bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity Analysis and Calibration of an Integrated Hydrologic Model in an Irrigated Agricultural Basin With a Groundwater‐Dependent Ecosystem
Authors: Tolley D. , Foglia L. , Harter T.
Published: June 2019

While sensitivity analysis and calibration are common practice in integrated hydrologic modeling, little work has been done to understand how the design of the sensitivity analysis and calibration affects the simulation outcome in these often highly nonlinear models. This is especially true for irrigated agricultural basins with a strong connection between land use, groundwater, and surface water. Using a range rather than a single set of initial parameter values, multiple sensitivity analyses, calibrations, and linearity tests were performed using UCODE_2014 on the Scott Valley Integrated Hydrologic Model. Calibration results show that parameters related to crop demand and applied irrigation water are most sensitive. Influence statistics show that low streamflow observations provide the most information during model calibration, indicating preference should be given to these observations during model development, sensitivity analysis, and calibration. Importantly, due to the nonlinearity of the integrated model, significant differences are found in results when initial parameter values are sampled from within their respective expected ranges. Estimates for some parameters varied up to an order of magnitude between calibrations, while all produced similar final objective function values, groundwater elevations, and stream flow. Confidence intervals for individual sensitivity analyses and calibration runs only spanned a fraction of the ensemble estimated parameter range across multiple runs. Our work suggests that a calibration design with multiple sensitivity analyses and calibrations of integrated hydrologic models, each using one of several widely varying sets of initial values, provides a frugal approach to identify parameters across the global parameter space.
Changes in Fire Activity in Africa from 2002 to 2016 and Their Potential Drivers
Authors: Zubkova Maria , Boschetti Luigi , Abatzoglou John T. , Giglio Louis
Published: June 2019

While several studies have reported a recent decline in area burned in Africa, the causes of this decline are still not well understood. In this study, we found that from 2002 to 2016 burned area in Africa declined by 18.5%, with the strongest decline (80% of the area) in the Northern Hemisphere. One third of the reduction in burned area occurred in croplands, suggesting that changes in agricultural practices (including cropland expansion) are not the predominant factor behind recent changes in fire extent. Linear models that considered interannual variability in climate factors directly related to biomass productivity and aridity explained about 70% of the decline in burned area in natural land cover. Our results provide evidence that despite the fact that most fires are human‐caused in Africa, increased terrestrial moisture during 2002–2016 facilitated declines in fire activity in Africa.
Cyanobacteria and cyanophage contributions to carbon and nitrogen cycling in an oligotrophic oxygen-deficient zone
Authors: Fuchsman Clara A , Palevsky Hilary I , Widner Brittany , Duffy Megan , Carlson Michael C G , Neibauer Jacquelyn A , Mulholland Margaret R , Keil Richard G , Devol Allan H , Rocap Gabrielle
Published: June 2019

Up to half of marine N losses occur in oxygen-deficient zones (ODZs). Organic matter flux from productive surface waters is considered a primary control on N2 production. Here we investigate the offshore Eastern Tropical North Pacific (ETNP) where a secondary chlorophyll a maximum resides within the ODZ. Rates of primary production and carbon export from the mixed layer and productivity in the primary chlorophyll a maximum were consistent with oligotrophic waters. However, sediment trap carbon and nitrogen fluxes increased between 105 and 150 m, indicating organic matter production within the ODZ. Metagenomic and metaproteomic characterization indicated that the secondary chlorophyll a maximum was attributable to the cyanobacterium Prochlorococcus, and numerous photosynthesis and carbon fixation proteins were detected. The presence of chemoautotrophic ammonia-oxidizing archaea and the nitrite oxidizer Nitrospina and detection of nitrate oxidoreductase was consistent with cyanobacterial oxygen production within the ODZ. Cyanobacteria and cyanophage were also present on large (>30 μm) particles and in sediment trap material. Particle cyanophage-to-host ratio exceeded 50, suggesting that viruses help convert cyanobacteria into sinking organic matter. Nitrate reduction and anammox proteins were detected, congruent with previously reported N2 production. We suggest that autochthonous organic matter production within the ODZ contributes to N2 production in the offshore ETNP.
Retinal structure in Leber’s congenital amaurosis caused by RPGRIP1 mutations
Authors: Miyamichi Daisuke , Nishina Sachiko , Hosono Katsuhiro , Yokoi Tadashi , Kurata Kentaro , Sato Miho , Hotta Yoshihiro , Azuma Noriyuki
Published: June 2019

This study aimed to evaluate retinal structure in the early stage of Leber’s congenital amaurosis (LCA) caused byRPGRIP1mutations. Four patients from two families were included. Case 1 was a 13-year-old girl, cases 2 and 3 were 7-year-old monozygotic twin brothers of case 1, and case 4 was a 17-year-old boy. Comprehensive ophthalmic examinations were performed, including visual acuity measurements, perimetry, electroretinography (ERG), and optical coherence tomography (OCT). To identify potential pathogenic mutations, 74 genes known to cause retinitis pigmentosa or LCA were assessed using targeted next-generation sequencing. OCT showed photoreceptor outer nuclear layer (ONL) thinning in all patients. The lamellar structure was retained in all patients, whereas the ellipsoid zone was extinguished in cases 1, 2, and 3. In case 4, the ellipsoid zone was maintained at 9 years of age but became blurred at 17 years of age. In case 1, OCT indicated slight photoreceptor ONL thinning during the period between 7 and 11 years of age. Mutation analysis revealedRPGRIP1mutations as the cause for autosomal recessive LCA in all patients. Photoreceptor ONL on OCT is relatively well preserved in the early stage of LCA caused byRPGRIP1mutations.
Complex electronic structure and compositing effect in high performance thermoelectric BiCuSeO
Authors: Ren Guang-Kun , Wang Shanyu , Zhou Zhifang , Li Xin , Yang Jiong , Zhang Wenqing , Lin Yuan-Hua , Yang Jihui , Nan Ce-Wen
Published: June 2019

