bluuebunny/crossref_metadata_2025 huggingface dataset:
Global Geochemical Baseline Mapping in India for Environmental Management Using Topsoil
Authors: Govil Pradip K. , Krishna A. Keshav , Dimri V. P.
Published: January 2020

As a part of International Union of Geological Sciences (IUGS)/ International Association of Geochemistry (IAGC) Task Group on Global Geochemical Baselines, CSIR-National Geophysical Research Institute (CSIR-NGRI), Hyderabad, India has carried out geochemical baseline mapping of India to provide high quality data for a wide range of environmental applications. A project based on IUGS global baselines project was initiated by NGRI to cover the whole of India which is having 122 Global Terrestrial Network (GTN)/Global Reference Network (GRNs) of 160 x 160 km. Soil samples were studied in 115 out of the 122 GRN cells in India. 544 topsoil samples were collected for these studies. The soil samples were collected as per the guidelines given in the IUGS/IAGC field manual. The samples were analyzed for 10 major and 12 trace elements (SiO2, Al2O3, Fe2O3, MnO, MgO, CaO, Na2O, K2O, TiO2, P2O5, Ba, Co, Cr, Cu, Ni, Pb, Rb, Sr, V, Y, Zn and Zr) by X-ray fluorescence spectrometer at NGRI. The analytical data were computed to prepare geochemical maps showing the distribution of major oxides and trace elements all over India. These maps will help to know the distribution of the toxic and hazardous metals and their relation to human health. These maps also help to see the hot spots for the entire country and in suggesting remedial measures.
The “Lower Kaimur Porcellanite” (Vindhyan Supergroup) is of Sedimentary Origin and not Tuff
Authors: Choudhuri Adrita , Schieber Juergen , Sarkar Subir , Bickford Marion E. , Basu Abhijit
Published: January 2020

The ‘Lower Kaimur Porcellanite’ from the Proterozoic Vindhyan Supergroup (~1700-900? Ma) is not only a chronostratigraphic marker but also an indicator of the tectonic setting of the basin. A few other silicified shaly units (porcellanites) from the upper strata have been thought to be tuff. New petrographic (optical microscopic; SEM-BSE), chemical, and U-Pb zircon geochronological studies of the lowermost of these suspected tuff units, however, do not support an igneous origin for these beds. The rocks do not contain phenocrysts or glass shards, but contain remains of mineralized microbial spheres, mudclasts, and other detrital grains that include one datable zircon grain (~1715 Ma). Their chemical compositions are not diagnostic of tuff. Despite this result, investigations of other porcellanites from Upper Vindhyan strata is recommended, because they have the potential of identifying crucially important tuff beds.
Sub-watershed Prioritization Based on Drainage Morphometric Analysis: A Case Study of Cauvery River Basin in South India
Authors: Arulbalaji P. , Padmalal D.
Published: January 2020

Prioritization of sub-watersheds in a river basin using morphometric parameters is one of the simplest approaches for development of watersheds for its use and management. In this perspective, a study has been undertaken in the Cauvery river basin in South India, using morphometric analysis of the entire river basin in relation to its 17 sixth order sub-watersheds. In this study, automated extraction of drainage network method was applied using geospatial techniques. Drainage morphometric analysis was performed through linear, aerial and relief aspects. Strahler stream order classification was applied for classifying the stream order. In general, dendritic and sub-dendritic types of drainage patterns are noticed in the Cauvery river basin. The total length of the river and basin area are 800 km and 82283 km2, respectively. Hypsometric analysis reveals that about 30% of the study area is covered by steep slope with deeply dissected landscapes and the remaining 70% spreads essentially in the Mysore plateau and Tamil Nadu plains which are generally having gentle slopes with an equilibrium stage of landscape development. Prioritization of sub-watershed was carried out based on compound parameter analysis by adding the values of linear and shape parameters of each sub-watershed. The results of prioritization of sub-watersheds reveal that about 88% of sub-watersheds that spread in the river basin fall under high and moderate priority categories for water resource developments. Only two subwatersheds fall under the low priority category which in turn are safe in the case of water resource development. The study warrants the need for more focused investigations and corrective measures including construction of appropriate recharge structures for improving the water potential of the river basin.
Assessment of Ground Water Quality of Central and Southeast Districts of NCT of Delhi
Authors: Bidhuri Swati , Khan Mohd Mazhar Ali
Published: January 2020

The river Yamuna has become a waste water reservoir due to the disposal of municipal and industrial waste into the river. Most of the water treatment plants are either not working at all or they are overloaded for their respective capacities. Yamuna is the main source for the replenishment of ground water in the study area. Hence the assessment of ground water quality seems to be essential. The present study is confined to evaluate the groundwater quality of central and southeast districts of NCT of Delhi. In this study, arithmetic weighted water quality index (WQI) method is applied for analysing the quality of groundwater. Spatial interpolation model was applied to depict the groundwater quality potentiality map of the area. The results so obtained reveal that the groundwater of the study area is completely unpotable for drinking as well as for other domestic usage without proper treatment because maximum part of the study area exhibits a very high WQI value.
Evaluation Method of ARAS Combining Simulator Experiment and Computer Simulation in Terms of Cost-Benefit Analysis
Authors: Lee Joohyeong , Ozaki Ikumi , Kishino Saya , Suzuki Keisuke
Published: January 2020

