bluuebunny/crossref_metadata_2025 huggingface dataset:
The Profitability of Sustainable Agriculture on a Representative Grain Farm in the Mid-Atlantic Region, 1981–89
Authors: Hanson James C. , Johnson Dale M. , Peters Steven E. , Janke Rhonda R.
Published: May 2019

A long-term whole-farm analysis compared conventional and low-input farming systems. Data from a nine-year agronomic study at the Rodale Research Farm, Kutztown, Pennsylvania, were used to analyze profitability, liquidity, solvency, and risk on a representative commercial grain farm. Conventional and low-input farms participating in government programs are the most profitable scenarios, followed by conventional and low-input farms not participating in government programs. All farms increased their net worth. The low-input approach is advantageous for risk-averse farmers using a safety-first criterion.
Conjoint Analysis of Deer Hunting
Authors: Mackenzie John
Published: May 2019

This paper develops a logit-based conjoint analysis of willingness to pay for individual attributes of deer-hunting trips. Since deer-hunting success is uncertain, willingness to pay for enhanced likelihood of bagging a deer, rather than for certain success, is evaluated. Implicit costs of recreational travel time are also evaluated from hypothetical trade-offs between travel time and trip expenditures. The valuation of travel time derived here appears to reflect more the opportunity cost of foregone hunting than the opportunity cost of foregone work. This implies that travel-cost analyses of recreational demand, which impute costs of recreational travel solely from wage data, can yield biased valuations of recreational amenities.
Assessing Morphological Development Within Special Education Settings
Authors: Bowey Judith A. , Mathews Dolour M.
Published: May 2019

This study was designed both to evaluate the Biks and Gutches test as a measure of morphological development in children within special education settings, and to determine whether or not these children have acquired a generative morphology. Two groups of children were pretested on the Biks and Gutches test. An experimental group received a short teaching program designed to familiarize them with concepts underlying the Berko procedure. Both the experimental and the control group were then retested on the Biks and Gutches test. The teaching program enhanced performance, indicating that this test might in part reflect abilities other than morphological development. Children experienced greater difficulty with nonsense word than with real word items. However, performance on comparable real word and nonsense word items was strongly correlated, indicating that these children have acquired a generative morphology.
Mastery Learning: The Achievement of Excellence
Authors: Hallinan Peter
Published: May 2019

This paper examines and critically evaluates the concept of mastery learning, ranging from its early development by such writers as Bloom and Keller, through to its various applications from preschool to tertiary levels of education, concluding with some speculation about future developments.
Developing a Project to Improve Employability for Secondary Students with Special Education Needs
Authors: Roberts-Yates Christine
Published: May 2019

Note: This article provides the theoretical background for the Social Skills and Employability Project in South Australia. The Project was established in 1989 by the S.A. Education Department (Northern Area) and the Institute for the Study of Learning Difficulties. It is a school and industry based project designed to develop personal, social, and vocational skills for young people with special educational needs. The author has agreed to write a further article describing the program in action. This will appear in a future issue of the journal.
Effective Questioning in the Classroom
Authors: Webb Rosalind , McCandlish Susan
Published: May 2019

The ability to question students effectively is, without doubt, one of a teachers most valuable assets. Through questions students can be led to make discoveries about the world, and to pose and solve their own problems. It must be recognised, however, that children may need tobe taught how to respond to different tyres of questions, and how to use questions to elicit the information they want. Despite the possibility that questioning can be overused (Wood, Wood, Griffiths, & Howarth, 1986), and the accusation that it can reduce the quality of conversational interchanges in the dassroom (Tizard & Hughes, 1984), the ability to question and respond to questions remain as important classroom behaviours: “Teachers and studerts who learn to comprehend the functions of the various types of questions can be expected to have more control over their enquiry” (Mann-Mandlebaurn, 1990).
Noble Gas and Carbon Isotope Systematics at the Seemingly Inactive Ciomadul Volcano (Eastern‐Central Europe, Romania): Evidence for Volcanic Degassing
Authors: Kis B. M. , Caracausi A. , Palcsu L. , Baciu C. , Ionescu A. , Futó I. , Sciarra A. , Harangi Sz.
Published: May 2019

Ciomadul is the youngest volcano in the Carpathian‐Pannonian Region, Eastern‐Central Europe, which last erupted 30 ka. This volcano is considered to be inactive, however, combined evidence from petrologic and magnetotelluric data, as well as seismic tomography studies, suggests the existence of a subvolcanic crystal mush with variable melt content. The volcanic area is characterized by high CO2 gas output rate, with a minimum of 8.7 × 103 t/year. We investigated 31 gas emissions at Ciomadul to constrain the origin of the volatiles. The δ13C–CO2 and 3He/4He compositions suggest the outgassing of a significant component of mantle‐derived fluids. The He isotope signature in the outgassing fluids (up to 3.10 Ra) is lower than the values in the peridotite xenoliths of the nearby alkaline basalt volcanic field (R/Ra 5.95 Ra ± 0.01), which are representative of a continental lithospheric mantle and significantly lower than MORB values. Considering the chemical characteristics of the Ciomadul dacite, including trace element and Sr–Nd and O isotope compositions, an upper crustal contamination is less probable, whereas the primary magmas could have been derived from an enriched mantle source. The low He isotopic ratios could indicate a strongly metasomatized mantle lithosphere. This could be due to infiltration of subduction‐related fluids and postmetasomatic ingrowth of radiogenic He. The metasomatic fluids are inferred to have contained subducted carbonate material resulting in a heavier carbon isotope composition (δ13C is in the range of −1.4‰ to −4.6‰) and an increase of CO2/3He ratio. Our study shows the magmatic contribution to the emitted gases.
The Influence of Substorms on Extreme Rates of Change of the Surface Horizontal Magnetic Field in the United Kingdom
Authors: Freeman Mervyn P. , Forsyth Colin , Rae I. Jonathan
Published: May 2019

