bluuebunny/crossref_metadata_2025 huggingface dataset:
Engineering crack tortuosity in printed polymer–polymer composites through ordered pores
Authors: Gockowski Luke F. , Dolinski Neil D. , Chavez Roberto , Cohen Noy , Eisenreich Fabian , Hecht Stefan , McMeeking Robert M. , Hawker Craig J. , Valentine Megan T.
Published: April 2020

A recently developed multimaterial printing approach, solution mask liquid lithography, is used to produce porous polymer–polymer composites inspired by hierarchical natural structures that exhibit significant crack deflection.
Identifying the targets and functions of N-linked protein glycosylation in Campylobacter jejuni
Authors: Cain Joel A. , Dale Ashleigh L. , Sumer-Bayraktar Zeynep , Solis Nestor , Cordwell Stuart J.
Published: April 2020

Virulence of Campylobacter jejuni is dependent on the ability to glycosylate membrane-associated proteins.
The study of levels from redox-active elements in cerebrospinal fluid of amyotrophic lateral sclerosis patients carrying disease-related gene mutations shows potential copper dyshomeostasis
Authors: Violi Federica , Solovyev Nikolay , Vinceti Marco , Mandrioli Jessica , Lucio Marianna , Michalke Bernhard
Published: April 2020

Amyotrophic lateral sclerosis is a progressive neurodegenerative disease characterized by a loss of function of motor neurons. The etiology of this disorder is still largely unknown. Gene-environment interaction arises as a possible key factor in the development of amyotrophic lateral sclerosis. We assessed the levels of trace metals, copper (Cu), iron (Fe), and manganese (Mn), of 9 amyotrophic lateral sclerosis cases and 40 controls by measuring their content in cerebrospinal fluid. The following trace element species were quantified using ion chromatography-inductively coupled plasma mass spectrometry: univalent copper (Cu-I), divalent Cu (Cu-II), divalent Fe (Fe-II), trivalent Fe (Fe-III), divalent Mn (Mn-II), trivalent Mn (Mn-III), and also unidentified Mn species (Mn-unknown) were present in some samples. When computing the relative risks for amyotrophic lateral sclerosis through an unconditional logistic regression model, we observed a weak and imprecise positive association for iron (Fe III, adjusted odds ratio 1.48, 95% CI 0.46–4.76) and manganese (total-Mn and Mn-II; adjusted odds ratio 1.11, 95% CI 0.74–1.67, and 1.13, 95% CI 0.79–1.61, respectively). Increased risk for copper was found both in the crude analysis (odds ratio 1.14, 95% CI 0.99–1.31) and in multivariable analysis after adjusting for sex, age, and year of storage (1.09, 95% CI 0.90–1.32). Our results suggest a possible positive association between Cu and genetic amyotrophic lateral sclerosis, while they give little indication of involvement of Fe and Mn in disease, though some correlations found also for these elements deserve further investigation.
Quantitative optical microspectroscopy, electron microscopy, and modelling of individual silver nanocubes reveal surface compositional changes at the nanoscale
Authors: Wang Yisu , Zilli Attilio , Sztranyovszky Zoltan , Langbein Wolfgang , Borri Paola
Published: April 2020

A method and analysis pipeline correlating electron microscopy with quantitative micro-spectroscopy of particles immersed in different media is presented. Comparing measured and simulated cross sections reveals a tarnish layer on silver nanocubes.
Perspectives from nearly five decades of total synthesis of natural products and their analogues for biology and medicine
Authors: Nicolaou K. C. , Rigol Stephan
Published: April 2020

This review article summarises a series of total syntheses of natural and designed molecules primarily for biology and medicine. Aspects of new synthetic strategies and methods and optimisation of biological properties are emphasised.
Dehydration reactions in polyfunctional natural products
Authors: Hjerrild Per , Tørring Thomas , Poulsen Thomas B.
Published: April 2020

Here, we review methods for chemical dehydration of alcohols to alkenes and discuss the potential of late-stage functionalization by direct, site- and chemo-selective dehydration of complex molecular substrates.
Engineering macrophage-derived exosomes for targeted chemotherapy of triple-negative breast cancer
Authors: Li Sha , Wu Yijing , Ding Fei , Yang Jiapei , Li Jing , Gao Xihui , Zhang Chuan , Feng Jing
Published: April 2020

A macrophage exosome coated nanoplatform for targeted chemotherapy of triple-negative breast cancer.
Elucidating the relationship between nanoparticle morphology, nuclear/magnetic texture and magnetic performance of sintered SrFe12O19 magnets
Authors: Saura-Múzquiz Matilde , Eikeland Anna Zink , Stingaciu Marian , Andersen Henrik Lyder , Granados-Miralles Cecilia , Avdeev Maxim , Luzin Vladimir , Christensen Mogens
Published: April 2020

The relationship between nanoparticle morphology, self-induced atomic/magnetic texture and magnetic properties of high-performance hexaferrite magnets is elucidated using neutron/X-ray pole figure analysis and neutron/synchrotron powder diffraction.
N-Hydroxy peptides: solid-phase synthesis and β-sheet propensity
Authors: Sarnowski Matthew P. , Del Valle Juan R.
Published: April 2020

Backbone amide hydroxylation of peptide strands enhances β-hairpin folding.
Sequential and alternating RAFT single unit monomer insertion: model trimers as the guide for discrete oligomer synthesis
Authors: Liu Ruizhe , Zhang Lei , Huang Zixuan , Xu Jiangtao
Published: April 2020