In this study, we propose an evaluation method for an Advanced Rider Assistance System (ARAS) for two-wheeled vehicles, combining riding simulator experiments and computer simulations in terms of cost-benefit analysis. This evaluation method focuses on the collision warning system at intersections using an ARAS for two-wheeled vehicles. The study was carried out experiments with 30 test subjects who have two-wheeled vehicle licenses and are not novice riders. To quantify the accident-reduction effect, a Monte-Carlo simulation based on a time-series reliability model was used. Based on the collision probability results derived from the Monte-Carlo Simulation, the overall error probability as a human-machine system was calculated based on an integrated error model. In addition, cost-benefit analysis was conducted to quantify the social benefits and costs of introducing the ARAS to the market. As a result, we confirmed that the system can be beneficial after 4 years when introduced into the market.
Is the IDH Mutation a Good Target for Chondrosarcoma Treatment?
Authors: Cojocaru Elena , Wilding Christopher , Engelman Bodil , Huang Paul , Jones Robin L.
Published: January 2020

Chondrosarcomas are rare cancers of bone that arise from the malignant transformation of cells of chondrocytic lineage. They are known to be resistant to systemic cytotoxic chemotherapy and radiotherapy. The mainstay of management of localised disease is en bloc surgical resection with curative intent. Metastatic chondrosarcoma has a dismal prognosis, and to date, there are no proven effective systemic therapies in the advanced setting. Genomic studies have demonstrated that 50 to 80% of chondrosarcomas harbour a mutation in either the IDH1 or IDH2 gene. IDH inhibitors are currently under investigation in clinical trials, after showing promising results in phase 1 studies in IDH mutated cancers. In chondrosarcoma, IDH mutations represent an attractive target, however, early results with IDH inhibitors in IDH mutated chondrosarcoma are modest and the final results of ongoing trials are eagerly awaited.
shinyChromosome: An R/Shiny Application for Interactive Creation of Non-Circular Plots of Whole Genomes
Authors: Yu Yiming , Yao Wen , Wang Yuping , Huang Fangfang
Published: January 2020

Non-circular plots of whole genomes are natural representations of genomic data aligned along all chromosomes. Currently, there is no specialized graphical user interface (GUI) designed to produce non-circular whole genome diagrams, and the use of existing tools requires considerable coding effort from users. Moreover, such tools also require improvement, including the addition of new functionalities. To address these issues, we developed a new R/Shiny application, named shinyChromosome, as a GUI for the interactive creation of non-circular whole genome diagrams. shinyChromosome can be easily installed on personal computers for own use as well as on local or public servers for community use. Publication-quality images can be readily generated and annotated from user input using diverse widgets. shinyChromosome is deployed at http://150.109.59.144:3838/shinyChromosome/, http://shinyChromosome.ncpgr.cn, and https://yimingyu.shinyapps.io/shinyChromosome for online use. The source code and manual of shinyChromosome are freely available at https://github.com/venyao/shinyChromosome.
A discussion of single-use plastics in medical settings
Authors: Jahnke Ashlee
Published: January 2020

Traditional petroleum-based plastics such as polypropylene (PP) and acrylonitrile butadiene styrene (ABS) are commonly used in medical applications to deliver potentially life-saving treatment and ongoing healthcare to patients around the world. Unfortunately, many of these applications of plastics are single use, leading to many pieces of medical paraphernalia lying in landfill or floating in our oceans. These single-use applications are unavoidable. We propose moving to a newly invented biopolymer platform to resolve the problem.
Closing the circle with recycled carbon fiber
Authors: Nickels Liz
Published: January 2020

A UK company has recently increased its capacity for parts using recycled carbon fiber prepreg. I spoke to Prodrive Composites about the potential for this market in a variety of industries.
New set of properties for polymers: Graphene nanotubes discussed at NAUM’19
Authors: Zirka Anastasia
Published: January 2020

Graphene nanotubes grant engineers the ability to produce totally new, highly innovative and competitive products. Wind turbines, tires, anti-static packaging and clothes, home and industrial electronics, car parts – the number of graphene nanotube-enhanced polymer applications is growing fast, building an ecosystem of greater efficiency and durability around us. 450 experts from 31 country at NAUM’19 Industry Summit in Kyoto discussed the combination of conductivity, strength and the greater control over color that is now possible thanks to these tiny tubes.
Information‐Based Machine Learning for Tracer Signature Prediction in Karstic Environments
Authors: Mewes B. , Oppel H. , Marx V. , Hartmann A.
Published: January 2020