We investigate how statistical properties of the rate of change R of the surface horizontal magnetic field in the United Kingdom differ during substorm expansion and recovery phases compared with other times. R is calculated from 1‐min magnetic field data from three INTERMAGNET observatories—Lerwick, Eskdalemuir, and Hartland and between 1996 and 2014—nearly two solar cycles. Substorm expansion and recovery phases are identified from the SuperMAG Lower index using the Substorm Onsets and Phases from Indices of the Electrojet method. The probability distribution of R is decomposed into categories of whether during substorm expansion and recovery phases, in enhanced convection intervals, or at other times. From this, we find that 54–56% of all extreme R values (defined as above the 99.97th percentile) occur during substorm expansion or recovery phases. By similarly decomposing the magnetic local time variation of the occurrence of large R values (>99th percentile), we deduce that 21–25% of large R during substorm expansion and recovery phases are attributable to the Disturbance Polar (DP)1 magnetic perturbation caused by the substorm current wedge. This corresponds to 10–14% of all large R in the entire data set. These results, together with asymptotic trends in occurrence probabilities, may indicate the two‐cell DP2 magnetic perturbation caused by magnetospheric convection as the dominant source of hazardous R > 600 nT/min that is potentially damaging to the U.K. National Grid. Thus, further research is needed to understand and model DP2, its mesoscale turbulent structure, and substorm feedbacks in order that GIC impact on the National Grid may be better understood and predicted.
Monitoring Haiti’s Quakes with Raspberry Shake
Authors: Calais Eric , Boisson Dominique , Symithe Steeve , Momplaisir Roberte , Pr�petit Claude , Ulysse Sophia , Etienne Guy , Courboulex Fran�oise , Deschamps Anne , Monfret Tony , Ampuero Jean-Paul , de L�pinay Bernard , Clouard Val�rie , Bossu R�my , Fallou Laure , Bertrand Etienne
Published: May 2019

A network of “personal seismometers” is intended to complement Haiti’s national seismic network to engage and inform residents about earthquake hazards and preparation.
Leaping Global Temperatures Make Frog Disease Deadlier
Authors: Cartier Kimberly
Published: May 2019

Climate change will shift the warmest months, when disease rates spike, into tadpole season, which could endanger the long-term survival of common frogs.
Deciphering Color Reflectance Data of a 520‐kyr Sediment Core From the Southern Ocean: Method Application and Paleoenvironmental Implications
Authors: Wu Li , Wang Rujian , Krijgsman Wout , Chen Zhihua , Xiao Wenshen , Ge Shulan , Wu Jiawang
Published: May 2019

Sediment color reflectance contains important information on paleoenvironmental changes. Such data are routinely measured on sediment cores from the Southern Ocean. Their usefulness, however, is undervalued. Here for the first time, color reflectance of an ~520‐kyr sediment core retrieved off Prydz Bay (East Antarctica) was intensively investigated to correlate sediment color changes to changes in sediment compositions. Total carbon, total organic carbon, X‐ray fluorescence‐derived Fe/Ti and Br/Ti ratios, water content and mineral composition of sediment from this core, and color reflectance of another two sediment cores retrieved nearby were analyzed in this study. The raw reflectance data were transformed into their first‐order derivatives and subjected to factor analysis algorithms. A four‐factor model was selected to unmix the data set, explaining >80% of the total data variance. Its robustness is supported by similar factor analysis results from the other two cores. The four factors represent (from Factors 1–4) pulses of sedimentary Mn enrichment and Fe3+/Fe2+ changes in clay minerals, relative content changes of colorless components, hematite and goethite, and water, respectively. Scores of Factor 1 show high spikes at glacial terminations, recording enhanced deglacial ventilation in the abyssal Southern Ocean. Scores of Factor 2 mainly reflect biogenic components and chlorite but are further complicated by refractory terrigenous organic carbon and Mn‐oxides/‐hydroxides. Higher Scores of Factor 3 occur mainly at peak interglacial intervals, associated with enhanced transport of sediment of Antarctic origin by oceanic currents. Water content (Factor 4) in the core sediment was significantly influenced by opal content and sediment grain size compositions.
The Budget of Macrobenthic Reworked Organic Carbon: A Modeling Case Study of the North Sea
Authors: Zhang Wenyan , Wirtz Kai , Daewel Ute , Wrede Alexa , Kröncke Ingrid , Kuhn Gerhard , Neumann Andreas , Meyer Julia , Ma Mengyao , Schrum Corinna
Published: May 2019