BiCuSeO oxyselenides are promising thermoelectric materials, yet further thermoelectric figure of merit ZT improvement is largely limited by the inferior electrical transport properties. The established literature on these materials shows only one power factor maximum upon carrier concentration optimization, which is typical for most thermoelectric semiconductors. Surprisingly, we found three power factor maxima when doping Bi with Pb. Based on our first-principles calculations, numerical modeling, and experimental investigation, we attribute the three maxima to the Fermi energy optimization, band convergence, and compositing effect due to in situ formed PbSe precipitates. Consequently, three ZT peaks of 0.9, 1.1, and 1.3 at 873 K are achieved for 4, 10, and 14 at.% Pb-doped samples, respectively, revealing the significance of complex electronic structure and multiple roles of Pb in BiCuSeO. The results establish an accurate band structure characterization for BiCuSeO and identify the role of band convergence and nanoprecipitation as the driving mechanism for high ZT.
Oxidative post-translational modification of EXECUTER1 is required for singlet oxygen sensing in plastids
Authors: Dogra Vivek , Li Mingyue , Singh Somesh , Li Mengping , Kim Chanhong
Published: June 2019

Environmental information perceived by chloroplasts can be translated into retrograde signals that alter the expression of nuclear genes. Singlet oxygen (1O2) generated by photosystem II (PSII) can cause photo-oxidative damage of PSII but has also been implicated in retrograde signaling. We previously reported that a nuclear-encoded chloroplast FtsH2 metalloprotease coordinates 1O2-triggered retrograde signaling by promoting the degradation of the EXECUTER1 (EX1) protein, a putative 1O2 sensor. Here, we show that a 1O2-mediated oxidative post-translational modification of EX1 is essential for initiating 1O2-derived signaling. Specifically, the Trp643 residue in DUF3506 domain of EX1 is prone to oxidation by 1O2. Both the substitution of Trp643 with 1O2-insensitive amino acids and the deletion of the DUF3506 domain abolish the EX1-mediated 1O2 signaling. We thus provide mechanistic insight into how EX1 senses 1O2 via Trp643 located in the DUF3506 domain.
Author Correction: Anchoring cortical granules in the cortex ensures trafficking to the plasma membrane for post-fertilization exocytosis
Authors: Vogt Edgar-John , Tokuhiro Keizo , Guo Min , Dale Ryan , Yang Guanghui , Shin Seung-Wook , Movilla Maria Jimenez , Shroff Hari , Dean Jurrien
Published: June 2019

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Dominant TOM1 mutation associated with combined immunodeficiency and autoimmune disease
Authors: Keskitalo Salla , Haapaniemi Emma M. , Glumoff Virpi , Liu Xiaonan , Lehtinen Ville , Fogarty Christopher , Rajala Hanna , Chiang Samuel C. , Mustjoki Satu , Kovanen Panu , Lohi Jouko , Bryceson Yenan T. , Seppänen Mikko , Kere Juha , Heiskanen Kaarina , Varjosalo Markku
Published: June 2019

Mutations in several proteins functioning as endolysosomal components cause monogenic autoimmune diseases, of which pathogenesis is linked to increased endoplasmic reticulum stress, inefficient autophagy, and defective recycling of immune receptors. We report here a heterozygous TOM1 p.G307D missense mutation, detected by whole-exome sequencing, in two related patients presenting with early-onset autoimmunity, antibody deficiency, and features of combined immunodeficiency. The index patient suffered from recurrent respiratory tract infections and oligoarthritis since early teens, and later developed persistent low-copy EBV-viremia, as well as an antibody deficiency. Her infant son developed hypogammaglobulinemia, autoimmune enteropathy, interstitial lung disease, profound growth failure, and treatment-resistant psoriasis vulgaris. Consistent with previous knowledge on TOM1 protein function, we detected impaired autophagy and enhanced susceptibility to apoptosis in patient-derived cells. In addition, we noted diminished STAT and ERK1/2 signaling in patient fibroblasts, as well as poor IFN-γ and IL-17 secretion in T cells. The mutant TOM1 failed to interact with TOLLIP, a protein required for IL-1 recycling, PAMP signaling and autophagosome maturation, further strengthening the link between the candidate mutation and patient pathophysiology. In sum, we report here an identification of a novel gene, TOM1, associating with early-onset autoimmunity, antibody deficiency, and features of combined immunodeficiency. Other patient cases from unrelated families are needed to firmly establish a causal relationship between the genotype and the phenotype.
Antenatal exposure to solar radiation and learning disabilities: Population cohort study of 422,512 children
Authors: Hastie Claire E. , Mackay Daniel F. , Clemens Tom L. , Cherrie Mark P. C. , King Albert , Dibben Chris , Pell Jill P.
Published: June 2019