Karstic groundwater systems are often investigated by a combination of environmental or artificial tracers. One of the major downsides of tracer‐based methods is the limited availability of tracer measurements, especially in data sparse regions. This study presents an approach to systematically evaluate the information content of the available data, to interpret predictions of tracer concentration from machine learning algorithms, and to compare different machine learning algorithms to obtain an objective assessment of their applicability for predicting environmental tracers. There is a large variety of machine learning approaches, but no clear rules exist on which of them to use for this specific problem. In this study, we formulated a framework to choose the appropriate algorithm for this purpose. We compared four different well‐established machine learning algorithms (Support Vector Machines, Extreme Learning Machines, Decision Trees, and Artificial Neural Networks) in seven different karst springs in France for their capability to predict tracer concentrations, in this case SO42− and NO3−, from discharge. Our study reveals that the machine learning algorithms are able to predict some characteristics of the tracer concentration, but not the whole variance, which is caused by the limited information content in the discharge data. Nevertheless, discharge is often the only information available for a catchment, so the ability to predict at least some characteristics of the tracer concentrations from discharge time series to fill, for example, gaps or increase the database for consecutive analyses is a helpful application of machine learning in data sparse regions or for historic databases.
Competing Topographic Mechanisms for the Summer Indo‐Asian Monsoon
Authors: Acosta R. P. , Huber M.
Published: January 2020

The Indo‐Asian Monsoon (IAM) has changed as the topographies of Asia were assembled into their current configuration. Understanding complex interactions between topography and the IAM through time has been hampered, in part, by poorly resolved topography and atmospheric dynamics in climate models. Here, we employ high‐resolution (0.23° × 0.31°) global climate simulations, to more accurately capture these interactions. We find that the Himalayas and Tibet primarily redirect the onshore moisture transport and produce local orographic precipitation. The Iranian Plateau is the primary gatekeeper, insulating the pool of high‐enthalpy air in the Indo‐Gangetic Plain (IGP) from westerly low‐enthalpy advection. But, even when such high‐enthalpy air exists along the IGP, vigorous precipitation in the region (poleward of 25°N) still requires orographic steering and lifting. The large‐scale circulations—largely governed by sea surface temperature gradients—robustly advect water vapor onshore regardless of topography. Thus, neither topography nor localized enthalpy air drives onshore monsoon flow.
Intermodel Uncertainty in the Projection of the Anomalous Western North Pacific Anticyclone Associated With El Niño Under Global Warming
Authors: Wu Mingna , Zhou Tianjun , Chen Xiaolong , Wu Bo
Published: January 2020

Based on 34 coupled models from Phase 5 of the Coupled Model Intercomparison Project, we found that the projected changes in the western North Pacific anomalous anticyclone (WNPAC) during El Niño decaying summers show large spread among the models due to different decaying paces of El Niño. Models with a slower (faster) decaying El Niño are followed by weakened (intensified) tropical central Pacific cooling, which further drives a weaker (stronger) WNPAC through inducing weakened (intensified) descending Rossby waves to its west. The decaying pace of El Niño is dominated by the wintertime WNPAC because the easterly surface wind anomalies to its southern flank are critical to El Niño demise. Both the El Niño‐related sea surface temperature anomaly and the precipitation sensitivity to such kind of sea surface temperature anomaly under global warming could affect the wintertime WNPAC.
Predicting the Downward and Surface Influence of the February 2018 and January 2019 Sudden Stratospheric Warming Events in Subseasonal to Seasonal (S2S) Models
Authors: Rao Jian , Garfinkel Chaim I. , White Ian P.
Published: January 2020

Using the real‐time predictions from 11 models, this study analyzes the prediction of the downward propagation and surface impact of the 2018 and 2019 sudden stratospheric warmings (SSWs). These two SSWs differed both in their morphology types (2018: split; 2019: displacement followed by split) and magnitudes (the former being stronger). With a large sample size (>2,200) of multimodel ensemble forecasts, it is revealed that the strength of the SSW is more important than the vortex morphology in determining the magnitude of its downward impact, with strong SSWs more likely to propagate downward than weak SSWs. Therefore, based on the probabilistic forecasts, the observed strong SSW in February 2018 was more likely to have a downward and surface impact than the January 2019 SSW. The relationship between the 10‐hPa dominant wave number and the 100‐hPa polar cap height (or the Northern Annular Mode) is weak, implying that the dominant wave number might not be the primary factor determining the downward propagation of SSWs in the two analyzed cases. Hence, the high polar cap height (or negative Northern Annular Mode) response in the lower stratosphere and troposphere following the February 2018 SSW is mainly attributed to its strong intensity rather than the split morphology. Further, the 2‐m temperature anomaly pattern following the January 2019 SSW is not forecasted due to its weak downward propagation, whereas the 2‐m temperature in North Eurasia, Middle East, south China, and eastern United States could be forecasted for the downward propagating February 2018 SSW. However, regional rainfall anomalies are poorly forecasted (both in a deterministic and probabilistic sense) for both SSWs.
Precession‐ and Obliquity‐Induced Changes in Moisture Sources for Enhanced Precipitation Over the Mediterranean Sea
Authors: Bosmans J.H.C. , van der Ent R.J. , Haarsma R.J. , Drijfhout S.S. , Hilgen F.J.
Published: January 2020