The importance of macrobenthos in benthic‐pelagic coupling and early diagenesis of organic carbon has long been recognized but has not been quantified at a regional scale. By using the southern North Sea as an exemplary area we present a modeling attempt to quantify the budget of total organic carbon (TOC) reworked by macrobenthos in seafloor surface sediments. Vertical profiles in sediments collected in the field indicate a significant but nonlinear correlation between TOC and macrobenthic biomass. A mechanistic model is used to resolve the bidirectional interaction between TOC and macrobenthos. A novelty of this model is that bioturbation is resolved dynamically depending on variations in local food resource and macrobenthic biomass. The model is coupled to 3‐D hydrodynamic‐biogeochemical simulations to hindcast the mutual dependence between sedimentary TOC and macrobenthos from 1948 to 2015. Agreement with field data reveals a satisfactory model performance. Our simulations show that the preservation of TOC in the North Sea sediments is determined not only by pelagic conditions (hydrodynamic regime and primary production) but also by the vertical distribution of TOC, bioturbation intensity, and the vertical positioning of macrobenthos. Macrobenthos annually ingest 20–35% and in addition vertically diffuse 11–22% of the total budget of TOC in the uppermost 30‐cm sediments in the southern North Sea. This result indicates a central role of benthic animals in modulating the organic carbon cycling at the sediment‐water interface of continental margins.
Solar Radio Burst Events on 6 September 2017 and Its Impact on GNSS Signal Frequencies
Authors: Sato H. , Jakowski N. , Berdermann J. , Jiricka K. , Heßelbarth A. , Banyś D. , Wilken V.
Published: May 2019

During the intense solar radio bursts on 6 September 2017, Global Navigation Satellite Systems (GNSS) signal interferences were observed at ground stations in the European longitude sector from 20°N to 70°N for all GNSS satellites in view including GPS, GLONASS, and Galileo. The solar radio noise reduced the signal‐to‐noise ratio with clear frequency dependence. The impact of the radio burst has been found at L2 and L5 frequencies, but not at L1 frequency. The ground observation of the solar radio spectrum between 1.0 and 2.0 GHz corresponds well to such frequency dependence. The maximum signal‐to‐noise ratio reduction of ‐10 dB was found when the solar radio flux was pulsating around 2,000 solar flux unit level. Precise point positioning results show that accuracy is reduced with stronger deviation for dual‐frequency solutions than for single‐frequency solutions based on L1 signal only. The positioning error refers rather to the solar extreme ultraviolet flare than to solar radio interferences. The results presented here are a clear indication of frequency‐dependent GNSS performance degradation during strong space weather events.
MOF-derived Co1.11Te2 with half-metallic character for efficient photochemical conversion of CO2 under visible-light irradiation
Authors: Xu Yong , Mo Jiang , Xie Guanqun , Ding Dawei , Ding Shujiang , Wang Xiaoxia , Li Chen
Published: May 2019

Co1.11Te2 enwrapped in a carbon layer displayed high catalytic performance for photocatalytic CO2 reduction. The strong electron transfer ability and the low energy barrier are the key factors that promote its high catalytic activity.
Effect of surfactants on the molecular mobility and crystallization kinetics of hesperetin
Authors: Sheokand Sneha , Sharma Jagadish , Bansal Arvind K.
Published: May 2019

Recent work from our lab studied the generation and performance evaluation of nanocrystalline solid dispersions (NCSDs) of a hesperetin-mannitol-sodium lauryl sulphate (SLS)-dioctyl sodium sulphosuccinate (DOSS) system.
Bidentate Ru(ii)-NC complexes as catalysts for the dehydrogenative reaction from primary alcohols to carboxylic acids
Authors: Gong Dawei , Hu Bowen , Chen Dafa
Published: May 2019

Complex1is active for alcohol dehydrogenative reactions, and two critical intermediates were isolated and characterized.
Constructing a novel family of halogen-doped covalent triazine-based frameworks as efficient metal-free photocatalysts for hydrogen production
Authors: Cheng Zhi , Zheng Kaiyun , Lin Guiyun , Fang Shengqiong , Li Liuyi , Bi Jinhong , Shen Jinni , Wu Ling
Published: May 2019

Developing metal-free halogen-doped covalent triazine-based frameworks for enhanced visible-light-driven photocatalytic H2-production performances.
Cost-effective dopant-free star-shaped oligo-aryl amines for high performance perovskite solar cells
Authors: Feng Jun-Ying , Lai Kuan-Wen , Shiue Yuan-Shin , Singh Ashutosh , Kumar CH. Pavan , Li Chun-Ting , Wu Wen-Ti , Lin Jiann T. , Chu Chih-Wei , Chang Chien-Cheng , Su Chao-chin
Published: May 2019

Cost-effective imidazole-based star-shaped arylamines were used as dopant-free hole transport materials (HTMs) for high performance perovskite solar cells (17.47%).
Engineering the underlying surface to manipulate the growth of 2D perovskites for highly efficient solar cells
Authors: Tian Shuoxun , Chen Jiehuan , Lian Xiaomei , Wang Yaqin , Zhang Yingzhu , Yang Weitao , Wu Gang , Qiu Weiming , Chen Hongzheng
Published: May 2019