Learning disability varies by month of conception. The underlying mechanism is unknown but vitamin D, necessary for normal brain development, is commonly deficient over winter in high latitude countries due to insufficient ultraviolet radiation. We linked the 2007–2016 Scottish School Pupil Censuses to Scottish maternity records and to sunshine hours and antenatal ultraviolet A/B radiation exposure derived from weather stations and satellites respectively. Logistic regression analyses were used to explore the associations between solar radiation, then ultraviolet B, and learning disabilities, adjusting for the potential confounding effects of month of conception and sex. Of the 422,512 eligible, singleton schoolchildren born at term in Scotland, 79,616 (18.8%) had a learning disability. Total antenatal sunshine hours (highest quintile; adjusted OR 0.89; 95% CI: 0.86, 0.93; p < 0.001) and ultraviolet B exposure (highest quintile; adjusted OR 0.55; 95% CI: 0.51, 0.60; p < 0.001) were inversely associated with learning disabilities with evidence of a dose-relationship. The latter association was independent of ultraviolet A exposure. Significant associations were demonstrated for exposure in all three trimesters. Low maternal exposure to ultraviolet B radiation may play a role in the seasonal patterning of learning disabilities. Further studies are required to corroborate findings and determine the effectiveness of supplements.
Effect of Leptin Deficiency on the Skeletal Response to Hindlimb Unloading in Adult Male Mice
Authors: Keune Jessica A. , Branscum Adam J. , Wong Carmen P. , Iwaniec Urszula T. , Turner Russell T.
Published: June 2019

Based on body weight, morbidly obese leptin-deficientob/obmice have less bone than expected, suggesting that leptin plays a role in the skeletal response to weight bearing. To evaluate this possibility, we compared the skeletal response of wild type (WT) andob/obmice to hindlimb unloading (HU). Mice were individually housed at 32 °C (thermoneutral) from 4 weeks of age (rapidly growing) to 16 weeks of age (approaching skeletal maturity). Mice were then randomized into one of 4 groups (n = 10/group): (1) WT control, (2) WT HU, (3)ob/obcontrol, and (4)ob/obHU and the results analyzed by 2-way ANOVA.ob/obmice pair-fed to WT mice had normal cancellous bone volume fraction (BV/TV) in distal femur, lower femur length and total bone area, mineral content (BMC) and density (BMD), and higher cancellous bone volume fraction in lumbar vertebra (LV). HU resulted in lower BMC and BMD in total femur, and lower BV/TV in distal femur and LV in both genotypes. Cancellous bone loss in femur in both genotypes was associated with increases in osteoclast-lined bone perimeter. In summary, leptin deficiency did not attenuate HU-induced osteopenia in male mice, suggesting that leptin is not required for bone loss induced by unweighting.
Tungsten Trioxide (WO3)-assisted Photocatalytic Degradation of Amoxicillin by Simulated Solar Irradiation
Authors: Nguyen Thao Thi , Nam Seong-Nam , Son Jooyoung , Oh Jeill
Published: June 2019

This study investigates the photocatalytic degradation of amoxicillin (AMO) by simulated solar irradiation using WO3 as a catalyst. A three-factor-three-level Box-Behnken design (BBD) consisting of 30 experimental runs is employed with three independent variables: initial AMO concentration, catalyst dosage, and pH. The experimental results are analyzed in terms of AMO degradation and mineralization, the latter of which is measured using dissolved organic carbon (DOC). The results show that the photocatalytic degradation of AMO follows pseudo-first-order kinetics. AMO degradation efficiency and the pseudo-first-order rate constants decrease with increasing initial AMO concentration and pH and increase with increasing catalyst dosage. Though AMO degradation is almost fully complete under the experimental conditions, DOC removal is much lower; the highest DOC removal rate is 35.82% after 180 min. Using these experimental results, second-order polynomial response surface models for AMO and DOC removal are constructed. In the AMO removal model, the first-order terms are the most significant contributors to the prediction, followed by the quadratic and interaction terms. Initial AMO concentration and pH have a significant negative impact on the photocatalytic degradation of AMO, while catalyst dosage has a significant positive impact. In contrast, in the DOC removal model, the quadratic terms make the most significant contribution to the prediction and the first-order terms the least. The optimal conditions for the photocatalytic degradation of AMO are found to be an initial AMO concentration of 1.0 μM, a catalyst dosage of 0.104 g/L, and a pH of 4, under which almost complete removal of AMO is achieved (99.99%).
Application of Step, Cumulative, and Global E-factor and Process Mass Intensity Metrics to Gauge Synthesis Efficiency: l-DOPA and Apixaban Pharmaceutical Examples
Authors: Andraos John
Published: June 2019

The utility of step, cumulative, and global E-factor and process mass intensity metrics is demonstrated for the analysis of the material efficiency of synthesis plans for the pharmaceuticals l-DOPA and apixaban. The mathematical relationships relating global and cumulative metrics to step metrics are applicable to any synthesis plan for any molecule.
Renewable Starting Materials, Biocatalysis, and Multicomponent Reactions: A Powerful Trio for the Green Synthesis of Highly Valued Chemicals
Authors: Banfi L. , Lambruschini C. , Moni L. , Riva R.
Published: June 2019