A complete set of model trimers and their synthetic kinetics are established to guide the synthesis of diverse sequence-defined polymers.
Ag nanoparticle embedded Cu nanoporous hybrid arrays for the selective electrocatalytic reduction of CO2 towards ethylene
Authors: Hou Liang , Han Jianyu , Wang Chong , Zhang Yuwei , Wang Yuanbin , Bai Zhiming , Gu Yousong , Gao Yan , Yan Xiaoqin
Published: April 2020

The Ag/Cu composites present excellent catalytic activity for the reduction of CO2 to C2H4, and exhibit a maximum Faraday Efficiency 41.3%.
Intentional modification of the optical spectral response and relative sensitivity of luminescent thermometers based on Fe3+,Cr3+,Nd3+ co-doped garnet nanocrystals by crystal field strength optimization
Authors: Kniec K. , Ledwa K. , Maciejewska K. , Marciniak L.
Published: April 2020

The relative sensitivity and usable temperature range of Fe3+,Cr3+-based luminescent thermometers can be tuned by modification of the crystal field strength.
Tricarabrols A–C, three anti-inflammatory sesquiterpene lactone trimers featuring a methylene-tethered linkage from Carpesium faberi
Authors: Yuan Jie , Wen Xuelan , Ke Chang-Qiang , Zhang Tian , Lin Ligen , Yao Sheng , Goodpaster Jason D. , Tang Chunping , Ye Yang
Published: April 2020

Three anti-inflammatory trimeric compounds constructed from carabrol-type sesquiterpenoids through a methylene-tethered linkage were characterized from Carpesium faberi.
Synthesis and properties of hypervalent electron-rich pentacoordinate nitrogen compounds
Authors: Yan Chenting , Takeshita Masato , Nakatsuji Jun-ya , Kurosaki Akihiro , Sato Kaoko , Shang Rong , Nakamoto Masaaki , Yamamoto Yohsuke , Adachi Yohei , Furukawa Ko , Kishi Ryohei , Nakano Masayoshi
Published: April 2020

Structural characterization of hypervalent electron-rich pentacoordinate nitrogen species has long been a synthetic challenge. Here we report the first nitrogen cationic radical (11-N-5) species featuring a weak hypervalent 3c-5e interaction.
High-efficiency dynamic sensing of biothiols in cancer cells with a fluorescent β-cyclodextrin supramolecular assembly
Authors: Liu Zhixue , Zhou Weilei , Li Jingjing , Zhang Haoyang , Dai Xianyin , Liu Yaohua , Liu Yu
Published: April 2020

A unique fluorescent supramolecular assembly was constructed from coumarin-modified β-cyclodextrin and an adamantane-modified cyclic arginine–glycine–aspartate peptide for high-efficiency real-time monitoring of biothiols in cancer cells.
Polymorphism of asymmetric catalysts based on amphiphilic lipopeptides in solution
Authors: Pelin Juliane N. B. D. , Edwards-Gayle Charlotte J. C. , Aguilar Andrea M. , Kaur Amanpreet , Hamley Ian W. , Alves Wendel A.
Published: April 2020

The self-assembly of model [P]RWG lipopeptides (P: l-proline, R: l-arginine, W: l-tryptophan, G: l-glycine), containing one or two aliphatic octadecyl (C18) chains in water and cyclohexanone/water solutions was examined. The enantiomeric selectivity was found to be related to the assembly of catalyst molecules.
Robust pure copper framework by extrusion 3D printing for advanced lithium metal anodes
Authors: Lim Gwendolyn J. H. , Lyu Zhiyang , Zhang Xin , Koh J. Justin , Zhang Yu , He Chaobin , Adams Stefan , Wang John , Ding Jun
Published: April 2020

A novel robust and self-standing 3D-printed pure copper framework (3DP-Cu) is developed as a Li host and current collector. 3D-printing allows microchannels to be deliberately incorporated, benefiting both mechanical and electrochemical performances.
Quasi-quantum dot-induced stabilization of α-CsPbI3perovskite for high-efficiency solar cells
Authors: Liu Cheng , Yang Yi , Liu Xin , Ding Yong , Arain Zulqarnain , Li Xinye , Li Yuanlong , Zhou Zian , Dai Songyuan , Nazeeruddin Mohammad Khaja
Published: April 2020

Quasi-quantum dots α-CsPbI3films arein situprepared by using a new ligand with ultralow contents. By increasing the film hydrophobicity and surface Gibbs energy, the device with efficiency of 13.5% keeps stable under ambient condition for 30 days.
Achieving a 2.7 V aqueous hybrid supercapacitor by the pH-regulation of electrolyte
Authors: Su Lijun , Zhang Qingnuan , Wang Yue , Meng Jianing , Xu Yongtai , Liu Lingyang , Yan Xingbin
Published: April 2020

We present an effective electrolyte pH-regulation strategy for cation-intercalated manganese oxides to extend the voltage window of aqueous supercapacitors.
Intense pulsed light-based synthesis of hybrid TiO2–SnO2/MWCNT doped Cu-BTC for room temperature ammonia sensing
Authors: Wong Danny , Abuzalat Osama , Mostafa Sherif , Park Simon S. , Kim Seonghwan
Published: April 2020

