bluuebunny/crossref_metadata_2025 huggingface dataset:
Hybrid Reverse Molecular Dynamics Simulation as New Approach to Determination of Carbon Nanostructure of Carbon Blacks
Authors: Ishida Masaya , Ohba Tomonori
Published: February 2020

Various carbon materials have been fabricated for use as catalyst supports, carriers, adsorbents, and electrodes as well as in other advanced applications. The performances of carbon materials in such applications can be improved by adjusting their physical properties, especially their nanostructures. The determination of the carbon nanostructure is thus considerably important. Reverse Monte Carlo and hybrid reverse Monte Carlo simulations, which are used to analyze the diffraction patterns of carbon materials, can be used to obtain nanostructure images. Here, we describe a new approach to carbon nanostructure investigation, namely, hybrid reverse molecular dynamics (HRMD) simulation. This approach has the advantage that all of the carbon atoms move toward probable carbon structures by force fields to adapt a simulated diffraction pattern to an experimental one, in contrast to the random movements in reverse Monte Carlo and hybrid reverse Monte Carlo simulations. HRMD simulation also prevents the formation of inappropriate structures.
Hypercholesterolemia Accelerates the Aging Phenotypes of Hematopoietic Stem Cells by a Tet1-Dependent Pathway
Authors: Tie Guodong , Yan Jinglian , Khair Lyne , Tutto Amanda , Messina Louis M.
Published: February 2020

Hypercholesterolemia accelerates the phenotypes of aging in hematopoietic stem cells (HSCs). As yet, little is known about the underlying mechanism. We found that hypercholesterolemia downregulates Ten eleven translocation 1 (Tet1) in HSCs. The total HSC population was increased, while the long-term (LT) population, side population and reconstitution capacity of HSCs were significantly decreased in Tet1−/− mice. Expression of the Tet1 catalytic domain in HSCs effectively restored the LT population and reconstitution capacity of HSCs isolated from Tet1−/− mice. While Tet1 deficiency upregulated the expression of p19 and p21 in HSCs by decreasing the H3K27me3 modification, the restoration of Tet1 activity reduced the expression of p19, p21 and p27 by restoring the H3K27me3 and H3K36me3 modifications on these genes. These results indicate that Tet1 plays a critical role in maintaining the quiescence and reconstitution capacity of HSCs and that hypercholesterolemia accelerates HSC aging phenotypes by decreasing Tet1 expression in HSCs.
Anak Krakatau triggers volcanic freezer in the upper troposphere
Authors: Prata A. T. , Folch A. , Prata A. J. , Biondi R. , Brenot H. , Cimarelli C. , Corradini S. , Lapierre J. , Costa A.
Published: February 2020

Volcanic activity occurring in tropical moist atmospheres can promote deep convection and trigger volcanic thunderstorms. These phenomena, however, are rarely observed to last continuously for more than a day and so insights into the dynamics, microphysics and electrification processes are limited. Here we present a multidisciplinary study on an extreme case, where volcanically-triggered deep convection lasted for six days. We show that this unprecedented event was caused and sustained by phreatomagmatic activity at Anak Krakatau volcano, Indonesia during 22–28 December 2018. Our modelling suggests an ice mass flow rate of ~5 × 106 kg/s for the initial explosive eruption associated with a flank collapse. Following the flank collapse, a deep convective cloud column formed over the volcano and acted as a ‘volcanic freezer’ containing ~3 × 109 kg of ice on average with maxima reaching ~1010 kg. Our satellite analyses reveal that the convective anvil cloud, reaching 16–18 km above sea level, was ice-rich and ash-poor. Cloud-top temperatures hovered around −80 °C and ice particles produced in the anvil were notably small (effective radii ~20 µm). Our analyses indicate that vigorous updrafts (>50 m/s) and prodigious ice production explain the impressive number of lightning flashes (~100,000) recorded near the volcano from 22 to 28 December 2018. Our results, together with the unique dataset we have compiled, show that lightning flash rates were strongly correlated (R = 0.77) with satellite-derived plume heights for this event.
Alternaria alternata uses two siderophore systems for iron acquisition
Authors: Voß Benjamin , Kirschhöfer Frank , Brenner-Weiß Gerald , Fischer Reinhard
Published: February 2020

Iron is one of the most abundant elements on earth and essential for life. However, Fe3+ ions are rather insoluble and microorganisms such as fungi may use siderophores as strong chelators for uptake. In addition, free cytoplasmic iron is rather toxic and intracellular siderophores are used to control the toxicity. Siderophores are also important for iron storage. We studied two siderophore systems in the plant necrotrophic fungus Alternaria alternata and show that the non-ribosomal peptide synthase, Nps2, is required for the biosynthesis of intracellular ferricrocin, whereas Nps6 is needed for the formation of extracellular coprogen and coprogen B. Whereas nps2 was dispensable for growth on iron-depleted medium, nps6 was essential under those conditions. nps2 deletion caused an increase in spore formation and reduced pathogenicity on tomato. Our results suggest that A. alternata employs an external and an internal siderophore system to adapt to low iron conditions.
Publisher Correction: Enabling Covert Body Area Network using Electro-Quasistatic Human Body Communication
Authors: Das Debayan , Maity Shovan , Chatterjee Baibhab , Sen Shreyas
Published: February 2020