This chapter illustrates a series of recent examples on the cooperation of multicomponent reactions with biocatalysis and/or with the use of renewable starting materials derived from biomass. Teaming these three green methodologies affords important benefits from the point of view of sustainable synthesis. In particular, biocatalysts have been used to (i) generate enantiopure inputs for multicomponent reactions, (ii) resolve racemic multicomponent products, and (iii) catalyze the multicomponent process itself. As far as it concerns renewable inputs, this chapter will focus on the exploitation of diols, furan derivatives, levulinic acid, and lipids.
New and Up-and-coming Perspectives for Unconventional Chemistry: From Molecular Synthesis to Hybrid Materials by Mechanochemistry
Authors: Charnay Clarence , Porcheddu Andrea , Delogu Francesco , Colacino E.
Published: June 2019

In recent years, research on enabling energy sources capable of promoting chemical reactions with low environmental impact and useful to drive the development of innovative, green, and sustainable processes has been continuously growing. We report herein selected examples based on the use of mechanochemistry as a valid and reliable alternative to chemistry in solution for the preparation of pharmaceutical materials, active co-crystals, or hybrid nanoparticles.
Transition Metal Catalysis in Micellar Media: Much More Than a Simple Green Chemistry Promise
Authors: Scarso Alessandro , Strukul Giorgio
Published: June 2019

Over the past few years, micellar catalysis with transition metal complexes has become a major tool in the hands of synthetic organic chemists and an important ‘green’ technology as it allows the use of water as the reaction medium. The range of reactions in which micellar media can be successfully used is already very wide. The use of micelles can improve the yield, selectivity at all levels (chemo-, regio-, enantio-), reaction conditions, product separation, and catalyst recycling. The surfactant choice is a key issue that, for specific cases, can be optimized with especially designed surfactants and metallo-surfactants. Practical examples provide some metrics demonstrating that micellar catalysis can indeed reduce the E-factor and, in the industrial practice, also improve yields, decrease energy consumption, shorten cycle times, and ultimately production costs. In short, catalysis in micellar media is much ahead of a mere green chemistry promise and can already be considered a profitable industrial opportunity.
CO2 and Organic Carbonates for the Sustainable Valorization of Renewable Compounds
Authors: Selva Maurizio , Perosa Alvise , Fiorani Giulia , Cattelan Lisa
Published: June 2019

The present chapter collects and describes representative examples from the current literature on the use of CO2 and Organic Carbonates for the Sustainable Valorization of Renewable Compounds. For the reader's convenience, after an introductory section aimed at highlighting both the potential and challenges associated with the chemical upgrading of renewable compounds, topics are organized in three parts surveying the following subjects: (i) catalytic and photocatalytic routes for both the reduction of CO2 and use of CO2 for the carboxylation of C(sp3)–H bonds and bio-based epoxides, and the methylation of amines; (ii) model strategies for carboxylation and alkylation reactions mediated by non-toxic dialkyl carbonates for the valorization of bio-based platform chemicals including glycerol, succinate, and dimethyl-2,5-furandicarboxylate, and renewable lactones, as well as natural polysaccharides (cellulose, starch, and chitin) and lignin; (iii) the sustainable synthesis of bio-polycarbonates and bio-polyurethanes via sequential transesterification/polycondensation reactions with dialkyl carbonates and cycloadditions of CO2 into renewable epoxides.
Long magnetic relaxation time of tetracoordinate Co2+ in imidazo[1,5-a]pyridinium-based (C13H12N3)2[CoCl4] hybrid salt and [Co(C13H12N3)Cl3] molecular complex
Authors: Vassilyeva Olga Yu. , Buvaylo Elena A. , Kokozay Vladimir N. , Skelton Brian W. , Rajnák Cyril , Titiš Ján , Boča Roman
Published: June 2019

Co(ii) SIMs with simple tetrahedral environments and low positive magnetic anisotropy are unique with respect to the remarkably long relaxation time for a given applied DC field and temperature.
Carbon–carbon bond forming reactions of acetylenic esters and ketones within frustrated phosphane/borane Lewis pair frameworks
Authors: Wang Long , Li Jun , Deng Dongsheng , Daniliuc Constantin G. , Mück-Lichtenfeld Christian , Kehr Gerald , Erker Gerhard
Published: June 2019

The three-component reactions of bulky diarylbutenylphosphanes with dimethyl acetylenedicarboxylate and the strong boron Lewis acid B(C6F5)3 give the ylide-substituted cyclopropane derivatives.
Polarity control in a single transition metal dichalcogenide (TMD) transistor for homogeneous complementary logic circuits
Authors: Shim Jaewoo , Jang Sung woon , Lim Ji-Hye , Kim Hyeongjun , Kang Dong-Ho , Kim Kwan-Ho , Seo Seunghwan , Heo Keun , Shin Changhwan , Yu Hyun-Yong , Lee Sungjoo , Ko Dae-Hong , Park Jin-Hong
Published: June 2019

We report a polarity controllable TMD transistor that can operate as both an n- and a p-channel transistor. We then demonstrate a complementary inverter circuit on a single TMD material and its expandability toward a three-stage ring oscillator.
Topological phase transition induced by px,y and pz band inversion in a honeycomb lattice
Authors: Zhang Huisheng , Ning Yaohui , Yang Wenjia , Zhang Ruiqiang , Xu Xiaohong
Published: June 2019