Fabrication of the hybrid TiO2–SnO2/MWCNTs@Cu-BTC film by IPL onto a quartz crystal microbalance for ammonia sensing at room temperature.
Asymmetric organic semiconductors for high performance single crystalline field-effect transistors with low activation energy
Authors: Qiu Fei , Dong Yicai , Liu Jie , Sun Yanan , Geng Hua , Zhang Hantang , Zhu Danlei , Shi Xiaosong , Liu Jianghong , Zhang Jing , Ai Shiyun , Jiang Lang
Published: April 2020

We synthesized three asymmetric anthracene derivatives, in which 2-phvA shows a high field-effect mobility of 10 cm2 V−1 s−1. This work demonstrates the potential advantages of asymmetric structures for high-performance organic semiconductors.
Highly efficient fluorescence/phosphorescence hybrid white organic light-emitting devices based on a bipolar blue emitter to precisely control charges and excitons
Authors: Chen Yuwen , Zhu Jieji , Wu Yibing , Yao Jingwen , Yang Dezhi , Qiao Xianfeng , Dai Yanfeng , Tong Qingxiao , Ma Dongge
Published: April 2020

Highly efficient fluorescence/phosphorescence hybrid WOLEDs have been realized by employing a new efficient blue fluorescent material.
Mesenchymal stem cell-derived secretomes for therapeutic potential of premature infant diseases
Authors: Wang Yu , Long Wei , Cao Yan , Li Jingyun , You Lianghui , Fan Yuru
Published: April 2020

Preterm birth is a complex syndrome and remains a substantial public health problem globally. Its common complications include periventricular leukomalacia (PVL), bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC) and retinopathy of prematurity (ROP). Despite great advances in the comprehension of the pathogenesis and improvements in neonatal intensive care and associated medicine, preterm birth-related diseases remain essentially without adequate treatment and can lead to high morbidity and mortality. The therapeutic potential of mesenchymal stem/stromal cells (MSCs) appears promising as evidenced by their efficacy in preclinical models of pathologies relevant to premature infant complications. MSC-based therapeutic efficacy is closely associated with MSC secretomes and a subsequent paracrine action response to tissue injuries, which are complex and abundant in response to the local microenvironment. In the current review, we summarize the paracrine mechanisms of MSC secretomes underlying diverse preterm birth-related diseases, including PVL, BPD, NEC and ROP, are summarized, and focus is placed on MSC-conditioned media (CM) and MSC-derived extracellular vesicles (EVs) as key mediators of modulatory action, thereby providing new insights for future therapies in newborn medicine.
Post-translational modifications and stress adaptation: the paradigm of FKBP51
Authors: Rein Theo
Published: April 2020

Adaptation to stress is a fundamental requirement to cope with changing environmental conditions that pose a threat to the homeostasis of cells and organisms. Post-translational modifications (PTMs) of proteins represent a possibility to quickly produce proteins with new features demanding relatively little cellular resources. FK506 binding protein (FKBP) 51 is a pivotal stress protein that is involved in the regulation of several executers of PTMs. This mini-review discusses the role of FKBP51 in the function of proteins responsible for setting the phosphorylation, ubiquitination and lipidation of other proteins. Examples include the kinases Akt1, CDK5 and GSK3β, the phosphatases calcineurin, PP2A and PHLPP, and the ubiquitin E3-ligase SKP2. The impact of FKBP51 on PTMs of signal transduction proteins significantly extends the functional versatility of this protein. As a stress-induced protein, FKBP51 uses re-setting of PTMs to relay the effect of stress on various signaling pathways.
Multi‐rate sampled‐data control of switched affine systems
Authors: Wu Feiyue , Qu Xuehao , Li Chunyang , Lian Jie , Xu Lingli
Published: April 2020

This study considers the practical stabilisation of switched affine systems under the multi‐rate sampled‐data switching control. In order to depict the sampled value of all state components, a sensing block composed of several sensors with asynchronous uncertain non‐uniform sampling intervals is applied. On the basis of the sampled‐data value, a new class of functionals is developed, which is composed of a Lyapunov–Krasovskii functional and a looped function. Practical stabilisation conditions are presented for the switched affine system by means of a switching law. Two examples are provided to demonstrate the effectiveness and feasibility of the proposed results.
Distributed backstepping based control of multiple UAV formation flight subject to time delays
Authors: Kartal Yusuf , Subbarao Kamesh , Gans Nicholas R. , Dogan Atilla , Lewis Frank
Published: April 2020

In this study, the authors propose a backstepping‐based, distributed formation control method that is stable independent of time delays in communication among multiple unmanned aerial vehicles (UAVs). Centralised formation control of UAVs requires each agent to maintain a separation distance from other agents, which burdens the communication network of the UAVs. To overcome this problem, the authors consider a distributed control scheme wherein each agent updates its attitude and position based on the state information gathered through its neighbours. Instead of directly controlling the thrust generated by the propellers, they partition the mathematical model of the UAV into two subsystems, a linear attitude control loop and a non‐linear position control loop. A backstepping‐based outer position controller is then designed that interfaces seamlessly with the inner attitude controller of the cascaded control system. The closed‐loop stability is established using a rigorous Lyapunov–Krasovskii analysis under the influence of distributed network time delays. Using the directed graph topology and a distributed backstepping structure, it is shown that the stability criterion is delay‐independent. The proposed control algorithms are verified in simulation and then implemented in hardware, and actual flight test experiments prove the validity of these algorithms.
Protection coordination for networked microgrids using single and dual setting overcurrent relays
Authors: Alam Mahamad Nabab , Gokaraju Ramakrishna , Chakrabarti Saikat
Published: April 2020