High efficiency (12.78%) 2D perovskite solar cells are realized by engineering the substrate to manipulate the growth of 2D perovskites.
Study on pairwise LDA for x‐vector‐based speaker recognition
Authors: Kanagasundaram A. , Sridharan S. , Ganapathy S. , Fookes C.
Published: May 2019

In typical x‐vector‐based speaker recognition systems, standard linear discriminant analysis (LDA) is used to transform the x‐vector space with the aim of maximising the between‐speaker discriminant information while minimising the within‐speaker variability. For LDA, it is customary to use all the available speakers in the speaker recognition development dataset. In this study, the authors investigate if it would be more beneficial to estimate the between‐speaker discriminant information and the within‐speaker variability using the most confusing samples and the most distant samples (from the target speaker mean), respectively, in the LDA‐based channel compensation. The between‐speaker variance is estimated using a pairwise approach where the most confusing non‐target speaker samples are found based on the Euclidean distance between the speaker mean and adjacent speaker's samples. The within‐speaker variance is estimated using the mean of each speaker and the furthermost samples in the speaker sessions. Experimental results demonstrate the proposed LDA approach for an x‐vector‐based speaker recognition system achieves over 17% relative improvement on equal error rate over standard LDA‐based x‐vector speaker recognition systems on the NIST2010 corext–corext condition.
Real‐time target object tracking via dual‐directional scaling state predicting
Authors: Liu Tong , Cao Xiaochun , Jiang Jianmin
Published: May 2019

Visual tracking using correlation filters can achieve a high running speed. However, it is still a challenging problem to deal with drastic appearance changes (e.g. large and rapid scale variation of a target) during tracking. In this Letter, a novel dual‐directional scaling state predicting method based on correlation filtering is proposed. The adaptive horizontal and vertical searches are adopted to separately and accurately estimate the scale changes in different directions. The online scale to size module is designed to enhance the prediction robustness of the target appearance. Experimental comparisons with several state‐of‐the‐art object trackers show the effectiveness and efficiency of the proposed approach.
TEnet: target speaker extraction network with accumulated speaker embedding for automatic speech recognition
Authors: Li Wenjie , Zhang Pengyuan , Yan Yonghong
Published: May 2019

It is challenging to perform automatic speech recognition when multiple people talk simultaneously. To solve this problem, speaker‐aware selective methods have been proposed to extract the speech of the target speaker, relying on the auxiliary speaker characteristics provided by an anchor (a clean audio sample of the target speaker). However, the extraction performance depends on the duration and quality of the anchors, which is unstable. To address this limitation, the authors propose a target speaker extraction network (TEnet) which applies the robust speaker embedding to extract the target speech from the speech mixture. To get more stable speaker characteristics during training, the robust speaker embeddings are accumulated over all the speech of each target speaker, rather than utilising the embedding produced by a single anchor. As for testing, very few anchors are enough to get decent extraction performance. Results show the TEnet trained with accumulated embedding achieves better performance and robustness compared with the single‐anchored TEnet. Moreover, to exploit the potential of the speaker embedding, the authors propose to feed the extracted target speech as anchor and train a feedback TEnet, whose results are superior to the short‐anchored baseline for 22.5% on word error rate and 15.5% on signal‐to‐distortion rate.
Low‐complexity carrier frequency offset estimation for UFMC systems
Authors: Chen T.C. , Lin T.T.
Published: May 2019

In this Letter, the authors propose a simple carrier frequency offset estimation for universal filtered multicarrier (UFMC) systems, which not only greatly reduces the computational complexity but also promises excellent performance. First, based on the concept of the bisection method, a low‐complexity selection criterion is designed to iteratively narrow the frequency range of interest. Then, the carrier frequency offset is effectively estimated using a closed‐form expression derived from the Taylor series expansion technique. Computer simulations indicate that the proposed scheme can achieve performance comparable to the least squares‐based estimator using high‐complexity exhaustive search.
Design and evaluation of an alternative wheelchair control system for dexterity disabilities
Authors: Oliver Samuel , Khan Asiya
Published: May 2019

This work details the design and development of a novel 3D printed, modular alternative wheelchair control system for powered wheelchair users afflicted with dexterity inhibiting disorders, which mechanically interfaces directly with the installed standard joystick. The proposed joystick manipulator utilises an accelerometer for gesture control input processed by the Arduino microprocessor and a mechanical control interface, which sits over a standard installed two‐axis proportional joystick, the preferential control system for most powered chair manufacturers. When fitted, this allows powered electric wheelchair users with limited dexterity, independent to navigate their wheelchair unassisted. The mechanical system has been selected so that the joystick manipulator is as universal as possible and can be installed to almost any powered wheelchair that uses a two‐axis joystick. The design process and key aspects of the operation of the joystick manipulator are presented as well as field testing on a wheelchair conducted. The test results show that the proposed joystick manipulator is a successful system that can be universally fitted to most powered chairs and offers potentially greater independence for the powered wheelchair user.
Machine learning approach of automatic identification and counting of blood cells
Authors: Alam Mohammad Mahmudul , Islam Mohammad Tariqul
Published: May 2019