Enhanced winter precipitation over the Mediterranean Sea at times of minimum precession and maximum obliquity, that is, times of enhanced insolation seasonality, could provide freshwater required to form orbitally paced sedimentary cycles across the Mediterranean, offering a possible alternative to monsoonal runoff. We investigate the sources of the enhanced winter precipitation, by applying a moisture tracking model on the results of idealized orbital extreme experiments with a state‐of‐the‐art climate model. Precession and obliquity enhance precipitation in fall and winter. Our study shows that the source of enhanced precipitation over the Mediterranean Sea differs during the winter half‐year. In fall, the majority of the precession‐induced precipitation increase originates from the Mediterranean itself. However, in late winter, the increase can be attributed to enhanced moisture advection from the Atlantic. This agrees with changes in evaporation and air‐sea temperature differences over the Mediterranean. The obliquity‐induced precipitation increase shows much less differences, with an equal contribution of local and Atlantic sources. The mechanism behind the Atlantic source of moisture, particularly important in late winter for precession‐induced precipitation changes, is related to a weakened Azores High and slightly higher surface pressure over North Africa. The resulting anomalous circulation patterns generate enhanced Atlantic moisture transport toward the Mediterranean. These mechanisms coincide with weaker storm track activity over the North Atlantic, opposite to previous studies that often attribute enhanced Mediterranean winter precipitation to a southward shift and intensification of the Atlantic storm track. We thus provide an alternative mechanism for Atlantic sources of orbitally paced Mediterranean precipitation changes.
Who Are we Measuring and Modeling for? Supporting Multilevel Decision‐Making in Watershed Management
Authors: Bremer Leah L. , Hamel Perrine , Ponette‐González Alexandra G. , Pompeu Patricia V. , Saad Sandra I. , Brauman Kate A.
Published: January 2020

As watershed management programs have become more common globally, so have efforts to support these initiatives through hydrologic modeling and monitoring. However, these efforts are often guided by oversimplified assumptions of how management programs work and the quantity, quality, and type of information needed to support their planning, implementation, and evaluation. Semi‐structured interviews and focus groups with project managers, funders, and participants in three watershed management programs in the Atlantic Forest of Brazil revealed a range of hydrologic modeling and monitoring needs of watershed management programs. We identify five opportunities for hydrologic information to support overlapping management contexts: (1) inspire action and support, (2) inform investment decisions, (3) engage with potential participants, (4) prioritize location and types of activities at regional to national scales, and (5) evaluate program success. Within these opportunities, understanding who will use the information generated and how they will do so is critical to increasing the salience, credibility, and legitimacy of modeling efforts. Hydrologic modeling and monitoring play a small but critical role in the larger context of program conceptualization, design, implementation, and evaluation; grounding these efforts in local contexts supports watershed management projects in relevant and effective ways.
Satellite Gravimetry Improves Seasonal Streamflow Forecast Initialization in Africa
Authors: Getirana Augusto , Jung Hahn Chul , Arsenault Kristi , Shukla Shraddhanand , Kumar Sujay , Peters‐Lidard Christa , Maigari Issoufou , Mamane Bako
Published: January 2020

West Africa is one of the poorest regions in the world and highly vulnerable to extreme hydrological events due to the lack of reliable monitoring and forecast systems. For the first time, we demonstrate that initial hydrological conditions informed by satellite‐based terrestrial water storage (TWS) estimates improve seasonal streamflow forecasts. TWS variability detected by the Gravity Recovery and Climate Experiment (GRACE) satellites is assimilated into a land surface model during 2003–2016 and used to initialize 6‐month hindcasts (i.e., forecasts of past events) during West Africa's wet seasons. We find that GRACE data assimilation (DA) generally increases groundwater and soil moisture storage in the region, resulting in increased evapotranspiration and reduced total runoff. Total runoff is particularly lower at the headwaters of the Niger River, positively impacting streamflow simulations and hindcast initializations. Compared to simulations without GRACE‐DA, hindcasts are notably improved at locations draining from large basin areas, in particular, over the Niger River basin, which is consistent with GRACE's coarse spatial resolution. The long memory of groundwater and deep soil moisture, two main TWS components updated by GRACE‐DA, is reflected in prolonged improvements in the streamflow hindcasts. Model accuracy at Niamey, Niger, the most populated city where streamflow observations are available, improved up to 33% during the flood season. These new findings directly contribute to ongoing developments in food security, flood potential forecast, and water‐related disaster warning systems for Africa.
One-pot construction of functionalized aziridines and maleimides via a novel pseudo-Knoevenagel cascade reaction
Authors: Lei Jie , Song Gui-Ting , He Liu-Jun , Luo Ya-Fei , Tang Dian-Yong , Lin Hui-Kuan , Frett Brendan , Li Hong-yu , Chen Zhong-Zhu , Xu Zhi-Gang
Published: January 2020

Synthesis of functionalized aziridines, aziridinyl succinimides and maleimides via an Ugi, novel pseudo-Knoevenagel, ring expansion cascade reaction in one-pot.
Metal-free regioselective C–H chalcogenylation of coumarins/(hetero)arenes at ambient temperature
Authors: Song Zengqiang , Ding Chaochao , Wang Shaoli , Dai Qian , Sheng Yaoguang , Zheng Zhilong , Liang Guang
Published: January 2020

