the genusSotalia. This study aimed to compare the periotic–timpanic ofSotalia guianensisfrom four distinct locations, considered here as different operational taxonomic units, Amapá/Pará (AM/PA), Maranhão/Piauí (MA/PI), Ceará (CE), and Rio de Janeiro (RJ), using 21 morphometric measurements. Multivariate analysis showed significant distinction mainly between the units of northern (AM/PA and MA/PI) and south-eastern (RJ) Brazilian coast. The timpanic bone showed variation, reaching larger sizes in the Brazilian south coast unit, corroborating current molecular data on the geographic variation ofS. guianensis.
Bullying in elementary school and psychotic experiences at 18 years: a longitudinal, population-based cohort study
Authors: Wolke D. , Lereya S. T. , Fisher H. L. , Lewis G. , Zammit S.
Published: December 2013

Background

Victims of bullying are at risk for psychotic experiences in early adolescence. It is unclear if this elevated risk extends into late adolescence. The aim of this study was to test whether bullying perpetration and victimization in elementary school predict psychotic experiences in late adolescence.

Method

The current study is based on the Avon Longitudinal Study of Parents and Children (ALSPAC), a prospective community-based study. A total of 4720 subjects with bullying perpetration and victimization were repeatedly assessed between the ages of 8 and 11 years by child and mother reports. Suspected or definite psychotic experiences were assessed with the Psychosis-Like Symptoms semi-structured interview at age 18 years.

Results

Controlling for child's gender, intelligence quotient at age 8 years, childhood behavioural and emotional problems, and also depression symptoms and psychotic experiences in early adolescence, victims [child report at 10 years: odds ratio (OR) 2.4, 95% confidence interval (CI) 1.6–3.4; mother report: OR 1.6, 95% CI 1.1–2.3], bully/victims (child report at 10 years: OR 3.1, 95% CI 1.7–5.8; mother: OR 2.9, 95% CI 1.7–5.0) and bullies (child report at 10 years: OR 4.9, 95% CI 1.3–17.7; mother: OR 1.2, 95% CI 0.46–3.1, n.s.) had a higher prevalence of psychotic experiences at age 18 years. Path analysis revealed that the association between peer victimization in childhood and psychotic experiences at age 18 years was only partially mediated by psychotic or depression symptoms in early adolescence.

Conclusions

Involvement in bullying, whether as victim, bully/victim or bully, may increase the risk of developing psychotic experiences in adolescence. Health professionals should ask routinely during consultations with children about their bullying of and by peers.
The promise of developmental psychopathology: Past and present
Authors: Sroufe L. Alan
Published: December 2013

Progress in the field of developmental psychopathology is appraised in general and with regard to the particular lens of our understanding of the development of disorder. In general, the outpouring of research on various features of disorder and underlying processes could not have even been imagined 25 years ago. The progress is dazzling. At the same time, work on the development of disorders, beginning with antecedent patterns of adaptation, pales in comparison with work on the correlates of disorder. However, progress has been made. It is well established that the brain develops in the context of experience and that organism and environment continually interact over time. Something is now known about pathways leading to certain disorders and what initiates and impels individuals along them. If developmental psychopathology is to completely fulfill its promise of offering new ways of conceptualizing disorder and new guidance for prevention and intervention, much more work on developmental processes and a new way of exploring the development of disorder will be needed. Such a path is suggested.
Epigenetic mechanisms in the development of behavior: Advances, challenges, and future promises of a new field
Authors: Roth Tania L.
Published: December 2013

In the past decade, there have been exciting advances in the field of behavioral epigenetics that have provided new insights into a biological basis of neural and behavioral effects of gene–environment interactions. It is now understood that changes in the activity of genes established through epigenetic alterations occur as a consequence of exposure to environmental adversity, social stress, and traumatic experiences. DNA methylation in particular has thus emerged as a leading candidate biological pathway linking gene–environment interactions to long-term and even multigenerational trajectories in behavioral development, including the vulnerability and resilience to psychopathology. This paper discusses what we have learned from research using animal models and from studies in which the translation of these findings has been made to humans. Studies concerning the significance of DNA methylation alterations in outcomes associated with stress exposure later in life and dysfunction in the form of neuropsychiatric disorders are highlighted, and several avenues of future research are suggested that promise to advance our understanding of epigenetics both as a mechanism by which the environment can contribute to the development of psychiatric disorders and as an avenue for more effective intervention and treatment strategies.
Stress physiology and developmental psychopathology: Past, present, and future
Authors: Doom Jenalee R. , Gunnar Megan R.
Published: December 2013

