bluuebunny/crossref_metadata_2025 huggingface dataset:
NADPH oxidases and cancer
Authors: Roy Krishnendu , Wu Yongzhong , Meitzler Jennifer L. , Juhasz Agnes , Liu Han , Jiang Guojian , Lu Jiamo , Antony Smitha , Doroshow James H.
Published: March 2015

The mechanism by which reactive oxygen species (ROS) are produced by tumour cells remained incompletely understood until the discovery over the last 15 years of the family of NADPH oxidases (NOXs 1–5 and dual oxidases DUOX1/2) which are structural homologues of gp91phox, the major membrane-bound component of the respiratory burst oxidase of leucocytes. Knowledge of the roles of the NOX isoforms in cancer is rapidly expanding. Recent evidence suggests that both NOX1 and DUOX2 species produce ROS in the gastrointestinal tract as a result of chronic inflammatory stress; cytokine induction (by interferon-γ, tumour necrosis factor α, and interleukins IL-4 and IL-13) of NOX1 and DUOX2 may contribute to the development of colorectal and pancreatic carcinomas in patients with inflammatory bowel disease and chronic pancreatitis, respectively. NOX4 expression is increased in pre-malignant fibrotic states which may lead to carcinomas of the lung and liver. NOX5 is highly expressed in malignant melanomas, prostate cancer and Barrett's oesophagus-associated adenocarcinomas, and in the last it is related to chronic gastro-oesophageal reflux and inflammation. Over-expression of functional NOX proteins in many tissues helps to explain tissue injury and DNA damage from ROS that accompany pre-malignant conditions, as well as elucidating the potential mechanisms of NOX-related damage that contribute to both the initiation and the progression of a wide range of solid and haematopoietic malignancies.
“You Can Lead a Horse to Water …”: Focus Group Perspectives on Initiating and Supporting Hearing Health Change in Older Adults
Authors: Holliday Heather V. , Jenstad Lorienne M. , Grosjean Garnet , Purves Barbara
Published: March 2015

Purpose

The aim of this study was to use focus group discussions to (a) evaluate the use of an educational presentation as an impetus for hearing health change and (b) investigate hearing health from the perspective of older adults.

Method

Twenty-seven (4 men, 23 women) community-dwelling older adults attended 4 data collection events. Participants attended a presentation titledHearing Health in Older Adults,which was delivered by a trained presenter in a peer-teaching-peer format. Following each presentation, a focus group discussion took place. Digital audio recordings, field notes, and memos of the discussions were used to create verbatim transcripts. Data were analyzed using qualitative description and thematic analysis techniques.

Results

Five central themes emerged when older adult focus groups discussed the presentation and hearing health change: recognizing and admitting, understanding the options, sharing stories and experiences, barriers and facilitators, and the presentation.

Conclusion

Facilitators to hearing health change identified by participants include widespread education about hearing health; clarification about roles, professional motivation, and cost in hearing care; and opportunities to learn from and share personal stories with peers.
A Meta-Analysis of Cross Sectional Studies Investigating Language in Maltreated Children
Authors: Lum Jarrad A. G. , Powell Martine , Timms Lydia , Snow Pamela
Published: March 2015

Purpose

In this review article, meta-analysis was used to summarize research investigating language skills in maltreated children.

Method

A systematic search of published studies was undertaken. Studies were included in the meta-analysis if they investigated language skills in groups comprising maltreated and nonmaltreated children. Studies were selected if these 2 groups of children were of comparable age and from a similar socioeconomic background.

Results

A total of 26 studies were identified that met the inclusion criteria. Results from the meta-analysis showed that maltreated children demonstrated consistently poorer language skills with respect to receptive vocabulary (
k
= 19; standardized mean difference [SMD] = .463; 95% confidence interval [CI; .293, .634];
p
< .001), expressive language (
k
= 4; SMD =.860; 95% CI [.557, 1.163];
p
< .001), and receptive language (
k
= 9; SMD =.528; 95% CI [.220, .837];
p
< .001).

Conclusion

Together, these results indicate a reliable association between child maltreatment and poor language skills.

Supplemental Material

https://doi.org/10.23641/asha.6170318
High‐efficiency millimetre‐wave spatial power combining structure
Authors: Ding Jinyi , Wang Qingyuan , Zhang Yunbo , Wu Liang , Sun Xiaowei
Published: March 2015

A high‐efficiency millimetre‐wave spatial power combining structure that is a waveguide power combining network is proposed. High phase and amplitude consistency and isolation between the output ports are the key factors for the high‐efficiency power combining structure. The phase and amplitude consistency is guaranteed by the symmetry of this structure. As a sample, an eight‐way power splitting and combining network in the Ka‐band is designed, fabricated and measured. In a fractional bandwidth of 20% around a centre frequency of 33 GHz, the measured results show that the phase and amplitude differences between the output ports are smaller than ±1.5° and ±0.1 dB, isolation between the output ports is higher than 17 dB, insertion loss is lower than 0.1 dB, and the return loss of the input and output ports is better than 18 dB. The proposed broadband eight‐way power combining network can improve the spatial power combining efficiency to a great extent with excellent performance.
Frequency estimation for compact microstrip antennas
Authors: Casado F. , Arriola A. , Arruti E. , Ortego I. , Sancho J.I.
Published: March 2015