The search for more types of band inversion-induced topological states is of great scientific and experimental interest. Here, we proposed that the band inversion between px,y and pz orbitals can produce a topological phase transition in honeycomb lattices.
Cyanogel auto-reduction induced synthesis of PdCo nanocubes on carbon nanobowls: a highly active electrocatalyst for ethanol electrooxidation
Authors: Xu Guang-Rui , Zhai Ya-Nan , Li Fu-min , Zhao Guang-Tao , Li Shu-Ni , Yao Hong-Chang , Jiang Jia-Xing , Chen Yu
Published: June 2019

Direct ethanol fuel cells (DEFCs) with a high conversion efficiency are quite promising candidates for energy conversion devices.
One-pot synthesis of pyranoquinolin-1-ones via Rh(iii)-catalysed redox annulation of 3-carboxyquinolines and alkynes
Authors: Yang Zhijia , Pi Chao , Cui Xiuling , Wu Yangjie
Published: June 2019

A highly efficient and simple one-pot procedure to synthesize 3,4-dihydro-pyrano[4,3-b]quinolin-1-ones via Rh(iii)-catalysed [4 + 2] redox annulation of 3-carboxyquinolines with internal alkynes.
Tumour suppression by targeted intravenous non-viral CRISPRa using dendritic polymers
Authors: Kretzmann Jessica A. , Evans Cameron W. , Moses Colette , Sorolla Anabel , Kretzmann Amy L. , Wang Edina , Ho Diwei , Hackett Mark J. , Dessauvagie Benjamin F. , Smith Nicole M. , Redfern Andrew D. , Waryah Charlene , Norret Marck , Iyer K. Swaminathan , Blancafort Pilar
Published: June 2019

This article demonstrates a fully synthetic strategy enabling CRISPR-mediated activation of tumour suppressor genes in vivo to reduce tumour burden.
Organobase triggered controlled supramolecular ring opening polymerization and 2D assembly
Authors: Chakraborty Anwesha , Ghosh Goutam , Pal Deep Sankar , Varghese Shinto , Ghosh Suhrit
Published: June 2019

Spontaneously aggregation of a carboxylic acid appended NDI can be retarted by intra-molecular H-bonding. With catalytic DMAP or DBU, the meta-stable monomer exhibits living supramolecular polymerization and generates ultra-thin 2D sheet.
Enhancing the production of hydrogen peroxide from electrocatalytic oxygen reduction reaction by tailoring the electronic states of single-walled carbon nanotubes: a synergistic effect from interior filling and exterior oxidation
Authors: Hu Rongtao , Yao Fenfa , Wu Chuxin , Jin Chuanhong , Guan Lunhui
Published: June 2019

Single-walled carbon nanotubes co-modified with interior filling of phosphomolybdic acid and successive exterior oxidation (O-HPMO@SWCNTs) possess better two-electron oxygen reduction reaction performance than the HPMO-filled SWCNTs, oxidized SWCNTs or pristine SWCNTs.
CNN‐based CSI acquisition for FDD massive MIMO with noisy feedback
Authors: Sun Qiang , Wu Yezeng , Wang Jue , Xu Chen , Wong Kai‐Kit
Published: June 2019

In frequency‐division‐duplex (FDD) massive multiple‐input multiple‐output (MIMO) systems, noisy feedback is a constant challenge for the base station (BS) to acquire accurate downlink channel state information (CSI). In this Letter, the authors propose a convolutional neural network (CNN)‐based approach to overcome this problem, which they refer to it as an anti‐noise CSI acquisition network (ANCAN). Results demonstrate that ANCAN can reconstruct CSI more accurately than other emerging CSI acquisition methods in the presence of noisy feedback links.
Fairness‐based multi‐task reward allocation in mobile crowdsourcing system
Authors: Hou Jian , Luo Shuyun , Xu Weiqiang , Wang Lili
Published: June 2019

Mobile crowdsourcing‐based applications, widely popular, exploit the sensing data crowdsourced from smartphone users without putting any burden on the extra cost of data sensing and collection. However, user participation in crowdsourcing incurs resource cost, such as battery, bandwidth, thus it is critical to design incentive mechanisms for propelling user's participation. Previous diverse incentive mechanisms designed for crowdsourcing applications only focus on users' contribution for reward allocation, while ignore another important property, i.e. fairness, users' reward should be corresponding with their cost. In this study, the authors first introduce a new concept called rate of return (RoR), defined as the ratio of received reward and incurred cost for each user, to demonstrate the property of fairness. With the goal of guarantee, the fairness of reward allocation for each user in a multiple‐task system, three algorithms, consensus‐based reward allocation, consensus‐based balanced topology reward allocation and Gossip‐based reward allocation are proposed for the demands of various scenarios, in which the RoR values are synchronised by optimising the fairness function in either centralised or decentralised manner. Through rigorous theoretical analysis and extensive simulations, it is finally demonstrated that the proposed reward allocation algorithms have the good property of fairness with quick convergence.
Deep reinforcement learning‐based beam Hopping algorithm in multibeam satellite systems
Authors: Hu Xin , Liu Shuaijun , Wang Yipeng , Xu Lexi , Zhang Yuchen , Wang Cheng , Wang Weidong
Published: June 2019