Research on the hypothalamic–pituitary–adrenocortical (HPA) axis has emerged as a vital area within the field of developmental psychopathology in the past 25 years. Extensive animal research has provided knowledge of the substrates and physiological mechanisms that guide development of stress reactivity and regulation using methods that are not feasible in humans. Recent advances in understanding the anatomy and physiology of the HPA axis in humans and its interactions with other stress-mediating systems, including accurate assessment of salivary cortisol, more sophisticated neuroimaging methods, and a variety of genetic analyses, have led to greater knowledge of how psychological and biological processes impact functioning. A growing body of research on HPA axis regulation and reactivity in relation to psychopathology has drawn increased focus on the prenatal period, infancy, and the pubertal transition as potentially sensitive periods of stress system development in children. Theories such as the allostatic load model have guided research by integrating multiple physiological systems and mechanisms by which stress can affect mental and physical health. However, almost none of the prominent theoretical models in stress physiology are truly developmental, and future work must incorporate how systems interact with the environment across the life span in normal and atypical development. Our theoretical advancement will depend on our ability to integrate biological and psychological models. Researchers are increasingly realizing the importance of communication across disciplinary boundaries in order to understand how experiences influence neurobehavioral development. It is important that knowledge gained over the past 25 years has been translated to prevention and treatment interventions, and we look forward to the dissemination of interventions that promote recovery from adversity.
Opportunities and challenges to the development of healthy children and youth living in diverse communities
Authors: Spencer Margaret Beale , Swanson Dena Phillips
Published: December 2013

The field of developmental psychopathology has seen growth in research focusing on interdisciplinarity and normative developmental processes, including context-linked coping and adaptations. However, there continues to be an uncomfortable and unarticulated perspective to view others as having culture and “the self” as representing the standard. A call for explicit cultural considerations in research is needed to augment the impact of these new and other significant conceptual contributions noted. Sociopolitical influences on social contexts relevant to the different trajectories associated with youths' opportunities and challenges are presented. We focus on macrolevel factors that frame contexts in which individual development occurs. A federal and educational policy is used to illustrate how unexamined cultural traditions and patterns embedded in research and policy impact development. These examples provide insight in presenting issues of vulnerability, particularly for youth, and afford opportunities to present advances and challenges paralleled in the developmental psychopathology field.
Delayed extracorporeal membrane oxygenation in children after cardiac surgery: two-institution experience
Authors: Gupta Punkaj , DasGupta Rahul , Best Derek , Chu Craig B. , Elsalloukh Hassan , Gossett Jeffrey M. , Imamura Michiaki , Butt Warwick
Published: December 2013

Objective:There are limited data on the outcomes of children receiving delayed (≥7 days) extracorporeal membrane oxygenation after cardiac surgery. The primary aim of this project is to identify the aetiology and outcomes of extracorporeal membrane oxygenation in children receiving delayed (≥7 days) extracorporeal membrane oxygenation after cardiac surgery.Patients and methods:We conducted a retrospective review of all children ≤18 years supported with delayed extracorporeal membrane oxygenation after cardiac surgery between the period January, 2001 and March, 2012 at the Arkansas Children’s Hospital, United States of America, and Royal Children’s Hospital, Australia. The data collected in our study included patient demographic information, diagnoses, extracorporeal membrane oxygenation indication, extracorporeal membrane oxygenation support details, medical and surgical history, laboratory, microbiological, and radiographic data, information on organ dysfunction, complications, and patient outcomes. The outcome variables evaluated in this report included: survival to hospital discharge and current survival with emphasis on neurological, renal, pulmonary, and other end-organ function.Results:During the study period, 423 patients undergoing cardiac surgery were supported with extracorporeal membrane oxygenation at two institutions, with a survival of 232 patients (55%). Of these, 371 patients received extracorporeal membrane oxygenation <7 days after cardiac surgery, with a survival of 205 (55%) patients, and 52 patients received extracorporeal membrane oxygenation ≥7 days after cardiac surgery, with a survival of 27 (52%) patients. The median duration of extracorporeal membrane oxygenation run for the study cohort was 5 days (interquartile range: 3, 10). In all, 14 patients (25%) received extracorporeal membrane oxygenation during active cardiopulmonary resuscitation with chest compressions. There were 24 patients (44%) who received dialysis while being on extracorporeal membrane oxygenation. There were eight patients (15%) who had positive blood cultures and four patients (7%) who had positive urine cultures while being on extracorporeal membrane oxygenation. There were nine patients (16%) who had bleeding complications associated with extracorporeal membrane oxygenation runs. There were 10 patients (18%) who had cerebrovascular thromboembolic events associated with extracorporeal membrane oxygenation runs. Of these, 19 patients are still alive with significant comorbidities.Conclusions:This study demonstrates that mortality outcomes are comparable among children receiving extracorporeal membrane oxygenation ≥7 days and <7 days after cardiac surgery. The proportion of patients receiving extracorporeal membrane oxygenation ≥7 days is small and the aetiology diverse.
REAL BUSINESS CYCLES AFTER THREE DECADES
Authors: Altug Sumru , Young Warren
Published: December 2013