A simple method is presented for estimating the resonant frequency of compact slotted microstrip antennas, based on their current distribution. The method has been first tested in two basic and symmetric geometries; afterwards, through the combination of these geometries, a multi‐slotted structure has been analysed. Prototypes have also been manufactured in RT/Duroid 6002 and FR4 substrates, and good agreement has been obtained between estimations, simulations and measurements. A maximum estimation error of 10% has been achieved with this method, providing a useful tool for the design of compact slotted microstrip antennas.
Compact multilayer self‐packaged filter with surface‐mounted packaging
Authors: Ma K. , Fan L. , Zhang S.
Published: March 2015

A new self‐packaged bandpass filter by using multilayer print circuit board technology is proposed and investigated. By using a multilayer structure, a lumped step‐impedance resonator as well as self‐packaging, the designed filter can achieve a much more compact size, low insertion loss and a wide stopband. The implemented filter operated at a centre frequency of 800 MHz with a 3 dB bandwidth of 120 MHz demonstrates stopband rejection better than 25 dB up to 4 GHz. The measured insertion loss including the connector loss in the input and output is 1.48 dB. The size of the filter is only 12 × 8 mm, i.e. 0.059λg × 0.039λg.
Gallium arsenide antireflection layer via direct wet thermal oxidation
Authors: Li J. , Tian Y. , Hall D.C.
Published: March 2015

Broad bandwidth, low‐reflectance, low‐cost antireflection (AR) layers on GaAs are demonstrated using a quarter‐wave optical thickness dielectric grown by directly oxidising the GaAs through a carefully‐balanced oxygen‐enhanced wet thermal process at 420°C. For centre design wavelengths between 550 and 800 nm, the native oxide AR layers have a simulated and measured reflectance minima as low as 1.0%, with reflectance <10% over bandwidths as large as 342 nm. The experimental reflectance spectra agree well with the modelling based on the complex optical constants obtained by variable angle spectroscopic ellipsometry, and are consistent with the low GaAs native oxide surface roughness (<0.3 nm) and interface roughness (<2.3 nm) measured by atomic force microscopy.
Compact tunable bandpass filter with wide tuning range using ring resonator and short‐ended coupled lines
Authors: Zhu H. , Abbosh A.
Published: March 2015

A tunable bandpass filter with wide tuning ranges for both the centre frequency and bandwidth is presented. The filter is based on using a ring resonator connected to a short‐ended coupled‐line structure. Two transmission zeros are generated in the upper stopband resulting in a sharp cutoff and harmonic suppression across a wide stopband. A thorough procedure is used to analyse the proposed filter. A prototype is fabricated and tested. The achieved results indicate a wide centre frequency and bandwidth tuning ranges of 0.52–1.42 GHz and 90–320 MHz, respectively.
Planar ultra‐wideband printed wide‐slot antenna using fork‐like tuning stub
Authors: Arya Ashwini K. , Aziz Rao Shahid , Park Seong‐Ook
Published: March 2015

A printed wide‐slot antenna with a centred rectangular parasitic patch, fed by a fork‐like tuning stub with rectangular parasitic elements adjacent to the main feed line is proposed and discussed. The proposed wide‐slot antenna eliminates the need of rotation of the slot and parasitic patches both in the ground plane for the improvement in impedance bandwidth. The experimental results indicate that the presented antenna has a bandwidth (−10 dB) of more than 148% ranging from 2 to 13.5 GHz. The total size of the proposed antenna configuration is 44.3 × 44.3 × 0.508 mm3.
Paired‐relay‐selection schemes for two‐way relaying with network coding
Authors: Jiang Yunxiang , Lau Francis Chung Ming , Sattar Zeeshan , Ho Ivan Wang‐Hei , Zhou Qing Feng
Published: March 2015

To exchange information between two sources in a two‐way relaying network with multiple potential relays, most researches focus on two‐hop relay system with single‐relay‐selection (SRS) scheme. Comparing with SRS scheme, the authors first design a paired‐relay‐selection (PRS) scheme in which a pair of ‘best’ relays broadcast network‐coded information to other nodes (source or relay). They propose an optimal selection algorithm and a suboptimal algorithm that selects the pair of ‘best’ relays in the PRS scheme and they describe how the nodes exchange information in a frame consisting of four timeslots. Both the analytical and simulation results show that when the pathloss exponent is large and/or there is a sufficient number of relays to choose from, using two relay nodes can provide a lower outage compared with using only one relay node even under the same total transmit power in uniformly distributed relay networks. In addition, to reduce the overhead of the PRS scheme, they propose an iterative‐PRS (I‐PRS) scheme in which the paired relay is selected in an iterative and opportunistic way. Simulation results show that the I‐PRS scheme has nearly the same outage performance as the PRS scheme under time‐invariant channels and significantly outperforms the PRS scheme under time‐varying channels.
Interference‐leakage based non‐cooperative beamforming with low‐dimensional approximation
Authors: Choi Jinho
Published: March 2015