Beam hopping (BH) is the key technology to improve the system throughput and decrease the transmission delay in multibeam satellite systems. The objective of this study is to find a policy to maximise the expected long‐term resource utilisation. The BH illumination plan (BHIP) optimisation problem aimed at minimising the transmission delay is formulated and modelled as a partially observable Markov decision process. To tackle the issue of unknown dynamics and prohibitive computation, an artificial intelligence method named deep reinforcement learning (DRL) is first proposed to solve the BHIP problem in multibeam satellite systems. The proposed DRL‐BHIP algorithm considers a series of realistic conditions, including the traffic demands in spatial distribution and temporal variation, ModCod constraints, antenna radiation pattern and inter‐beam interference. The state reformulation concept is adopted to characterise the traffic spatial and temporal features. Simulation results show that the proposed DRL‐BHIP algorithm can decrease the transmission delay and improve the system throughput compared with existing algorithms.
Statistical characterisation and analysis of differential correlation‐based frame detector
Authors: Akhlaq Assad , Ansari Imran Shafique , Lechner Gottfried , Rice Mark , Ahmad Ishtiaq
Published: June 2019

Next generation satellite systems are required to perform robust frame synchronisation in the presence of large frequency offsets at low carrier‐to‐noise ratios. Differential correlation‐based frame acquisition is an appealing choice for these systems as it provides adequate performance with reasonable complexity. However, the theoretical characterisation of the multi‐span differential correlation metric is still an open problem due to the fact that the correlation outputs with multiple delays are correlated. In this study, the authors derived novel closed‐form approximations for the distribution of the multi‐span differential correlation metric as well as the probabilities of miss‐detection and false alarm. The close agreement between the simulated and theoretical receiver operating curves validates the analysis. This analysis can be used to characterise the performance of multi‐span differential correlation‐based frame synchroniser in terms of the number of delays without running computationally extensive Monte Carlo simulations.
Computation offloading and resource allocation for mobile edge computing with multiple access points
Authors: Li Qiuping , Zhao Junhui , Gong Yi
Published: June 2019

Mobile edge computing (MEC) is an innovative computing paradigm to enhance the computing capacity of mobile devices (MDs) by offloading computation‐intensive tasks to MEC servers. With the widespread deployment of wireless local area networks, each MD can offload computation task to server via multiple wireless access points (WAPs). However, computation offloading can bring a higher system cost if all users select the same access points to offload their tasks. This study proposes a computation offloading strategy and resource allocation optimisation scheme in a multiple wireless access points network with MEC, which aims to minimise the system cost by providing the optimal computation offloading strategy, transmission power allocation, bandwidth assignment, and computation resource scheduling. The proposed scheme decouples the optimisation problem into subproblems of offloading strategy and resource allocation since the problem is NP‐hard. The offloading strategy involves the optimal access point selection, which is analysed by the potential game. The resource allocation is obtained using Lagrange multiplier. The authors' analysis and simulation results verify the convergence performance of the proposed scheme, and the proposed scheme outperforms the simple resource allocation scheme and the offloading strategy optimisation scheme in terms of the system cost.
Stability analysis of fractional order time‐delay systems: constructing new Lyapunov functions from those of integer order counterparts
Authors: Badri Vahid , Tavazoei Mohammad Saleh
Published: June 2019

This study deals with proposing a Lyapunov‐based technique for stability analysis of fractional order time‐delay systems. The proposed technique is constructed on the basis of modifying the convex part of a class of Lyapunov–Krasovskii functionals commonly used in stability analysis of integer order time‐delay systems. As a consequence for this achievement, it is revealed that the Lyapunov–Krasovskii‐based stability conditions in integer order time‐delay systems can result in stability of their fractional order counterparts defined based on Caputo/Riemann–Liouville derivative operators with orders in the range (0,1). The applicability of the study results is shown through three different case studies.
Gossip‐based distributed hierarchical algorithm for multi‐cluster constrained optimisation
Authors: Li Da‐Kuo , Shi Chong‐Xiao , Yang Guang‐Hong
Published: June 2019

This study develops a gossip‐based distributed hierarchical algorithm to solve the constrained convex optimisation problem over a multi‐cluster network. Different from the existing works with incremental communication approach, a gossip protocol is applied to achieve inter‐cluster information exchange. At each iteration, only two neighbour clusters are randomly woken up to exchange their new updates while others keep their latest information, which relaxes the restrictions on the inter‐cluster communication topology. Technically, to investigate the intra‐cluster consensus, a new analysing approach is exploited and some different techniques including the non‐expansiveness of projection operator and the supermartingale convergence results are employed, based on which it is proved that estimates of all agents in the multi‐cluster network jointly converge to the optimal solution with probability one. A numerical example on constrained lasso regression is provided to validate the theoretical results.
Impacts of intraday risky power trades on the high wind penetrated electricity markets
Authors: Bashi Mazaher Haji , Yousefi Gholam Reza , Latify Mohammad Amin , Bak Claus Leth
Published: June 2019