The transcript of a panel discussion marking three decades of the real business cycle approach to macroeconomic analysis as manifested in Kydland and Prescott's “Time to Build” (Econometrica, 1982) and Long and Plosser's “Real Business Cycles” (Journal of Political Economy, 1983). The panel consists of Edward Prescott, Finn Kydland, Charles Plosser, John Long, Thomas Cooley, and Gary Hansen. The discussion is moderated by Sumru Altug and Warren Young. The panel touches on a wide variety of issues related to real business cycle models, including their history and methodology, starting with the work of Prescott and Kydland at Carnegie Tech and Plosser and Long at Rochester; their applications to policy; and their role in the recent financial crisis and likely future.

The panel discussion was held in a session sponsored by the History of Economics Society at the Allied Social Sciences Association (ASSA) meetings in the Randle A Room of the Manchester Grand Hyatt Hotel in San Diego, California.
A “Thickness Series”: Weak Signal Extraction of ELNES in EELS Spectra From Surfaces
Authors: Zhu Guo-zhen , Botton Gianluigi A.
Published: December 2013

We report a new simple but effective method to extract the weak surface signals from a “thickness series” of recorded electron energy-loss spectra. Using precise thickness measurements and energy-loss near-edge structures measured at increasing thicknesses, we are able to extract the surface and bulk components in the series. The electronic structure and bonding information from SrTiO3 (001) reconstructed surfaces have been successfully obtained by applying this approach. This approach can be applied to study many other cases including absorbed monolayers and beam-sensitive interfaces.
DOES A GREEN LEAF CONFIRM THAT ALL RAVENS ARE BLACK? BRIEF REFLECTIONS ON A PARADOX OF CONFIRMATION
Authors: Miles Tim
Published: December 2013

The paradox is that a natural idea of what counts as confirmation implies that a green leaf confirms the hypothesis that all ravens are black. The following brief paper explains this paradox, proposes a resolution in terms of relative frequency, and suggests that this shows a link between confirmation and falsification.
The Type D Construct
Authors: Grande Gesine , Romppel Matthias , Michal Matthias , Brähler Elmar
Published: December 2013

The interaction of negative affectivity (NA) and social inhibition (SI), known as the Type D personality, is associated with a worse prognosis in cardiac patients. Until now, causal models have been speculative, and this is partly due to a lack of clarity related to the validity of SI, its role in emotion regulation, and the postulated independence of social and emotional functioning. To examine the construct validity of the Type D personality, we analyzed associations of NA and SI with different measures of affectivity, social anxiety, and social competencies in a German population-based representative sample (n = 2,495). Both NA and SI were associated with all other measures of social functioning and negative affect (all rs > .30) and showed considerable cross-loadings (NA: a 1 = .39, a 2 = .63; SI: a1 = .73 and a2 = .34) in a two-factor solution with the factors labeled as Social Functioning and Negative Affectivity. The SI subscale did not properly differentiate between social fears and social competencies, which emerged as rather different aspects of social functioning. Further studies should examine the effect of broader dimensions of social orientation and competencies and their interaction with NA on cardiac prognosis.
Rorschach Texture Responses Are Related to Adult Attachment via Tactile Imagery and Emotion
Authors: Iwasa Kazunori , Ogawa Toshiki
Published: December 2013

This study examined an underlying mechanism of the relationships among Rorschach texture responses and adult attachment dimensions (attachment anxiety and attachment avoidance), focusing on the vividness of tactile imagery and emotion as mediators. In Study 1, Japanese undergraduate students (n = 20) completed the Rorschach and the Vividness of Tactile Imagery Scale. A poisson regression analysis revealed that greater vividness of tactile imagery was associated with an increased number of texture responses. In Study 2, Japanese undergraduate students (n = 224) completed the Experiences in Close Relationship Scale for the Generalized Other and the Vividness of Tactile Imagery Scale. A path analysis revealed that attachment avoidance weakened the strength of emotional responses accompanying the generation of tactile imagery, and greater emotional responses enhanced the vividness of tactile imagery. These results suggest the possibility that attachment avoidance indirectly reduces texture responses on the Rorschach.
The Rho GTPase Rac1 is required for recycling endosome‐mediated secretion of TNF in macrophages
Authors: Stanley Amanda C , Wong Colin X , Micaroni Massimo , Venturato Juliana , Khromykh Tatiana , Stow Jennifer L , Lacy Paige
Published: December 2013