A complete blood cell count is an important test in medical diagnosis to evaluate overall health condition. Traditionally blood cells are counted manually using haemocytometer along with other laboratory equipment's and chemical compounds, which is a time‐consuming and tedious task. In this work, the authors present a machine learning approach for automatic identification and counting of three types of blood cells using ‘you only look once’ (YOLO) object detection and classification algorithm. YOLO framework has been trained with a modified configuration BCCD Dataset of blood smear images to automatically identify and count red blood cells, white blood cells, and platelets. Moreover, this study with other convolutional neural network architectures considering architecture complexity, reported accuracy, and running time with this framework and compare the accuracy of the models for blood cells detection. They also tested the trained model on smear images from a different dataset and found that the learned models are generalised. Overall the computer‐aided system of detection and counting enables us to count blood cells from smear images in less than a second, which is useful for practical applications.
Positive L1 ‐filter design for continuous‐time positive Markov jump linear systems: full‐order and reduced‐order
Authors: Chen Ying , Bo Yuming , Du Baozhu
Published: May 2019

This study addresses the positive filter design problem for continuous‐time positive Markov jump linear systems (PMJLSs). Based on the necessary and sufficient condition for ‐gain performance, two sufficient conditions to design positive full‐order and reduced‐order ‐filters for PMJLSs are provided in terms of linear programming, respectively. A practical numerical example of an isotropic, homogeneous and unidimensional aquifer is presented at last to show the effectiveness of the proposed schemes.
Experimental behaviour analysis for optimally controlled standalone DFIG system
Authors: Soued Salah , Chabani Mohammed Saci , Becherif Mohamed , Benchouia Mouhamed Toufik , Ramadan Haitham Saad , Betka Achour , Golea Amar , Zouzou Salah Eddine
Published: May 2019

Metaheuristic optimisation techniques such as the Grey Wolf optimiser (GWO) and artificial bee colony (ABC) algorithms have been developed for enhancing the dynamic behaviour of wind energy conversion system. The stand‐alone doubly fed induction generator (DFIG) control system based on the direct voltage control is experimentally validated for the robust independent control of the stator voltage amplitude and the consequent rotor current regulation. The GWO and ABC are used for selecting the optimal gains of the proportional–integral (PI) regulator to improve the dynamic performance and the robust stability of the DFIG system in the presence of step voltage variation and sudden load operation. Through, MATLAB™/Simulink numerical simulations, the dynamic performances of the GWO‐PI and ABC‐PI applied to stand‐alone DFIG systems are compared with the conventional PI controller under different disturbances. Using a 3 kW DFIG test bench DSPACE DS1104 card prototype, the experimental validation justifies the superiority of proposed novel GWO‐PI and ABC‐PI controllers over the conventional PI control in terms of steady‐state errors, maximum overshoots, settling time and rise time.
Multiple sampling PSC‐PWM with hierarchical control architecture for MMC‐DSTATCOM
Authors: Zhang Yuxiao , Dai Ke , Xu Chen , Kang Yong , Dai Ziwei
Published: May 2019

The modular multilevel converter (MMC) is attractive for medium‐ and high‐power applications because of its high modularity, availability and power quality. In this study, a quadruple sampling phase‐shifted‐carrier pulse‐width modulation (PSC‐PWM) strategy based on hierarchical distributed control architecture for MMC in medium‐voltage power distribution static synchronous compensator (DSTATCOM) application is presented. Compared to centralised control architecture, the multi‐digital signal processors master–slave hierarchical control architecture can enhance the scalability of MMC‐DSTATCOM and the sub‐module (SM) number can expand without limitation. To take advantage of the proposed hierarchical architecture, the multiple sampling PSC‐PWM technique is employed to improve the converter performance. The spectrum of the electromotive force of MMC with quadruple sampling is almost the same as that of natural sampling, which leads to fewer harmonics in reactive and harmonic current compensating. Besides, it also raises the sampling frequency so that the MMC‐DSTATCOM can compensate harmonic at the low SM switching frequency. The effectivenesses of the proposed architecture and modulation method are verified by experimental results obtained from a 60 V/2 kVA downscaled prototype.
Dynamic state estimation of power systems using intelligent particle filtering based on ant colony optimisation for continuous domains
Authors: Afrasiabi Shahabodin , Saffarian Alireza , Mashhour Elaheh
Published: May 2019

In this study, a dynamic state estimation (DSE) approach is proposed for power systems based on particle filter (PF) and ant colony optimisation for continuous domains (ACOR). Usually, the Kalman‐based estimators with Gaussian noise assumption are utilised for DSE. However, this assumption is questionable for real power system data. Although PF methods offer a potential solution for this issue, the basic PF algorithm is time‐consuming and suffers from sample impoverishment problem and degeneracy of the propagated samples. In this study, the search capability of ACOR is utilised as an adaptive probability density function estimator to overcome these shortcomings and reduce the required particle numbers. The proposed approach minimises the computational effort by reducing the required particle numbers. The ninth‐order model of the synchronous generator has been applied in this study. The performance of the proposed method is investigated through a two‐area‐four‐machine test system as well as the IEEE 39‐bus (New England) test system and it is compared with several advanced Kalman filter‐based and PF‐based approaches. The simulation results obtained for different case studies demonstrate the effectiveness and robustness of the proposed method against noises, abrupt state changes, and gross measurement errors.
Decentralised primary and secondary control strategies for islanded microgrids considering energy storage systems characteristics
Authors: Khodadoost Arani Ali Asghar , Gharehpetian Gevork B. , Abedi Mehrdad
Published: May 2019