The operation of multiple microgrids (MGs) with distribution system enhances reliability and resiliency of the power supply significantly by enabling high penetration of locally available distributed energy resources (DERs). However, there are several issues in the proper operation of multiple MGs that need to be addressed. Providing proper protection coordination is one of the most important issues in the coordinated operation of networked MGs (NMGs). In this study, an efficient protection coordination scheme for NMGs is proposed by utilising the commonly used numerical directional overcurrent relays (DOCRs) with single and dual settings. Issues related to the operation of NMGs such as the change in network topology, connection status of the point of common coupling and low voltage fault ride through of DERs have been considered. The protection coordination problem has been formulated as an optimisation problem and solved using the interior point method. The proposed protection coordination scheme of NMGs has been tested on the 69‐bus radial distribution system with the integration of three MGs, which is not reported in earlier literature. The suitability and effectiveness of the proposed DOCRs coordination scheme have been demonstrated.
Procurement of electrical energy and operating reserve ancillary services in wind incorporated deregulated system considering demand response
Authors: Sharma Akanksha , Jain Sanjay K.
Published: April 2020

This study presents the procurement of electrical energy and operating reserve ancillary services (ORASs) by the simultaneous clearing of the wind integrated power market under the pool‐based deregulated environment. This investigation is important due to the intermittent output of wind generators, which is a serious concern for medium and high wind penetration and requirement of high operating reserves for maintaining the security of such systems. The market model is presented for the clearing of energy and ORAS market, where both thermal generators and demand response offers supply the reserves. This model is analysed for energy and spinning reserve (ESR) cost minimisation, emission minimisation, and co‐optimisation of ESR cost and emission. The non‐dominated sorting multi‐objective gravitational search algorithm is employed to obtain Pareto optimal solutions. The efficacy of the presented method is investigated on IEEE 30‐bus, IEEE 118‐bus, and IEEE 300‐bus test systems for different levels of wind uncertainty. The results are compared with multi‐objective particle swarm optimisation.
Tight convex relaxation for TEP problem: a multiparametric disaggregation approach
Authors: Goodarzi Shahin , Gitizadeh Mohsen , Abbasi Ali Reza , Lehtonen Matti
Published: April 2020

In recent years, there has been an increasing interest in using AC power flow equations for the transmission expansion planning (TEP) studies. The AC power flow equations are quadratic and hence the TEP problem can be formulated as a mixed‐integer quadratically constrained programme. Therefore, the complexity of the TEP problem lies in the non‐convexity of AC power flow equations in which the global optimal solution is not guaranteed to be found. This study aims at proposing a tight convex relaxation for the TEP problem. In this context, first, the TEP problem is formulated as a mixed‐integer bilinear problem by representing the complex bus voltage in its rectangular coordinates. Second, the multiparametric disaggregation technique (MDT) and piecewise McCormick relaxation are employed to generate a mixed‐integer linear relaxation. MDT is based on the discretisation of the domain of one of the variables in every bilinear term. The method presented is much more precise compared with the DC or other linearisation approaches, while the optimal solution is of high quality. The results of the case studies show the tractability and exactness of the proposed model as well as its superiority over the state‐of‐the‐art schemes.
PIDF(1+FOD) controller for load frequency control with SSSC and AC–DC tie‐line in deregulated environment
Authors: Prakash Abhineet , Kumar Kundan , Parida Sanjoy Kumar
Published: April 2020

In this study, a maiden application of cascade proportional–integral–derivative with filter (PIDF) and one plus fractional‐order derivative (1+FOD), i.e. PIDF(1+FOD) controller is proposed for the load frequency control mechanism. The main purpose of the cascade and fractional order controller is to increase the degree of freedom and reject the disturbances faster. A novel attempt has also been made to model a static synchronous series compensator (SSSC) with AC tie‐line and HVDC tie‐line. Here SSSC and HVDC tie‐line are used to regulate and increase the power transfer capabilities between interconnected areas. Furthermore stored energy in the HVDC tie‐line is utilised to improve the system dynamics by inertia emulation control strategy. An evolutionary salp swarm algorithm‐based optimisation technique is adopted to optimise control parameters. The performance of the proposed controller is tested on a two‐area hydro‐thermal interconnected power system in deregulated environment. First, the effectiveness AC–DC‐SSSC tie line is shown over AC‐SSSC and alone AC tie‐line with proposed PIDF(1+FOD) controller followed by the supremacy of proposed PIDF(1+FOD) over classical controllers. Finally, sensitivity is analysed by variation in system parameters, which shows the robustness of the proposed controller.
Bi‐layer portfolio selection model for electricity retailers based on behavioural portfolio theory under quota obligation of RPS
Authors: Jiang Yicheng , Liu Shengyuan , Yang Li , Lin Zhenzhi , Ding Yi , He Chuan , Li Jing , Wang Kai
Published: April 2020