A novel and practical method for the direct regioselective chalcogenylation of coumarins at the C3-postion and selenation of other (hetero)arenes has been achieved using PIFA as a promoter at room temperature.
Promoting photocatalytic hydrogen production by a core–shell CdS@MoOxphotocatalyst connected by an S–Mo “bridge”
Authors: Jiang Cankun , Zhang Lulu , Gao Fan , Huang Xueyan , Lei Rui , Ye Yun , Yuan Jie , Liu Ping
Published: January 2020

A novel CdS@MoOxcore–shell structure photocatalyst for photocatalytic hydrogen production, in which MoOxis used as an electron transport medium.
Linearly polarized lasing based on coupled perovskite microspheres
Authors: Zhou Beier , Zhong Yichi , Jiang Mingming , Zhang Jianhao , Dong Hongxing , Chen Linqi , Wu Hao , Xie Wei , Zhang Long
Published: January 2020

We achieve linearly polarized single-mode lasing based on the Vernier effect in perovskite microspheres.
Multi-interfacial plasmon coupling in multigap (Au/AgAu)@CdS core–shell hybrids for efficient photocatalytic hydrogen generation
Authors: Ma Liang , Chen You-Long , Yang Da-Jie , Li Hai-Xia , Ding Si-Jing , Xiong Lun , Qin Ping-Li , Chen Xiang-Bai
Published: January 2020

The hydrogen generation rates of multigap (Au/AgAu)@CdS hybrids have an exponential improvement compared with that of CdS as the number of nanogaps increases.
General synthesis of Pd–pm (pm = Ga, In, Sn, Pb, Bi) alloy nanosheet assemblies for advanced electrocatalysis
Authors: Shang Hongyuan , Xu Hui , Wang Cheng , Jin Liujun , Chen Chunyan , Zhou Guangyao , Wang Yuan , Du Yukou
Published: January 2020

A universal synthesis approach has been proposed to produce a series of well-defined Pd–pm (pm = Ga, In, Sn, Pb, Bi) alloy nanosheet assemblies.
The importance of the counter-cation in reductive rare-earth metal chemistry: 18-crown-6 instead of 2,2,2-cryptand allows isolation of [YII(NR2)3]1− and ynediolate and enediolate complexes from CO reactions
Authors: Ryan Austin J. , Ziller Joseph W. , Evans William J.
Published: January 2020

The use of 18-crown-6 (18-c-6) in place of 2.2.2-cryptand (crypt) in rare earth amide reduction reactions involving potassium has proven to be crucial in the synthesis of Ln(ii) complexes and isolation of their CO reduction products.
A high-performance functional phthalonitrile resin with a low melting point and a low dielectric constant
Authors: Wu Minjie , Xu Jianjun , Bai Shengnan , Chen Xinggang , Yu Xiaoyan , Naito Kimiyoshi , Zhang Zhenjiang , Zhang Qingxin
Published: January 2020

The fluorine-containing phthalonitrile PBDP has a low dielectric constant and an ultra-low water absorption, which is expected to be applied in electronic packaging.
Enhanced direct position determination using dynamic sensor array response
Authors: Eshkevari Ali , Sadough Seyed Mohammad Sajad
Published: January 2020

An improvement in localisation of co‐channel transmitters using direct position determination (DPD) is addressed. DPD techniques estimate the locations of signal emitters by finding the peaks of a spatial pseudo‐spectral‐function (PSF) within a definite area. Actually, different algorithms/beamformers such as Bartlett, minimum variance distortionless response (MVDR), and multiple signal classification (MUSIC) are distinguished by their PSFs. Mathematically, a PSF is a function of location through the array steering/pointing vector whose elements are the channel responses between any arbitrary point in the search area and each sensor antenna for a narrowband system model. Clearly, the amplitude and phase of each complex element of the pointing vector characterise the attenuation and delay of paths between search points and sensors, respectively. Classical DPD methods do not consider the dependency of attenuation on channel path length variation during area scanning, which consequently generates PSFs full of spurious peaks. The authors propose a more realistic channel model that remarks the free‐space‐path‐loss as a deterministic, path‐length‐dependent factor beside the stochastic ones such as fading; therefore, they call it dynamic sensor array response (DSAR). Simulations show that range dependency of DSAR can effectively enhance the performance of the DPD algorithm for MVDR and MUSIC beamformers.
Comment on ‘Criteria for robust finite‐time stabilisation of linear singular systems with interval time‐varying delay’
Authors: Wang Jianxin , Wu Hecheng
Published: January 2020

The objective of Muoi et al. 2017 is to give a delay‐dependent criterion for the considered linear singular time‐delay system to be finite‐time stabilisable with a state feedback controller, which is formulated in terms of linear matrix inequalities. However, this criterion is not correct, which is pointed out in this note.
Response to: ‘Comment on criteria for robust finite‐time stabilisation of linear singular systems with interval time‐varying delay’ by Wang and Wu
Authors: Muoi Nguyen H. , Ngoc Phat Vu , Niamsup Piyapong
Published: January 2020