In this study, the authors have studied downlink multiuser non‐cooperative beamforming in a time‐division duplexing‐based multicell system with a non‐linear Jacobi‐like iterative algorithm, where each base station is to minimise the interference leakage to adjacent cells in forming beams with signal‐to‐interference‐plus‐noise ratio constraints for users in its cell. The resulting approach is referred to as altruistic non‐cooperative beamforming (ANB). To reduce the computational complexity for ANB per cell, a low‐dimensional beamforming approach, which can be easily solved as it has a standard downlink multiuser beamforming formulation, has also been considered at the expense of degraded performance.
Downlink massive distributed antenna systems scheduling
Authors: Sun Qiang , Jin Shi , Wang Jue , Zhang Yuan , Gao Xiqi , Wong Kai‐Kit
Published: March 2015

This study investigates the scheduling problem for a single‐cell downlink distributed antenna systems (DASs) with a massive number of remote access units (RAUs). To reduce signalling overhead under limited backhaul capacity, the authors make use of local long‐term channel state information (CSI) in coordinated scheduling design. They first derive the ergodic rate expressions for both the single RAU transmission and the cooperative RAU transmission modes as functions of long‐term CSI. Then greedy scheduling algorithms (GSAs) aiming for the maximum ergodic sum rate for the massive DAS using long‐term CSI are proposed. To mitigate the intra‐cell interference, a two‐stage GSA with hybrid transmission mode is devised. Asymptotic analysis reveals that as the number of RAUs goes to infinity, intra‐cell interference can be effectively mitigated. Simulation results verify the analysis and demonstrate that the two‐stage GSA exhibits a higher ergodic sum‐rate.
Cooperative space‐time block coded full‐duplex relaying over frequency‐selective channel
Authors: Jeon Sungho , Han Jae‐Shin , Choi Jeong‐Min , Seo Jong‐Soo
Published: March 2015

In this study, the authors investigate a distributed time‐reversal space‐time block coded (D‐TR‐STBC) system with amplify‐and‐forward full duplex relaying (FDR) over frequency‐selective channel. In the first, they present an FDR to use in a cooperative D‐STBC relaying in which a relay transmits the delayed signal as much as one frame in order to maintain the orthogonal property of STBC at the destination. Then, they briefly present the conventional full self‐interference cancellation (SIC) which continuously removes the self‐interference signal. As an alternative to the full SIC, they further introduce a partial SIC that periodically performs the SIC process. As a result, it can reduce cancellation processing by a half time compared to the full SIC. In the second, they propose the efficient and yet optimal destination structure consisting of the forward interference cancellation (IC), backward IC and joint equalisation and data combining in order to obtain a full coding gain. It is shown that the proposed D‐TR‐STBC‐FDR system has ∼3 dB signal‐to‐noise ratio gain compared to cooperative half‐duplex relaying with D‐TR‐STBC while it has the same diversity order. In addition, they show that there are no performance losses between FDR with full SIC and FDR with partial SIC.
Myopic policy for opportunistic access in cognitive radio networks by exploiting primary user feedbacks
Authors: Wang Kehao , Liu Quan , Li Fangmin , Chen Lin , Ma Xiaolin
Published: March 2015

The authors consider a cognitive radio network overlaying on top of a legacy primary network in which a secondary user is allowed to access primary channel by overhearing feedback signals over the primary channels. Each channel is assumed to be a two state Makovian process. Aiming at maximising the expected accumulated discounted network throughput, the considered sequential decision‐making problem can be cast into a restless multi‐armed bandit (RMAB) problem which is well‐known to be PSPACE‐hard, and thus a natural alternative approach is to seek a simple myopic policy. This study presents a theoretical study on the optimality of the proposed myopic policy for the special RMAB problem by considering four different cases: negatively correlated homogeneous channels, heterogeneous channels, positively correlated heterogeneous channels and negatively correlated heterogeneous channels. More specifically, the authors establish the closed‐form conditions to guarantee the optimality of the myopic policy for the four cases, respectively, which, combined with the case of positively correlated homogeneous channels, constitute a complete paradigm for the optimality of the myopic policy.
Data‐driven predictive direct load control of refrigeration systems
Authors: Shafiei Seyed Ehsan , Knudsen Torben , Wisniewski Rafael , Andersen Palle
Published: March 2015

A predictive control using subspace identification is applied for the smart grid integration of refrigeration systems under a direct load control scheme. A realistic demand response scenario based on regulation of the electrical power consumption is considered. A receding horizon optimal control is proposed to fulfil two important objectives: to secure high coefficient of performance and to participate in power consumption management. Moreover, a new method for design of input signals for system identification is put forward. The control method is fully data driven without an explicit use of model in the control implementation. As an important practical consideration, the control design relies on a cheap solution with available measurements than using the expensive mass flow meters. The results show successful implementation of the method on a large‐scale non‐linear simulation tool which is validated against real data. The performance improvement results in a 22% reduction in the energy consumption. A comparative simulation is accomplished showing the superiority of the method over the existing approaches in terms of the load following performance.
Comparison of the existing tool localisation methods on two‐dimensional ultrasound images and their tracking results
Authors: Zhao Yue , Liebgott Hervé , Cachard Christian
Published: March 2015