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Insect pollination: an ecological process involved in the assembly of the seed microbiota
Authors: Prado Alberto , Marolleau Brice , Vaissière Bernard E. , Barret Matthieu , Torres-Cortes Gloria
Published: February 2020

The assembly of the seed microbiota involves some early microbial seed colonizers that are transmitted from the maternal plant through the vascular system, while other microbes enter through the stigma. Thus, the seed microbiota consists of microbes not only recruited from the plant vascular tissues, but also from the flower. Flowers are known to be a hub for microbial transmission between plants and insects. This floral-insect exchange opens the possibility for insect-transmitted bacteria to colonize the ovule and, subsequently, the seed to pass then into the next plant generation. In this study, we evaluated the contribution of insect pollination to the seed microbiota through high-throughput sequencing. Oilseed rape (OSR) flowers were exposed to visits and pollination by honey bees (Apis mellifera), red mason bees (Osmia bicornis), hand pollinated or left for autonomous self-pollination (ASP). Sequence analyses revealed that honey bee visitation reduced bacterial richness and diversity in seeds, but increased the variability of seed microbial structure, and introduced bee-associated taxa. In contrast, mason bee pollination had minor effects on the seed microbiota. Our study provides the first evidence that insect pollination is an ecological process involved in the transmission of bacteria from flowers to seeds.
Author Correction: Eye movement characteristics reflected fatigue development in both young and elderly individuals
Authors: Zargari Marandi Ramtin , Madeleine Pascal , Omland Øyvind , Vuillerme Nicolas , Samani Afshin
Published: February 2020

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Hydrogen abstraction in astrochemistry: formation of ˙CH2CONH2 in the reaction of H atom with acetamide (CH3CONH2) and photolysis of ˙CH2CONH2 to form ketene (CH2CO) in solid para-hydrogen
Authors: Haupa Karolina Anna , Ong Wei-Siong , Lee Yuan-Pern
Published: February 2020

The amide bond of acetamide is unaffected by hydrogen exposure, but the hydrogen abstraction on its methyl site activates this molecule to react with other species to extend its size as a first step to form interstellar complex organic molecules.
Electronic effects of transition metal dopants on Fe(100) and Fe5C2(100) surfaces for CO activation
Authors: Gong Huiyong , He Yurong , Yin Junqing , Liu Suyao , Qing Ming , Peng Qing , Huo Chun-Fang , Wang Hong , Yang Yong , Wen Xiao-Dong
Published: February 2020

Spin polarized density functional theory computations were performed to elucidate electronic effects based on first-row transition metal doped Fe(100) and Fe5C2(100) surfaces for CO dissociation.
Self-oxygenated anatase–rutile phase junction: ensuring the availability of sufficient surface charges for photocatalysis
Authors: Ullattil Sanjay Gopal , Abdel-Wahab Ahmed
Published: February 2020

Oxygen richness induced surface charges at the anatase–rutile interface of yellow TiO2 paved the way for improved photocatalysis.
Amphiphilic poly(esteracetal)s as dual pH- and enzyme-responsive micellar immunodrug delivery systems
Authors: Bixenmann Leon , Stickdorn Judith , Nuhn Lutz
Published: February 2020

Amphiphilic poly(esteracetal) micelles encapsulate potent immune modulatory drugs, but fall apart and release them upon dual pH or enzymatic stimuli.
Design and in vitro/in vivo evaluations of a multiple-drug-containing gingiva disc for periodontotherapy
Authors: Jain Pooja , Mirza Mohd. Aamir , Talegaonkar Sushama , Nandy Shyamasree , Dudeja Mridu , Sharma Nilima , Anwer Md. Khalid , Alshahrani Saad M. , Iqbal Zeenat
Published: February 2020

A gingiva disc of cellulose acetate phthalate and poloxaner F-127 was developed for the simultaneous delivery of multiple drugs, including minocycline, to promote alveolar bone regeneration by abolishing infection, impeding inflammation and averting collagen destruction.
Irreversible hydrodynamic trapping by surface rollers
Authors: Chamolly Alexander , Lauga Eric , Tottori Soichiro
Published: February 2020

A microscopic colloidal roller propelling along a flat rigid surface can irreversibly trap and transport passive cargo through cross-streamline migration induced by steric interaction between the cargo and the interface.
An overview of viscoelastic phase separation in epoxy based blends
Authors: Surendran Anu , Joy Jomon , Parameswaranpillai Jyotishkumar , Anas S. , Thomas Sabu
Published: February 2020

The viscoelastic effects during reaction induced phase separation play an important role in toughening epoxy-based blends.
Amphipathic design dictates self-assembly, cytotoxicity and cell uptake of arginine-rich surfactant-like peptides
Authors: Mello Lucas R. , Aguiar Rodrigo B. , Yamada Renata Y. , Moraes Jane Z. , Hamley Ian W. , Alves Wendel A. , Reza Mehedi , Ruokolainen Janne , Silva Emerson R.
Published: February 2020