We first give response to the comments pointed out by the authors of [1] (submitted), and then present some necessary corrections.
Transient response comparison of virtual oscillator controlled and droop controlled three‐phase inverters under load changes
Authors: Shi Zhan , Li Jiacheng , Nurdin Hendra I. , Fletcher John E.
Published: January 2020

This study compares two inverter control methods, virtual oscillator control (VOC) and droop control, in terms of time responses of a three‐phase single‐inverter system under a load step change. The analytical comparison is aided by small‐signal modelling. Two small‐signal VOC models are derived from the average VOC dynamics by approximating average power differently; two small‐signal droop control models using distinct filters are also assessed. By letting the two controllers have similar droop characteristics in steady state, participation analyses are performed to predict transient responses of the systems. The analyses are verified by simulations and experiments. This study presents a meticulous comparison between VOC and droop control in a three‐phase system. It is demonstrated that two types of linearized models produce similar transient responses in the output voltage and current amplitudes. VOC has a faster transient response in instantaneous frequency while the droop controller can have a transient response as fast as the VOC in the terminal voltage amplitude. This reveals that the VOC and droop controller can be designed to yield similar responses under a load disturbance. Comparing them in a stand‐alone system aids in understanding the control loop as a step towards understanding transient behavior in multiple source systems.
Fault ride‐through of grid‐connected THIPWM fired DCMLI‐based DFIG using parallel switched feedback‐controlled DVR
Authors: Hossam‐Eldin Ahmed A. , Negm Abdallah Emtethal , Elgamal Mohamed S. , AboRas Kareem M.
Published: January 2020

The proposed approach shows that the DCMLI systems generate a near sinusoidal voltage with reduced total harmonic distortion (THD). The power quality of the DFIG system is upgraded. A modified feedback control technique of DVR is pivotal to improve the capability of FRT in WECS based on DFIG like voltage sag, dip, swell, active and reactive power support with no tripping in the DFIG. It also achieves a flexible control solution for balanced and unbalanced fault conditions. The modified feedback DVR control overcomes any fault conditions that occur in the grid. The proposed system with DVR showed to be stable, very effective and verified. The main feature of using such combined control is verified through MATLAB/Simulink based simulation results of a 1.5 MW grid‐connected WECS based on DFIG. It has been verified under different operating conditions based on wind speed to test THD levels and under different fault conditions, to test ride‐through capabilities. The results showed good power quality performance and good FRT capability during various fault scenarios. The results are compared to the recently updated grid code standards, which make large wind farms to be treated, in the future, like conventional power plants.
Transactive energy coordination mechanism for community microgrids supplying multi‐dwelling residential apartments
Authors: Akter Most Nahida , Mahmud Md Apel , Haque Md Enamul , Oo Amanullah M.T.
Published: January 2020

A transactive energy coordination mechanism is proposed in this study where community microgrids are supplying power to multi‐dwelling residential apartments. The proposed transactive energy coordination mechanism coordinates the energy sharing among apartments based on the energy profile of the community microgrid where the excess energy is traded with non‐contributing apartments. The proposed coordination mechanism is embedded within an energy management controller which uses the energy profile and determines the valuation of energy. A choice factor along with the bound on electricity prices is also incorporated to calculate the bidding price and a double‐sided auction mechanism is considered for the bidding purpose. The utility maximisation approach is used to clear the market. Different scenarios based on the flexibility in the pricing strategy are considered to evaluate the performance of the proposed transactive energy coordination mechanism. The potential economic benefits of the proposed scheme are also analysed which clearly demonstrate that it is beneficial for all participants.
Robust distributed stochastic secondary control of microgrids with system and communication noises
Authors: Dehkordi Nima Mahdian , Nekoukar Vahab
Published: January 2020

This study proposes an advanced robust stochastic cooperative frequency/voltage restoration control considering the effects of both communication/system noises based on Kalman‐filtering theory for secondary control of islanded microgrids. Compared with existing ideal and noise‐resilient distributed methods, the proposed robust stochastic distributed secondary control method can achieve mean‐square synchronisation for voltage and frequency restoration of distributed generations (DGs) along with the real power sharing accuracy through a sparse communication network, even though both the system measurement and communication channels are susceptible to noise interferences and limited band‐width constraints. To this end, the graph theory, stochastic theory, and Kalman‐filtering theory are employed to estimate the states of each DG based on the information of noisy measurement, and then the estimated signals are sent to the neighbour DGs via a noisy communication environment. The main advantages of the proposed method are its ability to provide the quality of the estimate, low complexity, low computational burden, and working even though both the system and communication channels are susceptible to noise interferences and limited band‐width constraints. Finally, the simulation results in MATLAB/SimPowerSystems Toolbox show that the proposed method has better, robust, resilient, acceptable, and desirable performance compared with the recent and effective methods.
Zoning‐based candidate bus selection for dynamic VAR planning in power system towards voltage resilience
Authors: Chi Yuan , Xu Yan
Published: January 2020