Over the last decade, different micro‐tool navigation and localisation algorithms have been developed. They can be divided into three groups: the eigen‐decomposition methods such as principal component analysis (PCA), the transform methods such as Hough transform (HT) and the space random iteration methods such as the random sample consensus (RANSAC) algorithm. To suppress the speckle noise of the ultrasound image, different noise suppression methods are also proposed. In this article, different combinations of preprocessing methods and localisation methods are compared. A tracking system is also developed to adapt these localisation methods to a dynamic situation. So far, the line‐filter method has achieved the best contrast ratio, and the threshold method requires the shortest time. These two preprocessing methods are proposed in the localisation algorithm and the tracking system. Simulations and experiments were conducted to verify the combinations of the localisation and tracking results. In static localisation, the line‐filter+RANSAC method achieves the highest localisation accuracy. In the dynamic situation, the PCA method achieves the highest tracking accuracy. In the real‐time evaluation, the calculation time of the RANSAC algorithm is the shortest. To satisfy the demand for localisation accuracy and calculation time, the line‐filter+RANSAC algorithm is the best choice.
Sequence‐to‐sequence alignment using a pendulum
Authors: Pribanic Tomislav , Lelas Marko , Krois Igor
Published: March 2015

Analysing two or more video sequences of dynamic scenes typically requires time synchronisation between sequences, where this alignment is not always possible using hardware. A particular method will most likely process the entire, frequently lengthy, imaged material, requiring additional processing which normally serves for synchronisation only. Software‐based synchronisation methods impose, in basically all cases, certain assumptions about an imaged three‐dimensional (3D) scene and are suited for the already imaged video material in the past. The authors argue that there are applications where the unsynchronised video sequences have not yet been taken. The time‐efficient solution uses a pendulum consisting of a small ball, attached to a 50 cm string and suspended from a pivot so that it can swing freely. The authors estimate the time instant when the ball swings through the equilibrium position. The difference in these times for two cameras yields a subframe time difference between cameras. The proposed method yields subframe differences, statistically no different from ground truth data. 3D reconstruction results for synchronised data clearly outperform those which are unsynchronised. The proposed method relaxes any restrictions and assumptions about the 3D scene that will be imaged later on, yet it allows accurate subframe synchronisation in less than a second.
Cross‐view face recognition via structured dictionary based domain shift
Authors: Chen Xue , Wang Chunheng , Xiao Baihua , Cai Xinyuan
Published: March 2015

View variation is a major challenge in face recognition. In this study, the authors propose a novel cross‐view face recognition method by seeking potential intermediate domains between the source and target views to model the connection of varying‐views faces. Specifically, each intermediate domain is associated with a dictionary subspace. Learning proceeds in two phases. First, the authors discriminatively train a sub‐dictionary for each subclass of data, which then compose a structured dictionary of powerful reconstructive and discriminative capability on the source data. Secondly, the authors gradually adapt the source domain dictionary to the target domain by incrementally reducing the reconstruction error on the target data, which forms a smooth transition path connecting the source and target domains. Instead of updating the structured dictionary integrally, the authors develop a refined sub‐dictionary‐based updating algorithm, which makes the intermediate dictionaries fit on the target data better and faster. Finally, the authors apply invariant sparse codes across the source, intermediate and target domains to render domain‐shared representations, where the sample differences caused by view changes are reduced. Experiments on the CMU‐PIE and Multi‐PIE dataset demonstrate the effectiveness of the proposed method.
Sectionalising methodology for parallel system restoration based on graph theory
Authors: Quirós‐Tortós Jairo , Panteli Mathaios , Wall Peter , Terzija Vladimir
Published: March 2015

Parallel power system restoration (PPSR) restores isolated sections (islands) of the network in parallel, thus the overall restoration process is accelerated. These islands are defined during the preparation stage of PPSR as part of a sectionalising strategy (SS). During this process, it is important that the operators only use updated post‐blackout system information. This study proposes a new methodology based on the ‘cut‐set’ matrix defined in graph theory, which can identify a shortlist of suitable SSs that satisfy the critical PPSR constraints in a few minutes. This short list of SSs, not identified in previous works, can be presented to the operators to help them select a restoration plan that is tailored to the specific changes in topology and asset availability that the blackout has caused. The methodology is illustrated using the IEEE 9‐bus system, and validated using the IEEE 118‐bus and the Polish 3375‐bus system to demonstrate the efficiency of the new approach for large‐scale networks. Multiple case studies are developed to demonstrate the adaptability of the methodology to different system conditions, for example, the unavailability of assets. In every case, the methodology quickly identified a number of SSs that create suitable islands for parallel restoration.
Anisotropic adaptive method for triangular meshes smoothing
Authors: El Ouafdi Ahmed Fouad , El Houari Hassan , Ziou Djemel
Published: March 2015