Amphiphilicity is the most critical parameter in the self-assembly of surfactant-like peptides, regulating the way by which hydrophobic attraction holds peptides together.
Synthesis, characterization and investigation of synergistic antibacterial activity and cell viability of silver–sulfur doped graphene quantum dot (Ag@S-GQDs) nanocomposites
Authors: Kadian Sachin , Manik Gaurav , Das Neeladrisingha , Nehra Poonam , Chauhan Rishi Pal , Roy Partha
Published: February 2020

In this work, a new nanocomposite (Ag@S-GQDs) have been synthesized using one-step facile synthesis process and their antibacterial as well as cytotoxicity properties were investigated systematically.
Superhydrophobic highly flexible doubly cross-linked aerogel/carbon nanotube composites as strain/pressure sensors
Authors: Zu Guoqing , Wang Xiaodong , Kanamori Kazuyoshi , Nakanishi Kazuki
Published: February 2020

We report novel superhydrophobic highly flexible composites based on a doubly cross-linked aerogel and carbon nanotubes for highly sensitive strain/pressure sensing.
Diphenylamine/triazine hybrids as bipolar hosts for phosphorescent organic light-emitting diodes
Authors: Zhang Yaxing , Zheng Yuanyuan , Wang Binyan , Ran Huijuan , Wang Xiaoli , Hu Jian-Yong , Wang Qiang
Published: February 2020

Bipolar host materials employing diphenylamine as a donor unit and triazine as an acceptor unit have been developed for high performance phosphorescent organic light-emitting diodes.
F108 stabilized CuO nanoparticles for highly selective and sensitive determination of mercury using resonance Rayleigh scattering spectroscopy
Authors: Qasem Mayada , El Kurdi Riham , Patra Digambara
Published: February 2020

This work reportsnon-cross-linking of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) stabilized copper oxide nanoparticles for the detection of mercury ions through the resonance Rayleigh scattering method.
Supramolecular ultrafast energy and electron transfer in a directly linked BODIPY–oxoporphyrinogen dyad upon fluoride ion binding
Authors: Chahal Mandeep K. , Liyanage Anuradha , Gobeze Habtom B. , Payne Daniel T. , Ariga Katsuhiko , Hill Jonathan P. , D’Souza Francis
Published: February 2020

Photosynthetic mimicry of sequential ultrafast energy transfer followed by electron transfer upon fluoride binding to the oxoporphyrinogen cavity in a BODIPY–oxoporphyrinogen dyad is demonstrated.
Unlocking the direct photocatalytic difluoromethylation of CN bonds
Authors: Garrido-Castro Alberto F. , Gini Andrea , Maestro M. Carmen , Alemán José
Published: February 2020

The current study presents a direct CF2H radical addition to CN bonds predicated on the photocatalytic activation of commercially available zinc difluoromethanesulfinate, achieving impressive structural diversity.
Syntheses, crystal structures, dye degradation and luminescence sensing properties of four coordination polymers
Authors: Qin Ling , Hu Qing , Zheng Qi-Ming , Dou Yue , Yang Hu , Zheng He-Gen
Published: February 2020

Four coordination polymers based on the pyridyl-carboxyl ligand have been solvothermally synthesized and characterized. The heterogeneous catalytic oxidation activities of 1–3 and luminescence titration experiments for 4 have been studied.
Determination of the cationic conformational structure of tetrahydrothiophene by one-photon MATI spectroscopy and Franck–Condon fitting
Authors: Lee Yu Ran , Kim Hong Lae , Kwon Chan Ho
Published: February 2020

This study affords more accurate information regarding the pseudorotational PES describing the conformational interconversion of THT.
Underlayer engineering into the Sn-doped hematite photoanode for facilitating carrier extraction
Authors: Zhou Zhongyuan , Wu Shaolong , Xiao Chenhong , Li Liujing , Li Xiaofeng
Published: February 2020

The contributions of different underlayers in the hematite photoanode are revealed, and the underlayers can impact the top/bottom surfaces and bulk properties.
Understanding molecular surface doping of large bandgap organic semiconductors and overcoming the contact/access resistance in organic field-effect transistors
Authors: Pei Ke , Lau Albert Ho Yuen , Chan Paddy Kwok Leung
Published: February 2020

Performance improvement of large bandgap organic semiconductor transistors by surface-doping through a trap filling process.
A Sm-MOF/GO nanocomposite membrane for efficient organic dye removal from wastewater
Authors: Yang Guohai , Zhang Daqing , Zhu Gen , Zhou Tingrong , Song Manting , Qu Lulu , Xiong Kecai , Li Haitao
Published: February 2020

A nanocomposite membrane composed of samarium metal-organic frameworks and graphene oxide nanosheets was fabricated for organic dye removal.
How many ways a cell can move: the modes of self-propulsion of an active drop
Authors: Loisy Aurore , Eggers Jens , Liverpool Tanniemola B.
Published: February 2020

Modelling a cell as a deformable drop of active matter, we classify the types of cell locomotion on solid surfaces based on general physical principles. Previous models are special cases of our framework and we identify a new self-propulsion mode.
Enhancement in electrical conductivity of a porous indium based metal–organic framework upon I2 uptake: combined experimental and theoretical investigations
Authors: Mani Prabu , Mandal Nilangshu , Roopesh Mekkat , Gopalakrishnan Harikrishnan , Datta Ayan , Mandal Sukhendu
Published: February 2020