With the development of renewable energy market, Renewable Portfolio Standard (RPS) has become the targeted renewable energy incentive mechanism in China and it is under a government's long‐term plan that RPS overtakes feed‐in tariff gradually in recent years. Given this background, the decision‐making model of electricity retailers to accomplish the obligation under RPS is constructed as a bi‐layer portfolio selection model. In the inner‐layer, both capital allocation of the retailers to purchase various kinds of renewable energy capacity as well as RECs are optimised. In the outer‐layer, the capital investment portfolio of each risky and risk‐free strategy is determined based on the Behavioural Portfolio Theory, with different mental accounts (MAs) with different aspiration points and threshold levels built to describe the investor philosophy of retailers during the decision‐making process. The simulation results of a provincial electricity market in China demonstrate that the presented model can effectively assist electricity retailers in making their capital investment strategies under RPS with relevant market factors. In addition, the proposed model provides insights for policy makers to set key parameters involving the design of RPS by analysing behaviours of retailers, including required quota ratio and value of fines.
Critical node identification in active distribution network using resilience and risk theory
Authors: Zhang Wen , Liu Ke‐yan , Sheng Wanxing , Du Songhuai , Jia Dongli
Published: April 2020

Accurately identifying the key links in active distribution network (ADN) that affect the system's safety and stability is of great significance to improve the efficiency of operation and maintenance and risk early warning for distribution network (DN). In this study, the node resilience (NR) is first proposed as an indicator for structural stability identification of DN. Then, a critical node identification method considering the security, economy and structure stability in ADN is proposed, which uses the NR, the utility risks of branch load change, node voltage deviation and line loss variation as the identification indicators. Also, combining with subjective experience and objective data, the comprehensive evaluation method of critical nodes is improved, and the multilevel and multidimensional evaluation model of critical nodes is constructed. Furthermore, the time sequence of load change and photovoltaic output is considered. Finally, the rationality and effectiveness of the proposed method are proved by taking IEEE 33‐bus system and an actual ADN as examples.
Modelling and analysis of radial distribution network with high penetration of renewable energy considering the time series characteristics
Authors: Liu Jiayan , Zhou Yang , Li Yong , Lin Gang , Zu Wenjing , Cao Yijia , Qiao Xuebo , bo Sun Chong , Cao Yi , Rehtanz Christian
Published: April 2020

Power distribution networks are in a transformation active distribution networks with distributed energy resources. However, the widely adopted distribution test networks were established many years ago, which are untimely and cannot reflect the characteristics of high penetration renewable energy. Therefore, in this study, a distribution network with high penetration renewable energy is established based on the real data of a renewable‐energy‐rich radial rural distribution network in China. The proposed radial distribution network includes three types of loads and two types of renewable energy distributed generations. The evaluation indexes are designed to assess the proposed system and compare with the existing distribution networks. In addition, the topical high/low voltage problem of distribution network caused by high penetration of renewables is discussed. Furthermore, based on the measured time series characteristics of load and renewable resources, the effectiveness of the proposed system is validated by power flow analysis and dynamic characteristic criterion.
Coordinated scheme for expansion planning of distribution networks: a bilevel game approach
Authors: Akbari Tohid , Moghaddam Saeed Zolfaghari
Published: April 2020

The expansion planning of a distribution network (DN) is studied separately and independently from the behaviour of the transmission network (TN) as well as other DNs. However, DNs are being converted from passive to active mode by extensively integrating distributed generations (DGs) into them. Hence, an uncoordinated expansion planning may lead to redundant investment cost and suboptimal solutions. Accordingly, the main motivation of this study is to propose a coordinated expansion scheme among distribution companies (DISCOs). In doing so, a novel bilevel game‐based framework is presented to coordinate the decisions of DISCOs for distribution expansion planning problem. Primal–dual formulation is used to convert the bilevel problem into a single level one resulting in a discretely‐constrained generalised Nash equilibrium problem. The generalised Nash equilibrium problem is further formulated as a mixed‐integer linear program using Karush–Kuhn–Tucker conditions. The methodology proposed is applied to the IEEE 24‐bus RTS with several 24‐bus DNs. The results show that ignoring the action of other DISCOs may lead to the over‐ or under‐investment in DG sector which consequently decreases the DISCOs’ profit. The results also show that congestion in transmission lines can considerably affect the strategic decisions of DISCOs on DG investment.
Extended Park's vector method in early inter‐turn short circuit fault detection for the stator windings of offshore wind doubly‐fed induction generators
Authors: Wei Shurong , Zhang Xin , Xu Yao , Fu Yang , Ren Zixu , Li Fangxing
Published: April 2020

To avoid dramatic economic losses and unrecoverable failures in offshore wind farms, it is necessary to accurately detect faults at the early stage of doubly‐fed induction generators. The new extended Park's vector method is proposed in the study. The amplitude of the twice fundamental frequency component of the square of the Park's vector module is selected as the new fault feature to realise the early fault detection. The relationship between the extended Park's vector method and negative sequence current of the stator is also analysed in the study. The Fryze–Buchholz–Dpenbrock algorithm and the non‐linear least squares method are applied to estimate the mathematic relationship among unbalanced stator voltage, load change and the negative sequence current of the stator. The experiments were conducted and the results showed that the proposed method is robust to the effects of the unbalanced stator voltage and load change. Therefore, the proposed method can accurately detect faults at the early stage with high sensitivity and reliability.
Frequency control of droop‐based low‐voltage microgrids with cobweb network topologies
Authors: Yu Chang , Zhou Hong , Lu Xiaoqing
Published: April 2020