Even with the advancing laser scanner technology, the digital objects are inevitably corrupted with random noise during the acquisition process. Many algorithms, regardless of principle, share the same basic idea of noise reduction through mesh smoothing. Smoothing can be performed locally, as in the anisotropic filtering by calculus of variations; or by smoothing mesh attributes such as normal vector and then adjusting vertex positions. In this study, the authors propose a novel algorithm based on the statistical distribution noise for anisotropic mesh smoothing. In this approach, the probability density function of the noise is first estimated, and then the anisotropic smoothing operation is performed through the diffusion tensor that allows to preserve mesh characteristics like edges, corner and ridges. The proposed algorithm is easy to implement and is thus suitable for real‐time noise reduction application.
Reversible data hiding in JPEG images utilising zero quantised coefficients
Authors: Nikolaidis Athanasios
Published: March 2015

A novel technique for data hiding in JPEG images is proposed. The technique relies on modification of zero quantised coefficients in each image block, in contrast to most previously proposed methods which also affect non‐zero coefficients and/or the quantisation tables. Both embedding and extraction are performed on a per‐block basis, without the need to preprocess the whole image. The proposed technique provides significantly lower distortion for similar embedding capacity, compared with recent state‐of‐the‐art techniques.
Vehicle logo recognition by weighted multi‐class support vector machine ensembles based on sharpness histogram features
Authors: Xiao Jianli , Xiang Wenshu , Liu Yuncai
Published: March 2015

Classical methods recognise vehicle logos with image feature matching approaches. Different from these methods, this study proposes a novel algorithm to recognise the vehicle logos in real time by constructing the weighted multi‐class support vector machine (SVM) ensemble model to classify the vehicle logos based on sharpness histogram features. To evaluate the performance of the proposed algorithm, extensive experiments have been performed. Experimental results indicate that the sharpness histogram features proposed by the authors has better distinguishability than colour histogram features. Moreover, they show that the proposed algorithm has the best average recognition performance, and its performance is the most robust. Conveniently, the proposed algorithm can avoid the burden of choosing the appropriate kernel function and parameters comparing with multi‐class SVM model.
Outlier detection in traffic data based on the Dirichlet process mixture model
Authors: Ngan Henry Y.T. , Yung Nelson H.C. , Yeh Anthony G.O.
Published: March 2015

Traffic data collections are exceedingly useful for road network management. Such collections are typically massive and are full of errors, noise and abnormal traffic behaviour. These abnormalities are regarded as outliers because they are inconsistent with the rest of the data. Hence, the problem of outlier detection (OD) is non‐trivial. This paper presents a novel method for detecting outliers in large‐scale traffic data by modelling the information as a Dirichlet process mixture model (DPMM). In essence, input traffic signals are truncated and mapped to a covariance signal descriptor, and the vector dimension is then further reduced by principal component analysis. This modified signal vector is then modelled by a DPMM. Traffic signals generally share heavy spatial‐temporal similarities within signals or among various categories of traffic signals, and previous OD methods have proved incapable of properly discerning these similarities or differences. The contribution of this study is to represent real‐world traffic data by a robust DPMM‐based method and to perform an unsupervised OD to achieve a detection rate of 96.67% in a ten‐fold cross validation.
Impact of ITS on CO2 emissions – the contribution of a standardised assessment framework
Authors: Wolfermann Axel , Gade Kay , Jonkers Eline
Published: March 2015

Intelligent transport systems are accepted as an integral part of the transport system. They have high potential in reducing the carbon footprint of traffic while improving efficient and safe transport. The calculation of CO2 emissions arising from the transport sector incorporating the impact of ITS is a challenging task. A systematic assessment methodology will support developers, public authorities and investors in ITS solutions to make sound decisions based on comparable and transparent impact estimates. As the basis for such an assessment, the fragmentation of traffic in underlying processes is suggested. These processes can be divided into transport demand related processes and driver behaviour and vehicle related processes. Together these processes lead to traffic flow. Transport processes are influenced by various factors. Both the processes itself and the factors influencing them can be affected by ITS. A systematic analysis of the potential effects of ITS on all these levels is the prerequisite for choosing a suitable modelling approach to quantify the effects. It also ensures the transparency of the modelling process by elucidating the required model sensitivities. The details of such an approach and its context from user need to a standardised assessment methodology for ITS is described.
Assessing the performance of a charge‐while‐driving system in urban arterial roads: insight from a microsimulation model
Authors: Deflorio Francesco , Castello Luca
Published: March 2015

This study presents a method based on traffic microsimulation to support feasibility studies on charge‐while‐driving (CWD) systems for fully electric vehicles in urban environments. The examined CWD solution is deployed by charging zones (CZs), which are installed before the stopping lines at signalised intersections. The opportunity to charge an electric vehicle en route is provided for almost stationary vehicle conditions, when it may be in queue for junction control requirements. The analysed scenario refers to a 2 km urban arterial with eight signalised intersections, where 10% of the traffic is assumed to be electric vehicles. CWD performance results are reported from the viewpoints of both driver and energy provider. The estimated stop time for electric vehicles at any section can vary and is often below 30 s. However, the entire stop time for a vehicle along the arterial is higher: ∼50% of the vehicles can charge in a range of 10–65 s. For the energy operator's viewpoint, a support analysis for the CZ location was performed by observing the charging opportunities at various sections. Finally, the total electric power provided for the entire system is estimated.
Analysing traffic fluency from bus data
Authors: Syrjärinne Paula , Nummenmaa Jyrki , Thanisch Peter , Kerminen Riitta , Hakulinen Esa
Published: March 2015