Rho GTPases are required for many cellular events such as adhesion, motility, and membrane trafficking. Here we show that in macrophages, the Rho GTPases Rac1 and Cdc42 are involved in lamellipodia and filopodia formation, respectively, and that both of these Rho GTPases are essential for the efficient surface delivery of tumor necrosis factor (TNF) to the plasma membrane following TLR4 stimulation. We have previously demonstrated intracellular trafficking of TNF via recycling endosomes in lipopolysaccharide (LPS)‐activated macrophages. Here, we further define a specific role for Rac1 in intracellular TNF trafficking, demonstrating impairment in TNF release following TLR4 stimulation in the presence of a Rac inhibitor, in cells expressing a dominant negative (DN) form of Rac1, and following small interfering RNA (siRNA) knockdown of Rac1. Rac1 activity was required for TNF trafficking but not for TLR4 signaling following LPS stimulation. Reduced TNF secretion was due to a defect in Rac1 activity, but not of the closely related Rho GTPase Rac2, demonstrated by the additional use of macrophages derived from Rac2‐deficient mice. Labeling recycling endosomes by the uptake of fluorescent transferrin enabled us to show that Rac1 was required for the final stages of TNF trafficking and delivery from recycling endosomes to the plasma membrane. Thus, actin remodeling by the Rho GTPase Rac1 is required for TNF cell surface delivery and release from macrophages.
Distinguishing between yield advances and yield plateaus in historical crop production trends
Authors: Grassini Patricio , Eskridge Kent M. , Cassman Kenneth G.
Published: December 2013

Food security and land required for food production largely depend on rate of yield gain of major cereal crops. Previous projections of food security are often more optimistic than what historical yield trends would support. Many econometric projections of future food production assume compound rates of yield gain, which are not consistent with historical yield trends. Here we provide a framework to characterize past yield trends and show that linear trajectories adequately describe past yield trends, which means the relative rate of gain decreases over time. Furthermore, there is evidence of yield plateaus or abrupt decreases in rate of yield gain, including rice in eastern Asia and wheat in northwest Europe, which account for 31% of total global rice, wheat and maize production. Estimating future food production capacity would benefit from an analysis of past crop yield trends based on a robust statistical analysis framework that evaluates historical yield trajectories and plateaus.
An optimized method for NMR-based plant seed metabolomic analysis with maximized polar metabolite extraction efficiency, signal-to-noise ratio, and chemical shift consistency
Authors: Wu Xiangyu , Li Ning , Li Hongde , Tang Huiru
Published: December 2013

An optimized method for NMR-based plant seed metabolomic analysis was established with extraction solvent, cell-breaking method and extract-to-buffer ratio.
Self-assembled monolayers of gold nanostars: a convenient tool for near-IR photothermal biofilm eradication
Authors: Pallavicini Piersandro , Donà Alice , Taglietti Angelo , Minzioni Paolo , Patrini Maddalena , Dacarro Giacomo , Chirico Giuseppe , Sironi Laura , Bloise Nora , Visai Livia , Scarabelli Leonardo
Published: December 2013

Self-assembled monolayers of gold nanostars exert efficient photothermal action againstS. aureusbiofilms upon laser irradiation in the nearIR.
Free-electron laser induced processes in thin molecular ice
Authors: Siemer Björn , Roling Sebastian , Frigge Robert , Hoger Tim , Mitzner Rolf , Zacharias Helmut
Published: December 2013

Intermolecular reactions in and on icy films on silicate and carbonaceous grains constitute a major route for the formation of new molecular constituents in interstellar molecular clouds. In more diffuse regions and in protoplanetary discs, energetic radiation can trigger reaction routes far from thermal equilibrium. As an analog of interstellar ice-covered dust grains, highly-oriented pyrolytic graphite (HOPG) covered with D2O, NO, and H atoms is irradiated by ultrashort XUV pulses and the desorbing ionic and neutral products are analysed. The yields of several products show a nonlinear intensity dependence and thus enable the elucidation of reaction dynamics by two-pulse correlated desorption.
Adjustment of carbon fluxes to light conditions regulates the daily turnover of starch in plants: a computational model
Authors: Pokhilko Alexandra , Flis Anna , Sulpice Ronan , Stitt Mark , Ebenhöh Oliver
Published: December 2013

Diurnal regulation of carbon fluxes in plants.
Spatially adaptive despeckling of SAR image using bivariate thresholding in directionlet domain
Authors: Sethunadh R. , Thomas T.
Published: December 2013