Combined experimental and theoretical calculations shed light on the enhancement of conductivity through I2 incorporation in an indium metal–organic framework.
Promising crack segmentation method based on gated skip connection
Authors: Jabreel M. , Abdel‐Nasser M.
Published: February 2020

This Letter proposes a promising deep learning‐based method for crack segmentation based on gated skip connection. The proposed gated skip connection enables the decoder layers to promote crack‐aware feature representations from the encoder layers by applying high weights on the crack‐relevant features that come from the encoder layers and lower weights for irrelevant features. Unlike the related methods, the authors do not apply any pre‐processing or refinement steps to improve the crack segmentation results. The proposed method beats the state‐of‐the‐art methods with an open benchmark database (IoU of 87.5).
Independent path‐based process recommendation algorithm for improving biomedical process modelling
Authors: Wang Jiaxing , Tan Dapeng , Cao Bin , Fan Jing , Deep Samundra
Published: February 2020

Process recommendation is an important technique in business process management (BPM), which can be introduced to support modelling biomedical processes. However, most existing process recommendation algorithms in terms of behaviour (what tasks need to be executed in what order) suffer from the problem of state‐space explosion when unfolding a process with many parallel patterns. To address this issue, the authors propose an independent path‐based process recommendation algorithm to speed up the biomedical process recommendation while guaranteeing the accuracy. The experimental results of the proposed algorithm showed higher accuracy and better efficiency than the state‐of‐the‐art algorithms.
Information measure based tone mapping of outdoor LDR image for maximum scale‐invariant feature transform extraction
Authors: Kim Jaewoong , Lee Sukhan
Published: February 2020

A novel tone mapping method referred to here as information measure‐based tone mapping is proposed for extracting the maximum number of scale‐invariant feature transform (SIFT) feature points from outdoor low dynamic range (LDR) images. To this end, first, an image is transformed to YUV colour space in which every pixel is assigned two information scores: forward and inverse scores. The forward and inverse information scores represent the number of neighbour pixels that differ in their intensities from the pixel under consideration by a certain threshold for the respective YUV and inverse YUV images. The proposed tone mapping is then carried out in such a way as to emphasise the pixels of high information scores defined by a weighted sum of forward and inverse information scores. Experimental results show that the proposed method offers superior performance to state‐of‐the‐art methods in terms of the number of features extracted and matched.
Practical method for predicting intended gait speed via soleus surface EMG signals
Authors: Kim J. , Chung S.H. , Choi J. , Lee J.M. , Kim S.‐J.
Published: February 2020

The lack of patient effort during robot‐assisted gait training (RAGT) is thought to be the main factor behind unsatisfactory rehabilitative efficacy among hemiparetic stroke patients. A key milestone to implement patient‐driven RAGT is to predict gait intent prior to actual joint movement. Here, the authors propose a method of predicting step speed intent via surface electromyogram (EMG) signals from the soleus. Six lower‐limb muscles were initially evaluated on a treadmill, and the results suggest that the soleus EMG signals correlate well with step speed. The authors further propose a simple linear regression model which predicts subsequent step speed via current soleus EMG signals with over‐ground gait sessions, of ∼0.6. The proposed experimental results and simple prediction model should be applicable for RAGT without significant modifications.
Cooperative wideband spectrum sensing in cognitive radio based on sparse real‐valued fast Fourier transform
Authors: Khayyeri Mohammad , Mohammadi Karim
Published: February 2020

The Cognitive Radio (CR) plays a key role in identifying free bandwidths in the Radio Frequency (RF) spectrum. High‐speed Analog‐to‐Digital Converters are normally applied for spectrum sensing of sideband signals providing several raw data for digital signal processors resulted in energy‐inefficient complex circuits and hardware resources in digital signal processing blocks. In some instances, the frequency spectrum is sparsely occupied by various users, i.e., only a few active frequency bands exist at the same time. This feature enables CR application to use sub‐Nyquist sampling approaches for designing a system representing significantly reduced cost and power consumption, as well as improved processing speed. The current paper introduced a novel Cooperative Real‐valued Sparse Spread Spectrum Sensing algorithm (CR4S) based on a sub‐Nyquist sampling approach by employing the sparsity of the frequency spectrum and the real‐valued properties of the RF signal to identify free bandwidth with minimum computational complexity. The CR4S algorithm aimed at improving CR spectrum sensing by utilizing techniques such as Real‐valued FFT, Sparse Fast Fourier Transform, and collaborative spectrum sensing. The proposed algorithm has been approved by simulation to above 95% detection performance. The performance enhancement in the CR4S algorithm is an emerging advance being fascinating for portable CR devices.
Idle sense with transmission priority in fibre‐wireless networks
Authors: Hassan Wan Hafiza Wan , Idrus Sevia Mahdaliza , King Horace , Ahmed Shabbir , Faulkner Mike
Published: February 2020