The use of stored public transportation data facilitates the identification of potential issues with urban traffic flow. Focusing on buses, the authors proceed from a city‐level delay distribution analysis to a detailed understanding of the factors that cause the delays on an example bus line. First, a database of bus data in Tampere was mined to detect any regular patterns in the distribution of delays in time, location or according to bus line throughout the city. The results allow the authors to focus on those areas and lines which are most prone to delays. In a case study, they illustrate that the most important reasons for tardy journeys are the long waiting times at traffic signals and bus stops, rather than slow driving speeds. The results are then further deepened to show spatially on a map which bus stops and intersections tend to be the ones where the time variances are high. The same methods can be applied to any other city for which the same kind of data are available.
Future role of cost–benefit analysis in intelligent transport system‐research
Authors: Schulz Wolfgang , Geis Isabella
Published: March 2015

For a successful implementation of intelligent transport systems (ITS), technological progresses and innovations are undisputable important. Nevertheless, economic viability may not be forgotten as a prerequisite. Considerable investments for stakeholders (such as public or industry) are needed to equip vehicles, install the necessary infrastructure or to set up traffic management centers. This study enhances the technological perspective on ITS‐projects by picking up the topic of economics. In this study, viable business models are acknowledged as a central success factor for the implementation of ITS. The focus, however, lies on the often neglected socio‐economic perspective which includes societal costs and benefits. These impacts can be determined with a cost–benefit analysis (CBA). On the basis of a systematic case study, this study provides a profound understanding for the methodology of the CBA and the importance for public‐decision making. By means of ITS‐projects of the European Framework Programs, the automotive ITS‐project simTD and the multimodal‐related project All Ways Travelling, the significance of CBA‐results for ITS‐projects is shown. At the same time, the method is critically assessed by showing a number of limitations that can strongly determine the validity of the results, and therefore require a methodological adaption to the needs of ITS‐projects.
Adaptive fine pollutant discharge control for motor vehicles tunnels under traffic state transition
Authors: Tan Zhen , Xia Yingjie , Yang Qinmin , Zhou Guomin
Published: March 2015

Traffic flow dynamics is an important issue for implementing effective pollutant discharge control of tunnels. Longitudinal ventilation using jet fans is the most popular system for pollutant discharge control of tunnels. Nowadays, jet fans equipped with the frequency conversion technology in the tunnel can shorten the control cycle and even conduct manipulation of step‐less jet speeds. The longitudinal ventilation system has considerable inertia and non‐linear characteristics, which are partly resulted from traffic flow dynamics such as traffic state transition. Therefore in this study an adaptive control method based on the artificial neural‐network theory is proposed to be tailored to the traffic state transition. The model is based on aerodynamic equations and takes vehicle speed and density as main system disturbances, whose value can be determined by fundamental diagram when having incomplete field traffic data. The proposed controller can also cope with the parameters and uncertainties of the time‐varying model. The authors simulation results show that the adaptive control method can track the desirable system output effectively whenever the traffic condition changes gently or dramatically. The results also show that their method performs better than the common‐used proportional integral derivative controller in terms of system adaptability following the traffic state transition.
X‐band SiGe bi‐complementary metal–oxide semiconductor transmit/receive module core chip for phased array RADAR applications
Authors: Dinc Tolga , Özeren Emre , Çalışkan Can , Kayahan Hüseyin , Gurbuz Yasar
Published: March 2015

This study presents a transmit/receive (T/R) module core chip with 4‐bit operation using 0.25 µm silicon–germanium (SiGe) bi‐complementary metal–oxide semiconductor (BiCMOS) technology, for X‐band phased array RADAR applications. The T/R module core chip consists of sub‐blocks such as low noise amplifier, power amplifier, phase shifter, single‐pole double‐throw switch and variable gain amplifier. Switches incorporate n‐type MOS devices while amplifiers are implemented with SiGe heterojunction bipolar transistors. Measurement results for the complete core chip and its individual sub‐blocks are reported here. Between 9 and 10 GHz, the constructed T/R module achieves about 11 dB gain for both receiver (RX) and transmitter (TX) chains, while it has −10.5 dBm receiver chain third‐order intermodulation intercept point (IIP3), and 16 dBm OP1 dB for transmitter chain. Root‐mean‐square phase error is measured as 5, whereas noise figure varies between 4 and 6 dB. The total power dissipation of core chip is about 285 mW, with a total area of 4.9 mm2.
Minimisation of thermally induced microbending losses in dual‐coated optical fibres caused by viscoelastic behaviour of commercial polymeric coatings
Authors: Hsueh Yu‐Chun , Chiou Sheng‐Che , Shiue Sham‐Tsong
Published: March 2015