When distributed generation (DG) technologies are implemented in an islanded low‐voltage microgrid (LVMG), the topological architecture directly affects the frequency synchronisability. Especially in cases of high DG penetration, the synchronisability of existing traditional topological architectures for LVMGs is very limited. However, a cobweb network topology, which combines the characteristics of several traditional topological architectures, has become a novel alternative for LVMGs. In this context, a compact criterion related to the Moore–Penrose inverse of the incidence matrix for the synchronisability of an LVMG is derived. Then, based on a linear transformation and Moore–Penrose inverse theory, a comparative analysis of the synchronisability of LVMG systems with different topological architectures is presented, the results of which indicate that the synchronisability can be significantly enhanced in a cobweb network topology and that the Braess paradox can also be effectively avoided during the corresponding topological transformation. The effectiveness of the proposed synchronisation criterion is validated based on the Iceland power network, modelled as a cobweb‐based LVMG with large‐scale DG integration, which exhibits excellent sychronisability.
Robustness‐oriented P‐band phased array radar front‐end with high phase and gain resolution in 0.18 BiCMOS
Authors: Wu Wen‐Guang , Fang Yun , Yu Xiao‐Peng , Sui Wen‐Quan , Chen Jer‐Ming , Yeo Kiat Seng
Published: April 2020

In this study, the authors present a P‐band phased array front‐end for radar applications, implemented using a 0.18  SiGe BiCMOS process, thereby enhancing robustness over process‐voltage‐temperature (PVT) variations. It comprises a low noise amplifier, 6‐bit attenuator, 6‐bit phase shifter, power amplifier, T‐R switches as well as control circuits. As the key here is to achieve high resolutions in both gain and phase controls, the 6‐bit attenuator and 6‐bit phase shifter are optimised by cascading unit cells with different topologies, hence ensuring a good balance between accuracy, silicon area and robustness. Temperature compensation techniques are also used in the low noise amplifier and power amplifier so that the circuit works robustly against PVT variations. Fabricated using TowerJazz 0.18  SiGe BiCMOS technology, the prototype front‐end occupies a chip area of , including bonding pads and test buffers. It performs with a receiver (RX) gain of 12 dB, a 3 dB noise figure, and a transmitter (TX) gain of 29 dB, while consuming 60 mW (RX mode) and 600 mW (TX mode) from a 3.3 V supply voltage. The chip is also measured in extreme conditions (e.g. temperatures exceeding ) to ensure robust operation and is suitable for low‐cost phased array systems.
Dual‐broadband highly efficient reflective multi‐polarisation converter based on multi‐order plasmon resonant metasurface
Authors: Zheng Qi , Guo Chenjiang , Vandenbosch Guy A.E. , Yuan Pengliang , Ding Jun
Published: April 2020

In this study, a dual‐broadband reflective polarisation converter with high efficiency for both linear‐to‐linear and linear‐to‐circular polarisations based on a metasurface is proposed. Owing to the characteristics of strong anisotropy and multi‐order plasmon resonances, the proposed polarisation converter can rotate an y/x polarised electromagnetic wave to its cross‐polarised (x/y) direction in the lower frequency band of 7.74–14.44 GHz (a fractional bandwidth of 60.4%) with over 0.9 polarisation conversion ratio. Besides, the proposed structure can also convert a linearly polarised incident wave to a circularly polarised one after reflection in the higher frequency band of 14.95–17.35 GHz (a fractional bandwidth of 14.9%). The performance in the two bands can be controlled separately by altering the proper parameters of the structure. Numerical analysis is used to predict the polarisation states of the proposed polarisation converter. Moreover, the physical mechanism of multiple resonances is discussed based on surface current distributions. A prototype of the polarisation converter is fabricated and measured. A reasonable agreement between the experiments and simulations is obtained. The design has a simple and scalable geometry, and is a good candidate for polarisation control devices in microwave, terahertz and optical frequency regions.
Turbo‐coded secure and reliable quantum teleportation
Authors: Cane Rosie , Xie Wanwan , Ng Soon Xin
Published: April 2020

Quantum teleportation allows an unknown arbitrary quantum state to be transmitted between two separate locations. To achieve this, the system requires both classical and quantum channels, for communicating two classical bits and an entangled quantum bit from the transmitter to the receiver. It is commonly assumed that both channels are error‐free, however, under realistic conditions, this is unlikely to be the case. This study proposed and investigated a secure and reliable quantum teleportation scheme when both classical and quantum channels exhibit errors. It was found that the security and reliability of the teleportation could be improved when powerful turbo codes are employed.
Chaotic sine–cosine algorithm for chance‐constrained economic emission dispatch problem including wind energy
Authors: Guesmi Tawfik , Farah Anouar , Marouani Ismail , Alshammari Badr , Abdallah Hsan Hadj
Published: April 2020

One of the most effective approaches to reduce carbon emissions is the integration of renewable energy sources into electrical power networks. Currently, wind turbines are the fastest growing among all renewable sources. With the integration of wind farms into electrical grids, the economic emission dispatch (EED) problem is becoming more complicated due to the stochastic availability of wind energy. In this study, a new approach is proposed to solve the EED problem incorporating wind farms. The problem is formulated as a chance‐constrained problem to deal with the stochastic characteristic of wind power. A novel chaotic sine–cosine algorithm (CSCA) is proposed to provide the optimal generation schedule to minimise simultaneously the generation cost and emission. Some weakness has been encountered in exploitation and exploration capabilities in standard sine cosine algorithm (SCA). Hence, the chaos is integrated into the original SCA to improve its performance. In addition, a new mutation strategy is added to the SCA. In this study, the new algorithm is based on three mutually exclusive equations. The new technique is applied on the 69‐bus ten‐unit and 40‐unit test systems with and without wind energy. The results performed by CSCA are compared with those generated by other recent techniques.
Wind turbine power coefficient models based on neural networks and polynomial fitting
Authors: Carpintero‐Renteria Miguel , Santos‐Martin David , Lent Andrew , Ramos Carlos
Published: April 2020