A novel spatially adaptive despeckling algorithm is presented for a synthetic aperture radar (SAR) image by taking into account the statistical interscale dependency of the directionlet transform (DT) coefficients. The DT is first computed along the dominant directions of the spatially segmented image. The signal and the noise coefficients are modelled using bivariate distributions which take into account the statistical dependence between the adjacent scale coefficients. The nonlinear threshold functions derived from the models employing a maximum a posteriori estimator are then used for estimating the noise‐free coefficients. The experimental results show that the proposed method outperforms similar methods in terms of numerical and perceptual quality.
Hybrid‐genetic‐algorithm‐based resource allocation for slow adaptive OFDMA system under channel uncertainty
Authors: Xu Lei , Li Yaping , Tang Zhen‐min
Published: December 2013

A resource allocation algorithm for the slow adaptive orthogonal frequency division multiple access system under channel uncertainty is considered. The optimisation objective maximises the long‐term system throughput over subcarrier assignment and the constraint condition satisfies the short‐term data rate requirements of individual users, except occasional outage. Such an objective has a natural chance‐constrained programming formulation. To solve the chance‐constrained optimisation, the neural network and the genetic algorithm (GA) are integrated to develop a hybrid GA (HGA) which could satisfy the user data rate requirement with the target outage probability. The simulation tests verify that the HGA yields a higher long‐term system throughput than the Li algorithm with the Bernstein approximation.
20 Gbit/s data transmission over 2 km multimode fibre using 850 nm mode filter VCSEL
Authors: Safaisini R. , Haglund E. , Westbergh P. , Gustavsson J.S. , Larsson A.
Published: December 2013

Error‐free data transmission over 1.3 and 2 km multimode fibre at 25 and 20 Gbit/s, respectively, is demonstrated using a high‐speed, single‐mode, 850 nm vertical‐cavity surface‐emitting laser (VCSEL) with an integrated mode filter. This result represents a bitrate‐distance product of 40 Gbit/s km, a new record for multimode fibre VCSEL‐based interconnects.
Indoor positioning based on received optical power difference by angle of arrival
Authors: Yang S.H. , Jeong E.M. , Han S.K.
Published: December 2013

An indoor optical wireless positioning system using a differential of power received by tilted multiple optical receivers is proposed. The proposed system is based on gain difference by angle of arrival with a fixed single optical transmitter that is a white light‐emitting diode. A demonstration shows that the proposed structure and algorithm estimates position successfully without requiring the characteristic information of the transmitter.
Two‐octave tunable liquid‐metal monopole antenna
Authors: Morishita A.M. , Kitamura C.K.Y. , Ohta A.T. , Shiroma W.A.
Published: December 2013

Liquid metal is used to tune the operational frequency of a monopole antenna by adjusting its length. The centre frequency can be continuously tuned over two octaves, 2.0–9.5 GHz, while maintaining a gain of ∼5.2 dBi.
Image layering based small infrared target detection method
Authors: Li Hang , Tan Yihua , Li YanSheng , Tian Jinwen
Published: December 2013

An image layering and confidence analysis based small target detection method in infrared image is proposed. First, a Huffman tree is used to refine the histogram curve, and the valleys of the refined curve are detected automatically. Then, the grey values of the detected valleys are recorded as the segmenting thresholds to stratify the original infrared image. After detecting small abnormal regions in each layer and defining them to be candidate targets, the candidate target set is composed of the candidate targets in all layers. Finally, the abnormality‐based confidence of each candidate target is calculated and sorted. The candidate target with maximum confidence is considered as the real one. The experiments show that the proposed method performs robustly and efficiently.
Meandered TWAs array for near‐field UHF RFID applications
Authors: Michel A. , Caso R. , Buffi A. , Nepa P. , Isola G.
Published: December 2013

An array of 2 × 2 travelling wave antennas (TWAs) is proposed for near‐field RFID applications in the UHF band (865–928 MHz). Each array element is characterised by a meandered line based on coplanar waveguide technology. All the TWAs end on a matched load, which allows for non‐stationary current and field distributions as well as a low far‐field gain. Thus, strong and uniform fields within a confined volume above the antenna surface have been obtained, with a field maximisation in the antenna central area, where tagged items are supposed to lie on. The meander geometry allows exciting all‐field components, making the tag detection almost independent of tag location and orientation when it lies on the antenna surface. Since TWAs are not resonating structures, the proposed antenna results are scalable, allowing for an easy integration in commercial readers with arbitrary sizes. In particular, a 275 × 135 × 10 mm3 antenna has been designed to fit a particular commercial desktop reader size. Measured tests on the antenna read range were carried out, showing a field distribution maximised in the broadside direction within 10 cm from the antenna surface.
Evaluation of average bit error rate for wireless networks with alpha‐stable interference
Authors: Aalo V.A. , Peppas K.P. , Efthymoglou G. , Alwakeel M. , Alwakeel S.
Published: December 2013