Dynamic VAR planning for voltage stability enhancement is a challenging topic for power systems with a growing penetration level of wind power. As a critical step of VAR planning, candidate bus selection (CBS) can reduce the scale of the problem and improve the optimality of the planning decisions. This study proposes a new zoning‐based CBS method towards multiple voltage resilience indices. First, a set of resilience‐oriented metrics are proposed to comprehensively evaluate voltage performance in pre‐contingency and post‐contingency stages, considering the extent of the voltage deviation and voltage recovery time, as well as the post‐contingency steady‐state voltage profile. Then, a zoning‐based approach is developed based on fuzzy C‐means clustering and Morris screening to categorise buses into different zones with capacity sensitivity analysis. Finally, a comprehensive multi‐objective CBS scheme is proposed for voltage resilience enhancement. Simulation results show that, compared with conventional approaches, the method can achieve more voltage stability improvement with the fewer or the same number of candidate buses.
Frequency regulation of multiple asynchronous grids using adaptive droop in high‐voltage direct current system
Authors: Hassan Mehedi , Shah Rakibuzzaman , Hossain Jahangir
Published: January 2020

Frequency stability control in multiple asynchronous grids is a challenging and complex issue. An adaptive droop control strategy to improve the frequency regulation of asynchronous AC areas connected by a multi‐terminal DC grid is proposed here. The droop coefficients are adjusted to share the active power adaptively among multiple asynchronous AC grids based on the characteristics of frequency deviation and rate of change of frequency. This results in a cogent allocation of imbalance power in multiple asynchronous grids from the frequency variation perspective. The performance of the proposed scheme is evaluated in a modified multi‐machine power system using DIgSILENT Power Factory. Simulation results under significant frequency disturbances caused by credible contingencies are presented to demonstrate the effectiveness of the proposed approach. It is found that the proposed adaptive control ensures an excellent and robust frequency response under different operative conditions.
Metrics for assessing the resiliency in generation systems
Authors: Ghorbani Vahid , Sheisi Gholamhossein , Aghaei Jamshid
Published: January 2020

This study proposes new metrics for evaluating the resiliency index specific to the generation sector by considering the factors that affect the generation sector, such as location, capacity, number, and density of units and critical loads. These indexes can be useful for pre‐crisis action (PCA). By calculating and considering these indexes before any installation or expansion of the generation sector, the destructive effects of extreme events can be greatly reduced. In fact, the main purpose of this study is not to increase the level of the resiliency of the generation sector, but to only propose new indexes for calculating the resiliency. For this study, firstly, the factors that impact the resiliency of generation will be discussed, secondly, for each index, the calculation formula will be presented. Then, resiliency is calculated in the generation sector as a composite resiliency index, which is a combination of all indexes. For validation of these indexes, a criterion such as loss of critical load factor is introduced and case studies are performed based on the IEEE six‐bus and IEEE RTS‐24‐bus systems for different scenarios. The results show that the proposed indexes can effectively evaluate the resiliency of the generation sector.
Improved probabilistic load flow method based on D‐vine copulas and Latin hypercube sampling in distribution network with multiple wind generators
Authors: Huang Yueshan , Chen Shuheng , Chen Zhe , Hu Weihao , Huang Qi
Published: January 2020

In this study, a D‐vine copulas modelling based probabilistic load flow (PLF) computation method is proposed, which considers the dependence among multiple wind generators. Furthermore, this method is not restricted by the type of wind speed distribution, i.e. allow random variables to comply with any types of distribution model. Copula theory plays an important role on dependency modelling. However, when high‐dimensional correlation is taken into account, standard multivariate copula suffers from the problems of inflexible structure. Vine copula is flexible to build high‐dimensional dependence and able to construct complicated dependence structure by applying bivariate copulas. For marginal distributions of wind speed, non‐parametric model can provide a better estimation than those parametric models. An improved Latin hypercube sampling based Monte Carlo simulation method is utilised to solve PLF problems. A modified IEEE 33‐node distribution system is used to conduct the numerical experiments for the accuracy and efficiency verification of the proposed PLF method, under the MatlabR2016a platform. The simulation results verify the outstanding accuracy, efficiency and robustness of the proposed PLF method.
Use of demand response for voltage regulation in power distribution systems with flexible resources
Authors: Xie Qiangqiang , Hui Hongxun , Ding Yi , Ye Chengjin , Lin Zhenzhi , Wang Peng , Song Yonghua , Ji Ling , Chen Rong
Published: January 2020

In low‐voltage power distribution systems with high penetration of photovoltaics (PVs) generation and electric vehicles (EVs), the over‐voltage problem arises at times because of large PV generation, and under‐voltage problem also arises sometimes because of simultaneous charging of massive EVs. Over‐ and under‐voltage problems lead to more difficulties in achieving voltage regulation. Demand response (DR) is expected to be promising and cost‐effective in promoting smart grids, and hence, the utilisation of flexible resources (FRs) through DR can be helpful for distribution system voltage regulation. This study introduces a hierarchical control structure of a community energy management system (CEMS) and multiple sub‐CEMSs to apply an FR‐based two‐stage voltage regulation technique. In the first stage, i.e. the day‐ahead scheduling stage, each sub‐CEMS optimises the FRs’ schedules for minimising customers’ electricity cost and network voltage violation times. In the second stage, i.e. the real‐time operation stage, the voltage sensitivity‐based FRs’ shifting method is proposed to eliminate network voltage violations caused by errors of estimated day‐ahead data. The proposed models and methods are verified based on a realistic distribution system in Japan, where voltage violations, customer electricity cost and a number of on‐load tap changer tap operations are proved to be reduced.
Hierarchical and multi‐level demand response programme considering the flexibility of loads
Authors: Rajabi Firouzeh , Salami Abolfazl , Azimi Maryam
Published: January 2020