In this study, a three‐settlement electricity market including the day‐ahead, risky, and real‐time trades is analysed. A wind power producer faces generation uncertainty and needs to cover its real‐time generation deviation unless it would be penalised. To do so, wind power producers participate in an intraday risky power market, as well as in the day‐ahead and real‐time markets. Mathematical program with equilibrium constraints (MPEC) is used to model the behaviour of each generation company in its profit maximisation process. The complementarity constraints describe the market clearings and constitute a bi‐level optimisation problem for each company. The companies have a combination of wind and thermal power plants in their generation portfolios. Wind power uncertainty is modelled using plausible scenarios. The joint solution of all companies’ MPECs makes an equilibrium problem with equilibrium constraints (EPEC). This EPEC is linearised and solved using mixed integer linear programming techniques. EPEC solution gives the Nash equilibrium. Results show the effectiveness of the risky power trades on reducing the reserve requirements, increasing the wind power producers’ profit, and reducing the wind power spillage.
Research on system dynamic performances of two‐/three‐level VSC–MVDC distribution systems with different capacitor arrangement schemes
Authors: Li Bin , Ye Shilei , Wen Weijie , Wang Changqi , Liu Haijin , Zhang Weixin , Li Ruisheng
Published: June 2019

With fewer power electronic devices, the two‐/three‐level voltage source converter (VSC) is more suitable for medium‐voltage direct current (MVDC) distribution system than the modular multi‐level converter (MMC). However, two important system dynamic performances, including voltage fluctuation during a normal power change and voltage collapse during a fault, are contradictory in two existing capacitor arrangement schemes. To balance both dynamic performances, a novel capacitor arrangement scheme is proposed, with the capacitors dispersed at the source side. First, the structure and basic working principle of the proposed scheme are presented. Then, dynamic performances of two‐/three‐level VSC–MVDC system with the proposed scheme are discussed, and detailed comparisons among two existing capacitor arrangement schemes and the proposed scheme are made. In the end, simulation models of 20 kV two‐/three‐level VSC–MVDC system with the three different capacitor arrangement schemes are established in the MATLAB/Simulink platform. Simulation results have proved that in the proposed scheme, voltage fluctuation during normal power change is minimum, and voltage collapse during a short‐circuit fault is suppressed dramatically.
Robust three‐vector‐based low‐complexity model predictive current control with supertwisting‐algorithm‐based second‐order sliding‐mode observer for permanent magnet synchronous motor
Authors: Xu Yanping , Ding Xianhua , Wang Jibing , Wang Chen
Published: June 2019

This study presents a robust three‐vector‐based low‐complexity model predictive current control with supertwisting‐algorithm‐based second‐order sliding‐mode observer for permanent magnet synchronous motor (PMSM). First, to reduce the computational complexity of the three‐vector‐based model predictive current control, the optimal voltage vector combination is directly determined by the sector of desired voltage vector. Second, a supertwisting‐algorithm‐based second‐order sliding‐mode observer is designed to observe the lump disturbance caused by model mismatch and unmodelled dynamics. The estimated lump disturbance is considered as the compensation to the original PMSM model to reduce steady‐state current error, which improves the robustness of the three‐vector‐based model predictive current control. Finally, the effectiveness of the proposed method is verified by experiments on a two‐level‐inverter‐fed PMSM drive platform. Experimental results prove that, compared with three‐vector‐based model predictive current control, the proposed method can reduce the computational complexity and enhance robustness against motor parameters variation.
Analysis and experimental validation of partial shading mitigation in photovoltaic system using integrated dc–dc converter with maximum power point tracker
Authors: Ramli Mohd Zulkifli , Salam Zainal
Published: June 2019

An integrated dc–dc converter with maximum power point tracker (IDCCM) is an electronic device that can be utilised to increase the output power of a photovoltaic generation system. Despite its potential benefits, there is an absence of a comprehensive analytical work to characterise the IDCCM performance under different partial shading conditions. Thus, this work proposes an analytical method to evaluate the system with IDCCM for different shading pattern/intensity, irradiance, and temperature. To validate the analysis, the SPV 1020 boost‐type IDCCM devices are incorporated into a 2 kWp experimental test‐rig. The performance of the IDCCM is benchmarked against the conventional system that utilises bypass diodes (alone). The results indicate that the IDCCM improves the performance of the central inverter as it ensures the latter consistently tracks the global peak. Also, it was found that that the performance of the IDCCM depends on the shading intensity: at low intensity, the IDCCM is able to extract energy from the shaded modules; however, it is ineffective at high shading intensity. Furthermore, when the shading is absent, the energy gained by the IDCCM is offset by the continuous power losses due to its internal operations.
Non‐analytical direction‐finding method as a key step in pursuing low size, weight, costs, and computational power in the deinterleaving of radar pulses
Authors: Licursi de Mello Rafael Gonçalves , Rangel de Sousa Fernando
Published: June 2019

The study presents a direction‐finding method that is not limited to the main lobe zones of antenna patterns. The technique allows for the angular sector of interest to be divided by few channels, pursuing low size, weight, costs, and computational power in radar detection. Experiments done on a building rooftop have shown that, with a minimum of 150 processed pulses, the distributions of estimates of direction of arrival are well behaved, with a relationship between standard deviation and signal‐to‐noise ratio. As a result, information is provided that may soften the deinterleaving of radar pulses.
Smart energy coordination of autonomous residential home
Authors: Mbungu Nsilulu T. , Bansal Ramesh C. , Naidoo Raj M.
Published: June 2019