The performance of a digital wireless network that operates in a Rayleigh fading environment in the presence of Gaussian noise and heavy‐tailed impulsive interference that can be modelled by an α‐stable process is investigated. Such wireless networks include ad hoc or cognitive radio networks that operate in an unbounded fading/shadowing environment with a Poisson interference field. For the system under consideration, a novel closed‐form expression for the average bit error probability of digital modulation schemes, valid for any arbitrary real values of the characteristic exponent, α, is derived. The validity of the proposed formulation is attested through Monte Carlo simulation results.
Optimising no acknowledgment policy on WLANs supporting voice over internet protocol
Authors: Politis A. , Hilas C. S. , Papatsoris A. D.
Published: December 2013

The efficiency of the no acknowledgment policy, as defined by the IEEE 802.11e amendment, is analysed and an improvement modification to this mechanism is proposed for WLANs supporting voice over internet protocol.
Finding number of clusters in single‐step with similarity‐based information‐theoretic algorithm
Authors: Temel T.
Published: December 2013

A single‐step algorithm is presented to find the number of clusters in a dataset. An almost two‐valued function called cluster‐boundary indicator is introduced with the use of similarity‐based information‐theoretic sample entropy and probability descriptions. This function finds inter‐cluster boundary samples for cluster availability in a single iteration. Experiments with synthetic and anonymous real datasets show that the new algorithm outperforms its major counterparts statistically in terms of time complexity and the number of clusters found successfully.
60 GHz grounded‐coplanar‐waveguide‐to‐substrate‐integrated‐waveguide transition for RoF transmitters
Authors: Flammia I. , Khani B. , Arafat S. , Stöhr A.
Published: December 2013

A novel transition from a grounded‐coplanar waveguide to a substrate integrated‐waveguide (SIW) is presented featuring a fully planar bias tee for the development of 60 GHz radio‐over‐fibre photonic transmitters for indoor applications. The transition is intended to serve as a connection between a 60 GHz photodiode chip and SIW antennas suitable for indoor data distribution. Simulations show that in the whole 57–64 GHz communication band, the return loss (RL) is at least 15 dB, whereas the insertion loss (IL), is < 0.9 dB. Measurements of a back‐to‐back configuration confirm the numerical results, with a IL of ∼2 dB and a RL > 12 dB.
Coding schemes for multi‐level Flash memories that are intrinsically resistant against unknown gain and/or offset using reference symbols
Authors: Immink K.A.S.
Published: December 2013

Coding schemes for storage channels, such as optical recording and non‐volatile memory (Flash), with unknown gain and offset are presented. In its simplest case, the coding schemes guarantee that a symbol with a minimum value (floor) and a symbol with a maximum (ceiling) value are always present in a codeword so that the detection system can estimate the momentary gain and the offset. The results of the computer simulations show the performance of the new coding and detection methods in the presence of additive noise.
Low‐voltage bulk‐driven self‐biased cascode current mirror with bandwidth enhancement
Authors: Raj N. , Singh A.K. , Gupta A.K.
Published: December 2013

A low‐voltage, high‐performance, self‐biased, cascode bulk‐driven current mirror is proposed. Using the bulk‐driven technique together with quasi‐floating gate metal‐oxide semiconductor transistors improves the overall circuit performance. A small‐signal analysis validates the advantage of such an approach over conventional bulk‐driven circuits. The proposed circuit has four times smaller input resistance and extended bandwidth by about three times over the same configuration using the conventional bulk mechanism. The circuit is simulated on UMC 0.18 μm technology node with the help of HSpice.
Simplification of strip‐wise algorithms applied for two‐dimensional intersymbol interference detection
Authors: Lee Chang‐Ming , Wu Tsung‐Che , Lin Jian‐Ren
Published: December 2013

With the development of the high‐speed communication channel or high‐capacity storage device, the intersymbol interference (ISI) occurs more frequently in the condensed data. The traditional Bahl – Cocke – Jelineu – Raviv (BCJR) method is capable of solving the two‐dimensional (2D) symbol influence problem with extremely high cost. By analysing the complexity in terms of branch, state and path in the 2D trellis‐based ISI detection, the authors verify that the system complexity is mainly dominated by the window size. To reduce the detection complexity, the conventional simplifications are applied in the 2D strip‐wise ISI detection. In addition, a two‐phase strip‐wise detection is proposed to achieve a lower complexity than that of the conventional simplifications. In this system, the first detector can be realised by a low‐complexity method (like the hard detection or Viterbi algorithm) to provide the mask shrinking with predicted data. After reducing the mask size, the second detector can detect the main portion of ISI by the trellis‐based detection (like BCJR algorithm) with a small mask. Under the similar detection performance, the proposed scheme can achieve more than 91.76% saving in the metric computation compared with the 5 × 3‐window IRCSDFA (iterative row–column soft‐decision feedback algorithm) simplified by the M‐algorithm with M = 8.
Installed capacity selection of hybrid energy generation system via improved particle‐swarm‐optimisation
Authors: Wai Rong‐Jong , Cheng Shan , Lin Yeou‐Fu , Chen Yi‐Chang
Published: December 2013