One of the main subjects of Microgrid (MG) islanded operation is its stability. Using the Energy Storage Systems (ESSs) in MGs, the stability can be improved. To ensure the proper operation of the ESSs, their State of Charge (SoC) should be monitored and controlled. In this paper, a new decentralized control method based on the conventional droop method is proposed which considers different types of ESSs used in islanded MG, i.e. ESSs with high power density and high energy density. In the proposed method, the ESS units are divided into two main categories. The master ESS is the main primary frequency control unit and the other ESSs respond to active and reactive power variations of the load and participate in the secondary control of frequency. For each of these categories, a new control method is proposed. The proposed method, including the primary and secondary control, is decentralized, and based on local measurements. Moreover, in the proposed method, a SoC equalization of ESSs is considered. To assess the stability of the MG, a small signal stability model is developed. Three scenarios are simulated to verify the effectiveness of the proposed method in MG frequency control and ESSs SoC balancing.
SVM‐based hybrid approach for corridor‐level travel‐time estimation
Authors: Sharmila R.B. , Velaga Nagendra R. , Kumar Akhilesh
Published: May 2019

The objective of this study is to develop an accurate model for corridor‐level travel‐time estimation. Different approaches, such as k‐nearest neighbour (k‐NN), gradient boosting decision tree (GBDT) and support vector machines (SVMs), were used in this study. Further, this study also developed a hybrid model combining a data‐driven approach (SVM) and a model‐based approach [particle filter (PF)] for corridor‐level travel‐time estimation. Both static and dynamic parameters, such as road geometry, intersection length, location information from Global Positioning System devices, dwell time etc. were used as influential factors for modelling. The proposed algorithm was tested on a study corridor of length 59.48 km, in the arterials of Mumbai, India. The data was collected using a probe‐vehicle technique for five days during the morning peak period (from 8.00 am to 11.00 am) for two modes (car and bus). The mean absolute percentage error values obtained for the hybrid model for the two modes were: 9.96 (car) and 11.24 (bus). The performance of the proposed hybrid (SVM‐PF) algorithm showed a clear improvement in accuracy in comparison to existing standard methods such as k‐NN, GBDT and SVM.
Vision‐based traffic accident detection using sparse spatio‐temporal features and weighted extreme learning machine
Authors: Yu Yuanlong , Xu Miaoxing , Gu Jason
Published: May 2019

Vision‐based traffic accident detection is one of the challenging tasks in intelligent transportation systems due to the multi‐modalities of traffic accidents. The first challenging issue is about how to learn robust and discriminative spatio‐temporal feature representations. Since few training samples of traffic accidents can be collected, sparse coding techniques can be used for small data case. However, most sparse coding algorithms which use norm regularisation may not achieve enough sparsity. The second challenging issue is about the sample imbalance between traffic accidents and normal traffic such that detector would like to favour normal traffic. This study proposes a traffic accident detection method, including a self‐tuning iterative hard thresholding (ST‐IHT) algorithm for learning sparse spatio‐temporal features and a weighted extreme learning machine (W‐ELM) for detection. The ST‐IHT algorithm can improve the sparsity of encoded features by solving an norm regularisation. The W‐ELM can put more focus on traffic accident samples. Meanwhile, a two‐point search strategy is proposed to adaptively find a candidate value of Lipschitz coefficients to improve the tuning precision. Experimental results in our collected dataset have shown that this proposed traffic accident detection algorithm outperforms other state‐of‐the‐art methods in terms of the feature's sparsity and detection performance.
Optimised power control and balance scheme for the output parallel dual‐active‐bridge DC‐DC converters in power electronic traction transformer
Authors: An Feng , Song Wensheng , Yang Kexin , Luo Shucong , Feng Xiaoyun
Published: May 2019

In order to achieve a comprehensive performance optimisation consisting of transmission power balance, high efficiency, and fast dynamic response for the output parallel dual‐active‐bridge (DAB) dc–dc converters in power electronic traction transformer, an optimised power control and balance scheme based on extended phase‐shift (OPCB‐EPS) control is proposed in this study. By combining current stress‐optimised calculation with EPS control, the current stress of converters can be reduced significantly and the efficiency can be further improved. In addition, the desired transmission power of DAB converters is estimated on‐line by introducing the virtual voltage component to enhance the dynamic response of the output voltage under the input voltage fluctuation and the load disturbance conditions. Meanwhile, the proposed OPCB‐EPS scheme can realise the transmission power balance over the whole power range. Finally, a scale‐down prototype of DAB dc–dc converters consisting of three cells is developed to compare the performance of the current stress optimised with dual phase‐shift (CSO‐DPS), current stress optimised with EPS and proposed OPCB‐EPS schemes. The comparative experimental results have verified the excellent performance of OPCB‐EPS scheme and the theoretical analysis in this work.
Single‐magnetic equaliser without any sensors for series‐connected battery strings
Authors: Liu Fulin , Zou Runmin , Su Mei , Sun Yao , Liu Yonglu , Li Xing , Wang Hui , Xu Guo
Published: May 2019