The power coefficient parameter represents the aerodynamic wind turbine efficiency. Since the 1980s, several equations have been used in the literature to study the power coefficient as a function of the tip speed ratio and the pitch angle. In this study, these equations are reviewed and compared. A corrected blade element momentum algorithm is used to generate three sets of data representing different ranges of wind turbines, going from 2 to 10 MW. With this information, two power coefficient models are proposed and shared. One model is based on a polynomial fitting, whereas the other is based on neural network techniques. Both were trained with the blade element momentum model output data and showed good behaviour for all operating ranges. In the results, compared to all the algorithms found in the literature, the proposed models reduced the power coefficient error by at least 55% compared to the best numerical approximation from the literature. An error reduction in the power coefficient parameter may have a large impact on many wind energy conversion system studies, such as those treating dynamic and transient behaviours.
Wave amplitude modulation in fan loops as observed by AIA/SDO
Authors: Sharma Aishawnnya , Tripathi Durgesh , Erdélyi Robertus , Gupta Girjesh R. , Ahmed Gazi A.
Published: April 2020

Aims. We perform a detailed analysis to understand the evolution and dynamics of propagating intensity disturbances observed in a fan loop system.

Methods. We performed multiwavelength time-distance analysis of a fan loop system anchored in an isolated sunspot region (AR 12553). The active region was observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We measured the phase speeds of the propagating intensity disturbances by employing cross-correlation analysis, and by obtaining the slopes in xt-plots. We obtained original and detrended light curves at different heights of the time-distance maps and characterised them by performing Fourier and wavelet analysis, respectively.

Results. The time-distance maps reveal clear propagation of intensity oscillations in all the coronal extreme ultraviolet (EUV) channels except AIA 94 and 335 Å. We determine the nature of the intensity disturbances as slow magneto-acoustic waves by measuring their phase speeds. The time-distance maps, as well as the detrended light curves, show an increase and decrease in the amplitude of propagating 3 min oscillations over time. The amplitude variations appear most prominently in AIA 171 Å, though other EUV channels also show such signatures. The Fourier power spectrum yields the presence of significant powers with several nearby frequencies in the range of 2–3 min (5–8 mHz), along with many other smaller peaks between 2–4 min. Wavelet analysis shows an increase and decrease of oscillating power around 3 min simultaneous to the amplitude variations. We obtain the modulation period to be in the range of 20–30 min.

Conclusions. Our results provide the viability of occurrence of phenomenon like “Beat” among the nearby frequencies giving rise to the observed amplitude modulation. However, we cannot at this stage rule out the possibility that the modulation may be driven by variability in an underlying unknown source.
Gallium and indium nanomaterials for environmental protection
Authors: Panayotova Marinela , Panayotov Vladko , Oliinyk Tetiana
Published: April 2020

Recent advances in preparation and use of gallium and indium nanoparticles and nanocomposites are briefly presented. The following applications of the obtained materials are outlined: (i) Preparation of sensors for measuring in air of gaseous pollutants (carbon monoxide, nitrogen dioxide, hydrogen sulfide, ammonia, ozone, hydrogen), vapours of volatile organic compounds (methanol, ethanol, butanol, acetone, liquefied petroleum gas), and humidity, including the basics of the sensing mechanism; (ii) removal of water pollutants by photocatalysis and/or adsorption. Finally, conclusions are drawn about the potential of gallium and indium nanoparticles and nanocomposites and the further studies needed to achieve the implementation of these materials in the real life.
The hypothesis about the influence of electrical phenomena on geological processes and global disasters
Authors: Plugin Arkadiy , Plugin Andrii , Pluhin Oleksii , Plugin Dmytro , Borziak Olga
Published: April 2020

Global Warming is officially recognized as one of the aspects to the Earth’s climate change; and its major factor is a sharp anthropogenic increase in concentration of greenhouse gases, especially carbon dioxide (CO2). However many scientists do not agree with this view and do not consider the anthropogenic factor as its basic reason, thus regarding measures for limiting greenhouse gas emissions as useless. The authors believe that a real reason is lack of unequivocal ideas in the framework of the Earth Science. The objective of the research presented in the article is to establish true reasons for global catastrophes, global warming, their rapid increase of recent decades, and their hazard level, as well as to reveal their nature and actual mechanisms. The authors critically analyzed and compared the existing data on global processes and catastrophes on Earth from ancient times to nowadays, revealed their actual mechanisms on the basis of Submicroand Macrocolloid Chemistry and Physical-Chemical Mechanics of Earth, a new science on Earth set up by the authors. The authors demonstrated that the motive power of all global phenomena and processes on Earth is the electric force, conditioned by the surplus negative electric charge of Earth, and the reason of the approaching global catastrophe is an abnormal increase of the charge in recent decades. The article deals with critical analysis of experimental data on dynamics of global catastrophes, among them the change in Earth’s temperature and level of ocean, a greater amount of carbon gas and atmosphere dust.
Method for optimizing the protecting pillars parameters in underground coal mining
Authors: Bondarenko Volodymyr , Kovalevska Iryna , Symanovych Hennadii , Poimanov Serhii , Pochepov Viktor
Published: April 2020