The convergence of fibre and wireless technologies realised the fibre‐wireless (FiWi) networks. Despite huge capacity offered by fibre, the user experiences a network bottleneck caused by the wireless side. This study investigates wireless local area network (WLAN), the wireless side of the FiWi networks with a gigabits passive optical network (GPON) as the backhaul. The work aims to improve WLAN performance by utilising information gained from GPON. The proposed technique enables all contending stations in multiple access points (APs) WLAN to achieve a desired downlink‐to‐uplink transmission ratio, k while maintaining maximum throughput. Optimum contention window (CW) sizes for the APs and associate wireless users (WUs) are derived by incorporating the principles of idle sense (IS) and asymmetric AP. However, fairness problem between WUs occurred when they contend the channel with different CW sizes. Hence, this study simplifies the IS scheme to increase fairness between WUs. Furthermore, AP self‐adapting and WU adjusting algorithms are proposed to assist the network to achieve the desired k, while maintaining the throughput fairness amongst basis service sets. The robustness of the proposed scheme is demonstrated under various conditions: achieved target k with nearly perfect fairness and gained near‐to‐maximum throughput within 96% of the theoretical optimum.
Algorithm for energy consumption minimisation in wireless sensor network
Authors: Kumar Shah Indra , Maity Tanmoy , Singh Dohare Yogendra
Published: February 2020

Wireless sensor network (WSN) consists of spatially distributed miniature size and autonomous nodes along with batteries as a power source. The major bottleneck of WSN is efficient energy utilization. The energy consumption for transmission of signals increases with the distance. This problem of energy consumption is addressed in this study. This study presents a strategy, namely distance‐based dynamic duty‐cycle allocation (DBDDCA) algorithm. In DBDDCA, longer distance nodes from cluster head (CH) transmit relatively less time in order to save energy. Conversely, transmit for the higher time when the distance is near to CH. The proposed DBDDCA is compared with the other existing strategies: low‐energy adaptive cluster hierarchy (LEACH), modified leach, and stable election protocol and with two existing medium access control (MAC) protocols: sensor (S)‐MAC and timeout (T)‐MAC. The performance of the proposed and existing strategies is evaluated with the following network parameters: energy consumption, network energy utilization, network lifetime, latency, and packets delivery. These parameters have been evaluated with different network scenarios such as number of nodes increases, number of rounds, and with variation in initial energy of nodes. Simulation results show the performance of the proposed strategy is significantly better than the existing strategies under the investigated network parameters.
Filtering enhanced tomographic PIV reconstruction based on deep neural networks
Authors: Liang Jiaming , Cai Shengze , Xu Chao , Chu Jian
Published: February 2020

Tomographic particle image velocimetry (Tomo‐PIV) has been successfully applied in measuring three‐dimensional (3D) flow field in recent years. Such technology highly relies on the reconstruction technique which provides the spatial particle distribution by using images from multiple cameras at different viewing angles. As the most popular reconstruction method, the multiplicative algebraic reconstruction technique (MART) has advantages in high computational speed and high accuracy for low particle seeding reconstruction. However, the accuracy is not satisfactory in the case of dense particle distributions to be reconstructed. To overcome this problem, a symmetric encode–decoder fully convolutional network is proposed in this paper to improve the reconstruction quality of MART. The input of the neural network is the particle field reconstructed by the MART approach, while the output is the regenerated image with the same resolution. Numerical evaluations indicate that those blurred or irregular particles can be significantly refined by the trained neural network. Most of the ghost particles can also be removed by this filtering method. The reconstruction accuracy can be improved by more than 10% without increasing the computational cost. Experimental evaluations indicate that the trained neural network can also provide similar satisfactory reconstruction and improved velocity fields.
Survey of unmanned subterranean exploration, navigation, and localisation
Authors: Martz Jeffrey , Al‐Sabban Wesam , Smith Ryan N.
Published: February 2020

Subsurface networks include mining tunnels, caves, and the urban underground. Each of these environments presents a complex setting with significant challenges in exploration, exploitation, etc. Multiple hazards exist, including environmental and structural, and conditions degrade and change temporally. We present a survey of research in autonomy, networking and mobility focused on exploring and/or mapping subsurface networks in unpredictable and unexplored environments. The focus is on mining tunnels as a proxy subterranean environment; motivated by the proximity of the authors to the Bonita Peak Mining District; a Superfund site consisting of 48 historic mines which have contaminated soil, groundwater and surface water with heavy metals as a result of historic practices. The exploration and assessment of the mining tunnels for remediation efforts presents an extremely challenging problem in subterranean navigation. Arguably, the environment in question is the most extreme and challenging subterranean environment. Unmanned assets must enter to explore and re‐map the tunnels to assess safety for subsequent entrance by robots and/or humans for proper remediation. The survey is split into three categories — Locomotion, GPS‐denied navigation and localization, and Communication. It is concluded with a proposed design for a platform that addresses the difficulties of exploring an abandoned mine
Investigations into series resonant inverter power control parameters for an effective metal induction surface hardening
Authors: Attab Abdelkader , Zeroug Houcine , Hammouma Chabane
Published: February 2020