Demand response (DR) has a key role in reducing the peak load and avoiding the construction of unnecessary power plants. In this study, the new modified framework is presented to plan and control DR programmes (DRPs) with a novel mathematical model. The proposed hierarchical DRP is designed at three time levels to flatten the load curve, to balance between supply and demand, and to support system frequency. The proposed structure consists of three control loops with different response times from a fraction of a second to several hours for scheduling DR via defined control parameters in this programme. To minimise load variations and customer cost, the novel objective function based on weight matrices is presented. To optimally transfer loads, these matrices are weighted based on power market prices, load level, and flexibility of loads. Moreover, the demand flexibility index is used to take into account the uncertainty in the predicted load pattern and reduce errors of aggregation demand. The proposed programme has been implemented on a 20‐kV feeder to indicate its effective performance compared to hopping DR and centralised direct load control (DLC). The proposed mathematical model is verified by numerical results.
Experimental verification of monitoring techniques for metal‐oxide surge arrester
Authors: Dobric Goran , Stojkovic Zlatan , Stojanovic Zoran
Published: January 2020

Monitoring and diagnostics of metal‐oxide surge arresters (MOSAs) have been a research topic for decades. During these years, many monitoring and diagnostic methods have been developed. However, only a few studies perform a comparative analysis of these methods with respect to their performance in different operating conditions. This study briefly explains the most commonly analysed MOSA monitoring techniques and performs a comparative analysis of these techniques on an experimental basis, considering different operating conditions of the arrester. The experimental setting is made to simulate different operating conditions regarding operating voltage root mean square value, voltage harmonics, and temperature conditions. The results show the reliability of MOSA indicators in the analysed conditions, suggesting which indicators and methods should be used for the purpose of MOSA diagnostics.
Method to estimate sag frequency in doubly fed induction generator integrated power system based on adaptive kernel density estimation
Authors: Wang Ying , Tan Rui , Zheng Zi‐Xuan , Ni Fu‐Yao , Xiao Xian‐Yong
Published: January 2020

Voltage sag frequency estimation is necessary for understanding the voltage sag severity in power system and offering full information for the interested parties to mitigate voltage sag. The high penetration of wind power in the power system and the uncertainty of the fault distribution raise new challenges to accurate voltage sag frequency estimation. This study presents a systematic voltage sag frequency estimation method, considering the fault distribution density, fault ride‐through (FRT) process of wind turbines during voltage sag and the interval characteristic of voltage sag frequency. First, this study proposes a fault distribution estimation model based on adaptive kernel density. Second, this study proposes a method for calculating the residual voltage and duration of voltage sag during FRT and combines the common distance protection action to analyse the effect on voltage sag by FRT process of wind turbines. Lastly, this study proposes an interval‐valued voltage sag estimation method considering the interval characteristics of fault rate in the power system. IEEE 30‐bus test system is used to verify the proposed method, the estimation results show better performance of the proposed method compared with the typical estimation methods.
Inhomogeneous morphological PDEs for robust and adaptive image shock filters
Authors: Diop El Hadji S. , Angulo Jesùs
Published: January 2020

Classical morphological filters suffer from well performing in a noisy environment, and intrinsic image structures are not taken into account. The authors propose here an alternative to overcome such weaknesses, by properly using robust shock filters and inhomogeneity. Thus, they obtain multiscale morphological operators by using image edge functions as local weights in inhomogeneous Hamiltonians in classical multiscale dilations/erosions formulated with partial differential equations (PDEs). They provide the equivalent sup–inf‐based formulations, and derive sharpening/enhancement methods. In addition, they establish the PDE associated with the asymptotical iterations of the proposed robust and adaptive filters. The good behaviours of the proposed sup–inf and PDE‐based methods are illustrated on synthetic, greyscale, and colour images; results are analysed both qualitatively and quantitatively.
Mitigating errors of predicted delays of a train at neighbouring stops
Authors: Zhang Lukai , Feng Xuesong , Ding Chuanchen , Liu Yi
Published: January 2020

Delay prediction is significant for the well‐organised operation of trains. Meanwhile, the accurate prediction is interfered by comprehensive factors in practice, hence there are always quite a few predicted errors due to cascading effect in operation. This study newly proposes a method based on state‐space equations to mitigate errors of predicted delays of a train at neighbouring stops. A linear quadratic regulator for reducing errors is developed from modern control theory. Moreover, necessary derivation and proof processes are made to support the method. An artificial fish swarm algorithm is designed to determine necessary parameters of the regulator, and the corresponding simulation is achieved by the SIMULINK architecture. The new method is able to be an effective reference for theoretical innovation and practical application in the operation of railway systems.