A method for optimizing the protecting pillars parameters during the study of soft enclosing rocks (in Ukraine mines) is represented. The necessity of a differentiated approach has been substantiated when choosing the protecting pillar parameters based on the geomechanical factors analysis influencing the state of massif. Mining and geological situation was analysed. It has been studied a stress-strain state (SSS) along the protecting pillar width with account of the mined-out space on the basis of a computational experiment and is presented in the form of curves of vertical and horizontal stresses distribution, as well as stresses intensity distribution. The recommended engineering decisions have been substantiated and the SSS of fastening and security structures has been analysed. A certain reserve of the fastening structure loadbearing capacity as part of the frame support and the combined roof-bolting system has been revealed. An evidence base has been created for the measures development on conducting and maintaining mine workings in the zone of the stope works influence. The recommendations have been developed on the protecting pillar formation with a width of at least 40 – 45 m to exclude the stope works influence.
The tragic consequences of the collapse of the earth’s surface within the mining allotment of Ordzhonikidze mine
Authors: Lapshyn Oleksandr Ye. , Lapshyn Oleksandr O. , Khudyk Mykola
Published: April 2020

The purpose of this study is to draw the attention of scientists and mining workers to the importance of working off mineral deposits within the permissible parameters of mining and technical production, the failure of which leads to tragic consequences. Based on the analysis of physical data of the rock massif and the geomechanical condition of the exhausted space within the mine field, the causes of disturbances of the stability of the inter-dimensional pillar, its deformation and displacement were determined. The negative and dangerous factors of underground mining are given, which lead to the formation of large cavities, which are kept from collapses due to the inter-dimensional pillar and the thickness of the rocks that supported it. An analysis of the field development violations is given regarding the application of inappropriate systems of development, legislation, regulations, and inefficient design decisions that led to the accident that resulted from these violations. The actual consequences of the accident, which resulted in extensive destruction of the earth’s surface, human casualties, seizure of cars, communications, buildings, roads, etc., are presented. Recommendations are given to prevent the collapse of the earth’s surface, the destruction of buildings, and the death of people.
The study of the stress-strain state of the massif in mining uranium at “VOSTGOK” deposits
Authors: Stupnik Mykola , Kalinichenko Vsevolod , Fedko Mykhailo , Kalinichenko Olena , Hryshchenko Mykhailo
Published: April 2020

Being one of the world’s largest uranium producers(about 2% of the world’s production), the state enterprise “Vostochnyi Mining and Processing Works” (“VostGOK”) provides about 40% of Ukraine’s nuclear power stations with uranium raw materials. Considering the conditions of uranium deposits exploitation (location in densely populated areas, protected sites etc.), to protect the environment from possible emissions of radioactive elements room mining is applied with subsequent backfilling of the dead area with consolidating mixtures. This technology is economically reasonable at deposits with the increased uranium content. To exclude a number of labour-consuming and environmentally dangerous operations from the production process, lean uranium-containing ores are reasonable to be mined applying underground block leaching. This enables reaching maximum values of mineral extraction and avoiding considerable material expenditures on backfilling mixture preparation and backfilling dead rooms, as they are almost completely backfilled with the muck pile, and on utilization of waste after the mined ore primary processing (barren rocks and off-balance ores) on the daylight surface.
Analysis of consumption and ensuring energy resources of the Dnipropetrovsk Region
Authors: Syvyi Myroslav , Panteleeva Natalia , Burman Liudmyla , Kalinichenko Olga , Provozhenko Mykhailo
Published: April 2020

The issue of energy-saving and energy efficiency is actual at the present-day development of Ukraine’s economy. The imperfective system of energy ensuring as the result of inefficient energy resources utilization is a characteristic feature of the state. The analysis of ensuring energy resources applied to Dnipropetrovsk Region as one of the leading industrial regions of the country is presented in the article. The availability of reserves and production of fuel resources was analyzed in it. Distinctive features of energy resources consumption with the aim of assessment general and partial indexes of energy ensuring and fuel power-intensity of the region’s economic complex are highlighted in the work. The tendencies and perspectives of energy consumption development of the Dnipropetrovsk Region were analyzed herewith.
Photovoltaic and wind energy: challenges and solutions in desert regions
Authors: Al-Dousari Ali , Al-Nassar Waleed , Ahmed Modi
Published: April 2020

In desert areas, some challenges have the prospective to reduce photovoltaic energy production. These are the creation of finely crusted carbonates and/or mud coatings resulted from fallen aerosols and dust during humid conditions. These challenges that greatly affect solar panel planes, as well as wind turbines, were allocated to accomplish the practicability to establish wind and/or photovoltaic energy systems in Kuwait. It was concluded that solar cells are not the best appropriate energy source in Kuwait due to the above-listed challenges; therefore, substitute renewable energy types are considered more practicable. After one year of operation at photovoltaic units and wind turbines in Kuwait, the outcomes show that wind turbines record production energy numbers that go beyond the production average. This was connected with high capacity factors during one year, consequential in an annual power production that is 2.3 times greater than that of solar panels; running 450 homes compared to 199 homes for photovoltaic (PV). Bubiyan Island and west of Kuwait are the most suitable potential location for wind farm establishment. Several control measures including the establishment of green belts and plantation of native shrubs were found proper in reducing dust by 64.5% and 68.4, respectively.