Metal hardening depends on the material properties and the way the heat is being applied; therefore, a careful induction heating system parameter should be carefully selected, and in particular to meet the hardening requirements. In this study, a focus on a cost‐effective design of the induction coil and the converter is presented. For that, a sample bar metal made of XC48 is considered. The methodology exploits an indirect procedure. It starts from the coil design according to the metal sample size, followed by a 2D finite element method for parameters and losses determination for the specified hardening depth. The power supply using resonant series converters is evaluated through electrical modelling simulation and which integrates a phase‐locked loop scheme to account for load parameter variation. A comparison between the electrical and heat power is conducted to highlight the importance of the inverter control parameters leading to high efficiency and an appropriate and satisfactory hardening profile. A prototype system is built to demonstrate the effectiveness of the approach described.
Analytical thermal model and flow network analysis suitable for open self‐ventilated machines
Authors: Shams Ghahfarokhi Payam , Kallaste Ants , Belahcen Anouar , Vaimann Toomas
Published: February 2020

This study provides a survey on thermal and flow network analysis of open self‐ventilated (OSV) machines. The improvements and new approaches proposed in the last decade are analysed in detail. The thermal analysis of OSV machines is divided into two significant steps, thermal models and flow network analysis. In the first step of this survey, the analytical thermal model approach is considered in detail. In addition, the study provides an overview of the critical parameters of an analytical thermal model and discusses different solutions to overcome the problems. In the second step, the hydraulic behaviour of OSV machines is considered by using the analytical flow network analysis and the formulation to calculate the flow network parameters is provided.
Semidefinite relaxation and generalised benders decomposition to solve the transmission expansion network and reactive power planning
Authors: Alvarez Erik F. , Paredes Miguel , Rider Marcos J.
Published: February 2020

This study presents a methodology to solve simultaneously the alternating current (AC) transmission network expansion and reactive power planning problems, considering multiple stages and operating conditions. A mixed‐integer non‐linear programming model for the proposed planning problem is presented and rewritten with semidefinite structures. Then, the generalised Benders decomposition is used to separate the overall problem into an upper‐level (master) problem and several lower‐level (slaves) problems. The master problem is a mixed‐integer linear programming problem that optimises the investment cost and constraints of the multistage expansion. Each slave problem minimises the operating costs associated with each stage and operating condition (normal operation or contingency), considering the AC power flow via semidefinite relaxation. With the proposed methodology, the global optimality of generalised Benders decomposition can be preserved due to the use of semidefinite relaxation in each slave problem. Garver's 6‐bus system and an IEEE 118‐bus system are used to show the precision and convergence to near‐global optimal solutions with small relaxation gaps through the proposed approach.
Settings determination for numerical transformer differential protection via its detailed mathematical model
Authors: Andreev Mikhail , Suvorov Alexey , Ruban Nikolay , Ufa Ruslan , Gusev Alexander , Askarov Alisher , Kievets Anton , Bhalja Bhavesh R.
Published: February 2020

Currently, an issue of relay protection (RP) settings determination that ensures its correct operation in electric power systems (EPSs) has not been resolved completely. The main reason for this is the lack of methods and tools for adequate consideration of transients during a fault existence for RP settings calculation. In this study, a novel approach for RP settings determination is presented. Its main feature is the application of detailed mathematical models reproducing simultaneously processes in the entire set of elements in the RP scheme, including instrumental transformers, and in large‐scale EPS mathematical model as a whole. This key feature can be achieved via the hybrid power system simulator – hybrid real‐time power system simulator – implementing a methodically accurate analogue–digital solution of the EPS mathematical model. The numerical transformer differential protection (NTDP) based on this approach was set up via the standard dual‐slope tripping characteristic. Also, a novel approach to the formation of the tripping characteristic is proposed. The key feature of this approach is applying a flexible curve that enveloping all fault characteristics Idiff = f (Irest) of those modes in which the NTDP should not trip.
Flexible hybrid state estimation for power systems with communication irregularities
Authors: Švenda Vanja G. , Stanković Aleksandar M. , Sarić Andrija T. , Transtrum Mark K.
Published: February 2020

This study proposes a novel flexible hybrid state estimation (SE) algorithm when a realistic communication system with its irregularities is taken into account. This system is modelled by the Network Simulator 2 software tool, which is also used to calculate communication delays and packet drop probabilities. Within this setup, the system observability can be predicted, and the proposed SE can decide between using the static SE (SSE) or the discrete Kalman filter plus SSE‐based measurements and time alignment (Forecasting‐aided SE). Flexible hybrid SE (FHSE) incorporates both phasor measurement units and supervisory control and data acquisition‐based measurements, with different time stamps. The proposed FHSE with detailed modelling of the communication system is motivated by: (i) well‐known issues in SSE (time alignment of the measurements, frequent un‐observability for fixed SE time stamps etc.); and (ii) the need to model a realistic communication system (calculated communication delays and packet drop probabilities are a part of the proposed FHSE). Application of the proposed algorithm is illustrated for examples with time‐varying bus load/generation on two IEEE test cases: 14‐bus and 300‐bus.
Start‐up circuit for an electric vehicle fast charger using SSICL technique and a slow estimator
Authors: Tashakor Nima , Arabsalmanabadi Bita , Ghanbari Teymoor , Farjah Ebrahim , Götz Stefan
Published: February 2020