This study proposes an automatic cell‐to‐cell equaliser to balance the battery voltages in series‐connected battery strings. In the proposed equaliser, each cell needs only one MOSFET, and the adjacent cells share the transformer winding. The voltage balance is automatically realised by using a pair of complementary control signals with a fixed duty cycle. What's more, no sensing circuit is required. Consequently, the proposed equaliser is cost‐effective and easy‐to‐realise. The circuit topology and operating principles are firstly presented. Then the voltage balance analysis is given in detail. Moreover, a design guide is also given by considering four lithium‐ion cells. Finally, the validity of the proposed equaliser is verified by experimental results.
Performance comparison of CdTe thin film modules with c‐Si modules under low irradiance
Authors: Ahsan Syed M. , Khan Hassan A.
Published: May 2019

The efficiency of solar panels declines from its rated (standard testing conditions) value under low irradiance which typically occurs in the mornings, evenings and on cloudy days. In this work, the authors evaluate cadmium telluride (CdTe) thin film panels due to their increasing market share and assess their low irradiance performance in comparison with conventional crystalline‐Silicon (c‐Si) panels. The performance of both material systems is analysed for a 4‐year period to evaluate their performance in terms of their relative change in efficiency and energy yield. Further analysis on a high‐resolution 8‐day measured data for winters and summers shows that CdTe panels provide ∼1.09% higher specific energy yield compared to c‐Si panels. This primarily occurs due to higher CdTe bandgap and better spectral response at lower insolation levels resulting in an enhanced relative efficiency with respect to c‐Si panels.
Current controller design for DFIG‐based wind turbines using state feedback control
Authors: Abo‐Khalil Ahmed G. , Alghamdi Ali , Tlili I. , Eltamaly Ali M.
Published: May 2019

Doubly‐fed induction generators (DFIGs) are widely used in wind energy conversion systems. The dynamic features of DFIGs make it important to focus on designing high‐performance control schemes. However, the dynamic characteristics of such generators depend on nonlinear parameters, such as stator flux, stator current, and rotor current, which increase overall system complexity. Therefore, robust controllers must be implemented with the ability to support the dynamic frequencies of wind energy to ensure system stability. Conventional vector control configurations that use proportional‐integral controllers have various drawbacks, such as parameter tuning difficulties, mediocre dynamic performance, and reduced robustness. In this study, improving DFIG dynamics by applying a multivariable state feedback current controller with a feedforward component to improve the steady‐state and transient characteristics of the controller has been introduced and discussed. Multivariable state feedback controllers are proposed to replace the proportional‐integral controllers on both the rotor and grid sides. The proposed controller is designed using a multivariable system and feedforward control for input reference and incorporating disturbances into the control equations for fast transient responses. To demonstrate the advantages of this controller, experimental studies are presented for both the transient and steady states.
Modelling and analysis of an analogue MPPT‐based PV battery charging system utilising dc–dc boost converter
Authors: Shaw Priyabrata
Published: May 2019

Nowadays, the research is being devoted to the development of rapid and precise maximum power point tracking (MPPT) for various photovoltaic (PV) applications. However, the constraints imposed by size, cost, efficiency, and tracking performances essentially limit the application of conventional MPPT techniques and their analysis methodologies. This study recommends a fast and robust analogue PV MPPT for the battery charging system using dc–dc boost converter. The fast dynamic performances with absolute robustness are ensured here by fast‐scale stability analysis of actually switched boost converter using the concepts based on non‐linear dynamics and bifurcation theory. Such concepts not only provide the information to design an efficient MPPT system under rapidly changing environmental conditions but also guarantee the system to operate either in period‐1 or chaotic mode. The theoretical and mathematical analyses are experimentally verified using a prototype PV battery charging system utilising dc–dc boost converter. It is presented that operating the MPPT system in chaos not only yields the broader power spectrum with reduced spectral peaks at the multiples of converter's switching frequency but also exhibits high overall conversion efficiency.
Management of renewable‐based multi‐energy microgrids in the presence of electric vehicles
Authors: Shafie‐khah Miadreza , Vahid‐Ghavidel Morteza , Di Somma Marialaura , Graditi Giorgio , Siano Pierluigi , Catalão João P.S.
Published: May 2019

This study proposes a stochastic optimisation programming for scheduling a microgrid (MG) considering multiple energy devices and the uncertain nature of renewable energy resources and parking lot‐based electric vehicles (EVs). Both thermal and electrical features of the multi‐energy system are modelled by considering combined heat and power generation, thermal energy storage, and auxiliary boilers. Also, price‐based and incentive‐based demand response (DR) programs are modelled in the proposed multi‐energy MG to manage a commercial complex including hospital, supermarket, strip mall, hotel and offices. Moreover, a linearised AC power flow is utilised to model the distribution system, including EVs. The feasibility of the proposed model is studied on a system based on real data of a commercial complex, and the integration of DR and EVs with multiple energy devices in an MG is investigated. The numerical studies show the high impact of EVs on the operation of the multi‐energy MGs.
Performance analysis of different interference detection techniques for navigation with Indian constellation
Authors: Lineswala Priyanka L. , Shah Shweta N.
Published: May 2019