The smart grid technology permits the revolution of the electrical system from a conventional power grid to an intelligent power network which has led the improvements in electrical system in terms of energy efficiency and sustainable energy integration. This study presents the energy management/coordination scheme for domestic demand using the key strategy of smart grid energy efficiency modelling. The structure consists of combining renewable energy resources, photovoltaic (PV) and wind power generation connected to the utility grid with energy storage system (ESS) in an optimal control manner to coordinate the power flow of a residential home. Based on the demand response schemes in the framework of real‐time electricity pricing, this work designs a closed‐loop optimal control strategy that is created by the dynamic model of the ESS to compute the system performance index, which is formulated by the cost of the energy flows. A dynamic distributed energy storage strategy (DDESS) is implemented to optimally coordinate the energy system, which reduces the total energy consumption from the main grid of more than 100% of the load demand. The designed model introduces a payback scheme while robustly optimising the energy flows and minimising the utility grid's energy consumption cost.
Chaotic emperor penguin optimised extreme learning machine for microarray cancer classification
Authors: Baliarsingh Santos Kumar , Vipsita Swati
Published: June 2019

Microarray technology plays a significant role in cancer classification, where a large number of genes and samples are simultaneously analysed. For the efficient analysis of the microarray data, there is a great demand for the development of intelligent techniques. In this article, the authors propose a novel hybrid technique employing Fisher criterion, ReliefF, and extreme learning machine (ELM) based on the principle of chaotic emperor penguin optimisation algorithm (CEPO). EPO is a recently developed metaheuristic method. In the proposed method, initially, Fisher score and ReliefF are independently used as filters for relevant gene selection. Further, a novel population‐based metaheuristic, namely, CEPO was proposed to pre‐train the ELM by selecting the optimal input weights and hidden biases. The authors have successfully conducted experiments on seven well‐known data sets. To evaluate the effectiveness, the proposed method is compared with original EPO, genetic algorithm, and particle swarm optimisation‐based ELM along with other state‐of‐the‐art techniques. The experimental results show that the proposed framework achieves better accuracy as compared to the state‐of‐the‐art schemes. The efficacy of the proposed method is demonstrated in terms of accuracy, sensitivity, specificity, and F‐measure.
Online impedance spectroscopy estimation of a dc–dc converter connected battery using a switched capacitor‐based balancing circuit
Authors: Varnosfaderani Mina Abedi , Strickland Dani
Published: June 2019

This study investigates a novel method of undertaking online electrochemical impedance spectroscopy measurements to estimate battery impedance across the frequency range using a battery balancing circuit. A switched capacitor balancing system is used to generate an excitation signal of low‐frequency of variable values from which battery voltage and current can be measured to estimate the impedance.
Cloudlet capture by transitional disk and FU Orionis stars
Authors: Dullemond C. P. , Küffmeier M. , Goicovic F. , Fukagawa M. , Oehl V. , Kramer M.
Published: June 2019

After its formation, a young star spends some time traversing the molecular cloud complex in which it was born. It is therefore not unlikely that, well after the initial cloud collapse event which produced the star, it will encounter one or more low mass cloud fragments, which we call “cloudlets” to distinguish them from full-fledged molecular clouds. Some of this cloudlet material may accrete onto the star+disk system, while other material may fly by in a hyperbolic orbit. In contrast to the original cloud collapse event, this process will be a “cloudlet flyby” and/or “cloudlet capture” event: A Bondi–Hoyle–Lyttleton type accretion event, driven by the relative velocity between the star and the cloudlet. As we will show in this paper, if the cloudlet is small enough and has an impact parameter similar or less than GM*/v∞2 (with v∞ being the approach velocity), such a flyby and/or capture event would lead to arc-shaped or tail-shaped reflection nebulosity near the star. Those shapes of reflection nebulosity can be seen around several transitional disks and FU Orionis stars. Although the masses in the those arcs appears to be much less than the disk masses in these sources, we speculate that higher-mass cloudlet capture events may also happen occasionally. If so, they may lead to the tilting of the outer disk, because the newly infalling matter will have an angular momentum orientation entirely unrelated to that of the disk. This may be one possible explanation for the highly warped/tilted inner/outer disk geometries found in several transitional disks. We also speculate that such events, if massive enough, may lead to FU Orionis outbursts.
Fitting B/C cosmic-ray data in the AMS-02 era: a cookbook
Authors: Derome L. , Maurin D. , Salati P. , Boudaud M. , Génolini Y. , Kunzé P.
Published: June 2019

Context. AMS-02 on the International Space Station has been releasing data of unprecedented accuracy. This poses new challenges for their interpretation.

Aims. We refine the methodology to get a statistically sound determination of the cosmic-ray propagation parameters. We inspect the numerical precision of the model calculation, nuclear cross-section uncertainties, and energy correlations in data systematic errors.

Methods. We used the 1D diffusion model in USINE. Our χ2 analysis includes a covariance matrix of errors for AMS-02 systematics and nuisance parameters to account for cross-section uncertainties. Mock data were used to validate some of our choices.

Results. We show that any mis-modelling of nuclear cross-section values or the energy correlation length of the covariance matrix of errors biases the analysis. It also makes good models (χmin2/d.o.f. ≈ 1) appear as excluded (χmin2/d.o.f. ≫ 1). We provide a framework to mitigate these effects (AMS-02 data are interpreted in a companion paper).

Conclusion. New production cross-section data and the publication by the AMS-02 collaboration of a covariance matrix of errors for each data set would be an important step towards an unbiased view of cosmic-ray propagation in the Galaxy.