The viscoelastic behaviour of commercial polymeric coatings for optical fibres is measured at room temperature using dynamic mechanic analysis, and the relationship between strain and stress in polymeric coatings is obtained. The thermally induced viscoelastic stresses in dual‐coated optical fibres are derived from the viscoelastic behaviour of commercial polymeric coatings. The compressive radial stress on the glass fibre surface produces microbending losses, which can be diminished by properly choosing the thickness and material properties of polymeric coatings. The design of dual‐coated optical fibres to diminish thermally induced microbending losses caused by viscoelastic behaviour of polymeric coatings is proposed. The thermally induced microbending loss in dual‐coated optical fibres evaluated by Maxwell model is underestimated.
Indirect sliding mode power control for three phase grid connected power converter
Authors: Hemdani Asma , Dagbagi Mohamed , Naouar Wissem Mohamed , Idkhajine Lahoucine , Slama Belkhodja Ilhem , Monmasson Eric
Published: March 2015

Grid connected power converters are widely used to interface between grid – on one side‐ and loads or renewable energy sources – on the other side. This work presents an indirect sliding mode power control (ISMPC) for three phase grid connected power converter. This control is characterised by improved robustness with regard to external disturbances and parameters changes, while insuring at the same time low current total harmonic distortion factor. The development and implementation of the ISMPC algorithm on low cost Microsemi SmartFusion digital solution is also described. This digital solution includes in the same chip a Field Programmable Gate Array (FPGA) fabric and a Cortex‐M3 processor associated to large number of peripheral cores. The developed ISMPC is compared with standard and commonly used controls for grid connected converters to show its interest and advantages. Moreover, an overview of the experimental set‐up, the description of the algorithm modular partitioning between FPGA and processor, the resources optimisation as well as the execution time reduction are presented. Selected experimental results corresponding to different operation steps are presented to illustrate performances and effectiveness of the proposed ISMPC algorithm.
Operational characteristics of hybrid‐powered three‐phase induction motor via synchronous and photovoltaic generators with MPPT utilised by synchronous generator automatic voltage regulator
Authors: Widyan Mohammad S.
Published: March 2015

The operational characteristics of a stand‐alone hybrid‐powered system are investigated. The sources are conventionally powered synchronous generator and photovoltaic (PV) array. The voltage of the common coupling point is controlled by the automatic voltage regulator of the synchronous generator via which the maximum power point (MPP) of the PV generator is tracked using the open‐circuit voltage method. Numerical simulations based on the non‐linear dynamical model in dq stationary reference frame are conducted. Power control unit is incorporated to control the driving torque of the synchronous generator once the PV generator becomes unable to meet the requirements of the motor because of reduction of the solar irradiance and/or increase of the load. The analysis includes the response of the system after step changes in the load coupled to the motor and after step changes in the levels of the solar irradiance. The steady‐state characteristics of the induction motor in case of hybridisation at various solar intensities are presented and compared with the case when the motor is powered by fixed terminal voltage. It is concluded that the proposed system can run at wide range of operating conditions and robust enough to withstand system parameters step changes.
Real‐time imbalance compensator for wideband receiver applications
Authors: Mancuso Vincent , Buxa Peter , Cheng Chi‐Hao , Lin David , Liou Lihyeh , Longbrake Matthew , Pemberton Thomas
Published: March 2015

To increase the bandwidth of a wideband receiver for surveillance applications, an in‐phase/quadrature‐phase (I/Q) channel‐based receiver is a potential approach. However, the image caused by an imperfect coupler prevents the I/Q channel‐based receiver from becoming a reality. Air Force Research Laboratory developed an imbalance compensation method covering two Nyquist zones. In this study, the authors present its implementation with a field‐programmable gate array board. Experimental results demonstrate the effectiveness of the proposed imbalance compensation algorithm and its feasibility.
Variable slip‐frequency strategy for reducing non‐equal deviations output by paralleled single‐sided linear induction motors
Authors: Jiangming Deng , Tefang Chen , Jianxiang Tang , Chunyang Chen
Published: March 2015

A predictive variable slip‐frequency (PVSF) control strategy is presented to reduce non‐equal output thrust deviation even though the existence of primary imbalancing input current is allowed. Besides current and speed sensors, the proposed strategy takes no additional sensors for that it only employs the real‐time speed signal and the latest instantaneous slip‐frequency to generate the predictive dynamical slip‐frequency corresponding to deviation of thrust output by paralleled single‐sided linear induction motors (SLIMs) groups. Owing to its insensitive to primary current d/q axes components for the generation of variant slip‐frequency, the PVSF strategy owns a significant anti‐noise ability since as big inertia system, the speed of parallel SLIM groups cannot vary abruptly. Both simulations and experimental results verify the feasibility of the proposed PVSF strategy.
Vibration parameter estimation methods for ultrasonic measurement systems – a review
Authors: Singh Kshetrimayum Milan , Sumathi Parasuraman
Published: March 2015