In this study, an improved particle‐swarm‐optimisation (IPSO) method with dynamically changing inertia weight and acceleration coefficients is employed in determining the installed capacity selection of a hybrid energy generation system (HEGS). The studied HEGS, which includes wind power, photovoltaic (PV) and fuel cells, is used to suppress the penalty bill caused by exceeding the contract power capacity with the power company and to supply the backup power when needed. The objective is to achieve the optimal ratio of the installed capacity of the HEGS, so that each energy source can make the best contribution in the system, satisfy the load demand at a minimal installation cost and shorten the payback period. To realise this objective, the payback period is selected as the optimisation objective function by considering the installation cost and cost recovery. In the IPSO, the penalty technique is designed to solve the optimisation problem with equality and inequality constraints for updating the particle's position and its global best position. The proposed IPSO algorithm has been examined, tested and compared with other methods on the optimisation problem and proven to be more efficient in searching the global solution through numerical simulations of a real case.
Data‐mining‐based intelligent anti‐islanding protection relay for distributed generations
Authors: Kar Susmita , Samantaray Subhransu R.
Published: December 2013

A data‐mining‐based intelligent anti‐islanding detection scheme for distributed generation (DG) protection has been presented. The process starts at deriving highly involved features using discrete Fourier transform‐based pre‐processor at the DG end. The features derived include both positive and negative sequence quantities and related features. Once the features are retrieved, the decision tree is trained to build a data‐mining model for identifying the islanding events from non‐islanding situations, including disturbances close to islanding conditions. The proposed anti‐islanding relay is extensively tested on simulation model and provides encouraging results considering wide variations in operating conditions. Further, the validation is extended on real‐time digital simulator module to test the efficacy of the proposed anti‐islanding relay. The test results indicate that the proposed anti‐islanding relay can reliably detect islanding conditions while meeting the speed criteria.
Approach for modelling trust in cluster‐based wireless ad hoc networks
Authors: Chatterjee Pushpita , Ghosh Uttam , Sengupta Indranil , Ghosh Soumya K.
Published: December 2013

In this study, the authors propose a cluster‐based trust management model that efficiently detects the malicious nodes and restricts them to be on a route in wireless ad hoc networks. In contrast to previous works, the trust of a node is calculated using various trust attributes having substantial effect on reliable routing in the networks. In the proposed model, each node periodically predicts the value of each trust attribute about other nodes using autoregression. Subsequently, the direct trust is estimated using the weighted combination of trust attributes and it is fine tuned using proportional–integral model. All these recommendation trusts, from common neighbours, are collected and combined by the clusterhead to quantify the trust, and hence the routing is reliable and secure in the proposed model. Simulation results show that the proposed trust model provides better throughput and packet delivery ratio in presence of malicious nodes compared to other existing schemes.
Control loop design of sequential switching shunt regulator considering the influence of double section functioning
Authors: Li Fang , You Xiaojie , Li Yan
Published: December 2013

Sequential switching shunt regulator (S3R) has been widely used in satellites for its simple structure and high reliability. Double section functioning, which has two sections operating simultaneously, is the other operating mode of S3R beside the normal mode. It is inevitable and can lead to larger bus voltage ripple, less controllability and higher switching losses. A detailed analysis based on the double section functioning process description is given on the boundary load current, the main bus voltage ripple and the switching frequency. Considering the influence of double section functioning, a new method of control loop design of S3R is proposed based on the small single mathematical model. A 4.5 kW S3R prototype is built to verify the control loop design, and the load region of double section functioning can be limited as designed.
Minimum signal modulation scheme based on a single carrier for interleaved operation of parallel phase legs in voltage source converters
Authors: Capella Gabriel J. , Gabiola Igor , Pou Josep , Zaragoza Jordi , Ceballos Salvador , Agelidis Vassilios G.
Published: December 2013

Connecting legs in parallel is a common way to increase the output current of a power converter. Interleaving the carriers used to modulate the reference signals for each leg leads to a reduction in the output current ripple without resorting to increasing the switching frequency. A whole set of shifted carriers is required if interleaved pulse‐width modulators (PWMs) are used. Implementing this by means of a digital signal processor (DSP) means that the higher the number of carriers, the higher the number of DSP timing resources required. Provided that the latter are usually limited, this could be a drawback when increasing the number of interleaved carriers. This study presents the implementation of a PWM scheme where all modulators use the same carrier offering the same results as if a set of n interleaved carriers were used. Since the proposed algorithm takes maximum benefit from the PWM units available in a DSP, a higher number of legs connected in parallel can be controlled without adding any external processing hardware. A MATLAB/Simulink model has been set up for simulation purposes. Selected experimental results obtained from a three‐leg single‐phase inverter are reported, confirming the effectiveness of the proposed implementation.
Utilisation of alkaline electrolysers to improve power system frequency stability with a high penetration of wind power
Authors: Kiaee Mahdi , Cruden Andrew , Infield David , Chladek Petr
Published: December 2013