Navigation facilities are becoming a major part of every cutting‐edge application. However, interfering signals, such as jammer, are the primary concern for ensuring the reliability, accuracy, and integrity of each navigation application. This study focuses on the performance of different detection methods for software‐defined radio‐based class II jamming in the upcoming navigation with Indian constellation signals. The implementation and detection performance based on different receiver operating characteristic curves are analysed for well‐known methods such as power law detection, power spectral density, Kurtosis test, goodness‐of‐fit test with the introduction of Kolmogorov–Smirnov test.
Torque optimisation of seven‐phase BLDC machines in normal and degraded modes with constraints on current and voltage
Authors: Vu Duc Tan , Nguyen Ngac Ky , Semail Eric , dos Santos Moraes Tiago Jose
Published: May 2019

This study proposes several easy‐to‐implement control strategies when seven‐phase axial flux brushless DC machines with trapezoidal back electromotive forces operate in normal and faulty modes by taking into account constraints on voltage and current. The constraints are related to the converter and machine design in terms of maximum values of current and voltage. The considered faults are cases in which one or two phases of the machine are open‐circuited. Numerical computations based on analytical formulations are applied to obtain torque‐speed characteristics, including the flux‐weakening operation. The methods determine current references to ensure the torque optimisations while currents and voltages are within their limits. The usefulness of the methods is verified by numerical results.
Non‐linear MPC for winding loss optimised torque control of anisotropic PMSM
Authors: Schnurr Christoph , Hohmann Sören , Kolb Johannes
Published: May 2019

For a non‐linear anisotropic permanent magnet synchronous machine (PMSM), a prediction model for model predictive control (MPC) considering effects like cross‐coupling and saturation is developed in a straight forward procedure. The objective of the designed MPC is either tracking of reference currents or torque tracking. Both approaches use the projected fast gradient method (PFGM) as optimisation algorithm. The latter approach makes look‐up‐tables for current references obsolete and additionally minimises winding losses. This two approaches are compared in a simulation study with a state of the art PI controller.
Torque ripple reduction in homopolar poly‐phase transverse flux machine
Authors: Golatgaonkar Priyanka , Chaudhari Bhalchandra , Ugale Rajaram
Published: May 2019

The problem of high ripple in output torque is inherent to switched reluctance and permanent magnet machines compared to conventional machines. Torque ripple is undesirable as it leads to increased audible noise, speed ripple, and fatigue. Torque ripple is more prominent in complex machines like TFMs. This paper aims to tackle the problem of torque ripple in the homopolar poly‐phase transverse flux permanent magnet machine by machine design approach. Rotor pole shaping, increase in number of repetitions, and increase in number of phases have been considered to reduce torque ripple. The 3‐D finite element simulations have been carried out for the considered variations in geometry. Results of nature of air‐gap flux density at no‐load, cogging torque, average torque, and % ripple in the output torque are used to comment on the effectiveness of the torque ripple reduction techniques. The objective of this research is to reduce the torque ripple in the output torque to 10%. The technique/combination of techniques resulting in reduced torque ripple has been suggested to be implemented in the prototype.
Flap system power drive unit (PDU) architecture optimisation
Authors: Benarous Maamar , Panella Isabella
Published: May 2019

Conventional flap and slat high‐lift surfaces actuation systems in a commercial aircraft consist of actuators mechanically connected via a transmission system across the wingspan, driven from a centralised power drive unit comprising of a hydraulic, electric, or hybrid hydraulic/electric motor arrangement. The permanent coupling to the shafts makes the entire flap system move in unison, as do the slats. This paper will investigate and discuss different potential system architecture, and present the benefits associated with such architecture. It will also present the advantage that can be linked to a full electric flap configuration.
TC48: A low‐cost 48 V integrated drive for mild hybrid electric vehicles
Authors: Winterborne Dave , Shiref Muez , Snow Stuart , Pickert Volker
Published: May 2019

The TC48 drive is a low‐cost, low‐voltage integrated motor‐drive solution suitable for mild hybrid electric vehicles, off‐highway traction, and any application where a compact, highly torque‐dense machine is required. Low‐voltage solutions for electric vehicles are attractive to manufacturers due to lower insulation requirements, and hence lower cost. The package is based on a six‐phase switched reluctance machine, which uses a novel stator topology and unique winding design to achieve high torque density. The power electronics converter hardware is integrated into the motor housing, giving a physically, electrically, and thermally optimised solution. The complete package has been designed to be suitable for manufacturing in high volumes. This study describes the electromagnetic design of the motor, the mechanical innovations used to physically realise this design, and the cooling system which makes the high power density possible. The integration of the power electronics and their control is also discussed. The project is the result of collaboration between Newcastle and Loughbosrough Universities, RDM Ltd., Productiv, Infineon, Tata Steel, and Libralato.