A review of vibration signal estimation techniques employed in ultrasonic vibration measurement systems is presented. The review focuses on the Doppler signal extraction methods including the theory and analysis pertaining to the background of ultrasonic vibration measurement techniques. The phase modulated received signal in the vibration measurement system involves constant phase shift because of ultrasonic path length, phase shift introduced by Doppler effect because of vibrating object and the parametric phase shift caused by interaction of high frequency ultrasonic wave and low pressure developed by vibrating object. Among the three phase shifts, the Doppler phase shift contains the vibrating signal information and the extraction of Doppler signal helps in knowing the velocity of the vibrating object, amplitude and phase of the vibration. Various techniques of Doppler phase shift retrieval are categorised based on the modulation index estimation procedures from the received ultrasonic signal. An analysis is made based on the information retrieval methods for estimation of vibration signal parameters, range of the vibration amplitude, frequency and the preferable carrier frequency for transmission. Further, the analysis also presents various applications in which ultrasonic vibration measurements system are employed successfully.
Implementation of a light Flickermeter in a low cost embedded system
Authors: Colnago Guilherme Piazentini , Macedo Jose Rubens , Vieira Jose Luiz de Freitas
Published: March 2015

This study presents the development and implementation of an alternative Flickermeter based on a low cost embedded electronic system. The development of this new device is based on the original Flickermeter proposed by the IEC 61000‐4‐15, but with important modifications added. These modifications allow for direct quantification of light variation, in such a way, so as to eliminate the effect associated with the different lamp technologies available through the correct quantification of flicker severity. In order to achieve this objective blocks 1 and 3 of the original IEC Flickermeter were altered and block 2 was completely eliminated. The implementation of a low cost embedded electronic system represents the differential of the developed system in relation to equipment currently available on the market, which is based on solutions of a more elevated cost. The developed prototype was appropriately tested and thus provided encouraging results. In addition, the article also presents an analysis that refers to the susceptibility of lamps manufactured upon the same technologies to flicker, such as compact fluorescent and LED lamps, widely used nowadays for substituting traditional incandescent lamps.
Use of electric field orientation as an index for estimating the contribution of model complexity in transcranial direct current stimulation forward head model development
Authors: Shahid Syed Salman , Song Bo , Salman Humaira , de Oliveira Marilia Menezes , Wen Peng
Published: March 2015

The study evaluates the role of human skull composition and brain anisotropy in the context of transcranial direct current stimulation (tDCS) based predictive modeling. Four head models were developed and each proposed attribute (cancellous bone and brain anisotropy) was compared with the isotropic model. By employing a single high‐definition montage, the efficacy of each attribute in shaping induced electric field was analyzed by its magnitude and orientation information. Relative error (RE) was used to estimate the variation in field magnitude. It was observed that for a given high‐definition montage, the brain anisotropy contributed to 5% change (RE) in the strength of the gray matter (GM) electric field and 10% for the white matter (WM). Inclusion of diploe in the model resulted in 45% variation in the magnitude of the brain electric field. On average, brain anisotropy contributed to field deviations of up to 20 degrees in major WM fiber tracts. Skull heterogeneity caused field deviations of up to 35 degrees in diploe, 15 degrees in subcutaneous fat and marginal variations in brain regions. These simulation results demonstrated the importance of considering refinement in forward models of tDCS, especially; the role of diploe should be considered for more accurate field assessments.
Modelling of aged cavities for partial discharge in power cable insulation
Authors: Shahsavarian Tohid , Shahrtash Seyyed Mohammad
Published: March 2015

In this study, the ageing process of cavities in solid insulation of power cables is divided into three stages, and for each stage a circuit model is proposed. Each of these circuit models preserves the basic characteristics of the cavity under the circumstances of the corresponding stage and provides the expected behaviour of generated partial discharge (PD) pulses. This set of models simulate cavity wall effects, the non‐uniformity of internal electrical field and charge deployed on the wall surfaces with considering the existence of electronegative gases according to the requirements of the three defined ageing stages. Finally, the simulation results, in the forms of phase resolved PD patterns are presented showing good agreement with the published experimental measurements drawn from accelerated ageing process setups.
Comparisons of three modelling methods for the forward problem in three‐dimensional electrical capacitance tomography
Authors: Yan Hua , Sun Yan Hui , Wang Yi Fan , Zhou Ying Gang
Published: March 2015

Image reconstruction of electrical capacitance tomography (ECT) belongs to solving an inverse problem. The first step to solve the inverse problem is to establish a forward problem model which determines the capacitance values for known permittivity distribution. There are three main methods for ECT forward problem modelling. The first is based on the sensitivity definition. The second is based on the multiple linear regression (MLR) method. And the third is based on the electric field strength (EFS). In this study, comparisons of these three modelling methods for the forward problem in three‐dimensional ECT are given in terms of modelling error, computational time and reconstruction quality. Comparison results show that the MLR method generates smallest modelling error and better reconstruction quality, especially for the very complex geometry with objects in the shape of letters H and U. However, the EFS method is significantly better than the other two methods in computational time.