Controlling the frequency of power systems with high wind power penetration is more difficult due to the high variability of the wind power. One possible mainstream energy carrier in the future, particularly for the transportation sector, is Hydrogen, and water electrolysis is one of the most attractive ways to produce it. In this study, a detailed model of a steam turbine generator has been produced in MATLAB Simulink and used to investigate a scenario in which there is a 25% penetration of wind power. To improve the frequency stability of the power system, large scale alkaline electrolysers used in future Hydrogen filling stations could adjust their load with respect to the frequency deviation from nominal and can significantly reduce fluctuations in system frequency. For the case examined, five times less spinning reserve is required in order to maintain the power system frequency within operational limits when electrolysers are utilised as a form of demand side management (DSM), compared to the base case where no electrolyser DSM plant is available. Actual operational data from a pressurised alkaline electrolyser is used to evidence the fast load changing capability of such electrolysers.
Direction of arrival estimation performance comparison of dual cancelled channels space–time adaptive processing techniques
Authors: Colone Fabiola , Cristallini Diego , Cerutti‐Maori Delphine , Lombardo Pierfrancesco
Published: December 2013

This study presents two alternative techniques for the estimation of the target direction of arrival (DOA) for a moving radar equipped with digital beamforming, operating in look‐down against strong clutter echoes. Both the considered techniques, namely AB space–time adaptive processing (AB‐STAP) and generalised monopulse estimator, are based on a dual cancelled channel approach that simplifies their implementation. An extensive performance comparison is presented for the ground moving targets. Both the theoretical and simulated analyses of DOA estimation are performed, which include the comparison to the Cramér‐Rao bound. The considered processing schemes are shown to yield comparable accuracies in target DOA estimation with respect to a maximum likelihood estimator. Moreover, they ensure lower computational cost, since no numerical maximisation of any functional is required. AB‐STAP shows the additional nice property of estimation robustness when a limited set of homogeneous data is available to achieve the adaptivity. The comparison is finally performed applying the different estimators to a set of real multichannel data.
Synthesis of well‐dispersed copper nanoparticles in electrospun polyacrylonitrile nanofibres
Authors: Xu Tong , Li Chunping , Li Hongqiang , Bai Jie , Qin Haili , Sun Weiyan
Published: December 2013

Copper (Cu) containing composite nanofibres was prepared by electrospinning and the high‐pressure hydrogenation method. Copper nitrate has been mixed in the polymeric precursor solution before electrospinning. The nanofibres were characterised by using scanning electron microscopy, UV–vis spectroscopy, energy dispersive spectroscopy, transmission electron microscopy and X‐ray photoelectron spectroscopy. The observations revealed the embedding of polyacrylonitrile (PAN) nanofibres with Cu nanoparticles. It was also found that Cu nanoparticles were significantly protected by PAN nanofibres. The combination of electrospinning and the high‐pressure hydrogenation method will provide a new approach to producing the functional materials with various applications.
Developing integrated piezoelectric direct current sensor with actuating and sensing elements
Authors: Wang Dong F. , Suzuki Yasuhiro , Kobayashi Takeshi , Itoh Toshihiro , Maeda Ryutaro
Published: December 2013

A cantilever‐based, oscillating type MEMS direct current sensor (abbreviated as DC sensor), integrated with both actuating and sensing piezoelectric plates, as well as a micromagnet is proposed to satisfy the increasing needs of DC power supply for monitoring electrical consumption by either a single‐wire or two‐wire appliance cord. A prototype MEMS DC sensor, with a measured resonant frequency of 23 Hz, was microfabricated and characterised. In the case of a two‐wire electrical appliance cord, it was found that the change in the peak‐to‐valley value (abbreviated as P‐V value) of the output voltage was approximately proportional to the applied DC, and increased from 10.4 to 43.2 mV when the DC increased from 0 to 2 A under an excitation voltage of 5 Vpp. The shift of the resonant frequency because of the applied DC is believed to account for the change in the P‐V value (or the maximum value) of the output voltage. In summary, the proposed MEMS DC sensor integrated with both actuating and sensing piezoelectric plates was observed to measure the output voltage constantly and linearly over the applied DC directly in a two‐wire appliance without using a cord separator.