With the increase in power rating of electric vehicle chargers, concerns regarding their integration to the grid have likewise grown. This paper investigates a novel technique for start‐up of high‐power fast electric vehicle (EV) charger using a solid‐state inrush current limiter (SSICL). The circuit consists of three similar sets of bidirectional switch and limiting resistor that utilizes a control strategy based on a simple Kalman filter (KF) to suppress the converter start‐up current and transient over‐voltages. In fact, the built‐up profile of the inrush current is dictated in accordance with the estimated current by the slow dynamic KF. Compared to alternatives, such as start‐up resistors, the presented SSICL achieves faster start‐up with comparable peak current, tends to provide lower distortion, and provides a good balance between speed and efficiency. Simulation and experimental results confirm that the proposed method can considerably suppress inrush currents, while improving the total harmonic distortion. Comparing the behaviour of the SSICL to other relevant techniques underlines the advantages of the proposed solution. Furthermore, although the focus of this paper is start‐up of the fast EV chargers, the proposed circuit can act as an inrush‐current limiter in most AC to DC converter structures.
Multi‐dimensional data modelling of video image action recognition and motion capture in deep learning framework
Authors: Gao Peijun , Zhao Dan , Chen Xuanang
Published: February 2020

In order to improve the accuracy of small‐range human motion recognition in video and the computational efficiency of large‐scale data sets, a multi‐dimensional data model of motion recognition and motion capture in video image based on deep‐learning framework was proposed. First, the moving foreground of the target is extracted by the Gauss mixture model, and the human body is recognised by the gradient histogram. At the second level, the dense trajectory feature and the deep learning feature are fused, according to the integration of global encoding algorithm and convolutional neural network. In the deep learning feature, the fusion of the deep video feature and the video RGB tricolour feature is taken as the feature of deep learning. Finally, the classification is based on the deep learning network model. The simulation experiments based on large‐scale real data sets and small‐scale gesture data sets show that the algorithm has high recognition accuracy for large‐scale data sets and small‐scale gesture actions. In addition, Imperial Computer Vision & Learning Lab human behaviour data set is used to classify the experimental data. The average classification accuracy is 85.79%. The algorithm can run at a speed of about 20 frames per second.
Optimised robust watermarking technique using CKGSA in DCT‐SVD domain
Authors: Singh Roop , Ashok Alaknanda , Saraswat Mukesh
Published: February 2020

Digital watermarking embeds a watermark to minimise the problem of illegal copying and disseminating multimedia contents. However, the existing techniques do not maintain the imperceptibility and robustness simultaneously. To achieve the same, this study proposes an optimised robust watermarking technique using chaotic kbest gravitational search algorithm. The chaotic kbest gravitational search algorithm is used to obtain the optimal values of embedding factors. The efficacy of the proposed technique has been experimented on a standard images and compared with the six recent state‐of‐the‐art techniques in terms of imperceptibility and robustness. The experimental results validate that the proposed technique outperforms the other considered techniques.
Predicting station level demand in a bike‐sharing system using recurrent neural networks
Authors: Chen Po‐Chuan , Hsieh He‐Yen , Su Kuan‐Wu , Sigalingging Xanno Kharis , Chen Yan‐Ru , Leu Jenq‐Shiou
Published: February 2020

The modern multi‐modal transportation system has revolutionised the landscape of public mobility in cities around the world, with bike‐sharing as one of its vital components. One of the critical problems in persuading citizens to commute using the bike‐sharing service is the uneven bikes distribution which leads to bike shortage in certain locations, especially during rush hours. This study offers a system, which provides predictions of both rental and return demand in real‐time for each bike station by using only one model, which can be used to formulate load balancing strategies between stations. Five different architectures based on recurrent neural network are described and compared with four evaluation metrics: mean absolute percentage error, root mean squared logarithmic error, mean absolute error and root mean squared error. This system has been tested with New York Citi Bike dataset. The evaluation shows the authors’ proposed methods demonstrate satisfying results at both the global and station levels.
Quad‐mode radial uniform circular array antenna for OAM multiplexing
Authors: Yoo Jeong‐Ung , Son Hae‐Won
Published: February 2020

This study presents a novel radial uniform circular array (UCA) antenna for quad‐mode orbital angular momentum (OAM) multiplexing in the 5.2 GHz band. The antenna can simultaneously generate four OAM modes (±1, ±2) using two radial UCAs printed concentrically on a single substrate. Each UCA is connected to an individual dual‐mode feeding network, and generates a pair of complementary OAM modes. The feeding network for each UCA consists of one quadrature hybrid coupler and two circular feedlines, and they can be integrated onto a single substrate. The measured radiation patterns and helical phase wavefronts show the successful generation of four OAM modes by the proposed antenna. The quad‐mode OAM transmission test was performed using two prototypes of the proposed antenna, and good isolations >13.7 dB were obtained between four OAM mode channels, which demonstrates that the antenna can be successfully used for OAM multiplexing.
Improvement of the power quality of single‐phase grid‐connected inverter by filter‐based control scheme
Authors: Alqatamin Moath , McIntyre Michael L.
Published: February 2020

In this study, a filter‐based control scheme is developed for a single‐phase grid‐connected inverter system with the local load. Improving the quality of the local load voltage in the grid‐connected mode and injecting clean current to the grid at the same time is the main objective of the proposed scheme. Moreover, unity power factor at the grid side for different types of the local load is ensured by the proposed controller. Furthermore, this control approach ensures the seamless transfer between grid‐connected and stand‐alone operation modes without adjusting the controller structure and without any resynchronisation scheme. The proposed scheme is validated by the Lyapunov stability analysis. Moreover, an experimental testbed has been implemented to further validate the controller in the real‐time environment, as well as, the performance is compared to a conventional approach.
Modulation strategy for improving the voltage gain of the dual‐active‐bridge converter
Authors: Lu Junlong , Wang Yibo , Wang Huan , Wei Miaomiao , Zhou Yu , Zhang Yubo
Published: February 2020

A novel modulation strategy for improving the voltage gain of a dual‐active‐bridge converter is proposed herein. Under the strategy, the converter performs a high‐voltage gain under a low transformer turns ratio, thereby improving the transmission efficiency of the transformer because the large turns ratio typically results in large parasitic parameters, such as leakage inductance or distributed capacitance. In addition, voltage spikes can be avoided as the energy caused by leakage inductance is recycled to the output side. The operating principle of the proposed modulation strategy is discussed in detail herein. Moreover, the zero‐voltage switching conditions in both buck and boost modes are analysed and derived. Finally, a prototype with a 350 V high voltage, 48 V low voltage, and 1 kW output power is established, and the conversion efficiencies of 94.2% in buck mode and 93.2% in boost mode are obtained. Experimental results verify the validity of the proposed modulation strategy.
Approach for classifying continuous control set‐predictive controllers applied in AC motor drives
Authors: Vafaie Mohammad Hossein
Published: February 2020

In this article, basic concepts, operating principles and important characteristics of continuous control set‐predictive controllers (CCS‐PCs) applied to AC motors are explained in detail. Based on the existence or absence of cost function as well as the method used to find the optimal control action, CCS‐PCs can be categorised into the following three categories: predictive controllers without cost function, predictive controllers with a cost function (or model predictive controllers) and deadbeat controllers. To identify the advantages and disadvantages of each category, one of the recent algorithms of each category is selected and implemented experimentally. Then, various experimental tests are conducted where performances of all the algorithms are assessed in a comprehensive manner by evaluating stator‐flux ripple, torque ripple, stator current harmonics, robustness against parameter changes, computational complexity, memory requirement and torque dynamic response. To achieve general and meaningful conclusions, the analysis is performed on a traditional three‐phase two‐level voltage source inverter used to control an interior permanent‐magnet synchronous motor. Based on the theoretical discussions and experimental results, it is indicated that which category of CCS‐PCs can be adopted in high performance AC motor drives.
Photocatalytic properties of ZnO thin film with different morphologies from seed, array to grass
Authors: Wang Zhaopeng , Ye Xiaoyun , Chen Long , Zhang Leilei , Wang Qianting , Ma Lian , Hua Nengbin
Published: February 2020

ZnO thin film with different morphologies from seed, array to grass was grown by simple aqueous solution method under room temperature. The morphologies, structure, optical properties and photocatalytic properties of the samples were characterised by transmission electron microscope, scanning electron microscope, X‐ray diffraction, fluorescence spectrometer, UV–Vis spectrophotometer and photocurrent response. The results showed that the ZnO arrays and grassy ZnO were both hexagonal wurtzite with uniform distribution and regular growth on the glass substrate. ZnO thin film with different morphologies affected the utilisation efficiency of the ultraviolet light. Multiple light reflections inside the grassy ZnO greatly increase the light efficiency. The methyl blue degradation rate of grassy ZnO photocatalyst was superior under the UV light compared to the other ZnO morphologies. Grassy ZnO showed favourable stability after five cycles. The comparison of the ZnO semiconductor in different dimensions is helpful for further research on other photocatalysts as well as their potential application.
Stellar activity consequence on the retrieved transmission spectra through chromatic Rossiter-McLaughlin observations
Authors: Boldt S. , Oshagh M. , Dreizler S. , Mallonn M. , Santos N. C. , Claret A. , Reiners A. , Sedaghati E.
Published: February 2020

Mostly multiband photometric transit observations have been used so far to retrieve broadband transmission spectra of transiting exoplanets in order to study their atmosphere. An alternative method has been proposed and has only been used once to recover transmission spectra using chromatic Rossiter-McLaughlin observations. Stellar activity has been shown to potentially imitate narrow and broadband features in the transmission spectra retrieved from multiband photometric observations; however, there has been no study regarding the influence of stellar activity on the retrieved transmission spectra through chromatic Rossiter-McLaughlin. In this study with the modified SOAP3.0 tool, we consider different types of stellar activity features (spots and plages), and we generated a large number of realistic chromatic Rossiter-McLaughlin curves for different types of planets and stars. We were then able to retrieve their transmission spectra to evaluate the impact of stellar activity on them. We find that chromatic Rossiter-McLaughlin observations are also not immune to stellar activity, which can mimic broadband features, such as Rayleigh scattering slope, in their retrieved transmission spectra. We also find that the influence is independent of the planet radius, orbital orientations, orbital period, and stellar rotation rate. However, more general simulations demonstrate that the probability of mimicking strong broadband features is lower than 25% and that can be mitigated by combining several Rossiter-McLaughlin observations obtained during several transits.