bluuebunny/crossref_metadata_2025 huggingface dataset:
Chlorination Strategy‐Induced Abnormal Nanomorphology Tuning in High‐Efficiency Organic Solar Cells: A Study of Phenyl‐Substituted Benzodithiophene‐Based Nonfullerene Acceptors
Authors: Yan Cenqi , Yang Tao , Gao Wei , Xiao Yiqun , Li Yuhao , Lu Xinhui , Yang Chuluo , Li Gang
Published: July 2019

A new heptacyclic core based on phenyl‐substituted benzo[1,2‐b:4,5‐b']dithiophene (BDT) is designed and paired with 1,1‐dicyano methylene‐3‐indanone (INCN) end group to construct a nonfullerene acceptor, BPIC. The strong aggregation and large phase separation in the poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))]) (PBDB‐T):BPIC blend cause inefficient exciton dissociation and ineffective charge transport, resulting in a low 11.12% power conversion efficiency (PCE) with low short‐circuit current density (JSC) and fill factor (FF). To finely control the active‐layer nanomorphology, the chlorine atom is introduced into the INCN termini, and di‐chlorinated BPIC‐2Cl and tetra‐chlorinated BPIC‐4Cl are synthesized. It is an interesting phenomenon that, unlike other literature reports, while the di‐chlorination reduces crystallinity and phase‐separation scale, further chlorination increases crystallinity and phase separation. The PBDB‐T:BPIC‐2Cl device exhibits suitable molecular packing and nearly ideal nanoscale phase separation, which facilitates exciton dissociation and charge transport and thus yields the higher PCE of 12.63% with significantly improved JSC and FF. PBDB‐T:BPIC‐4Cl device, however, exhibits strong stacking intensity and excessively large phase separation, leading to the clearly reduced JSC, FF, and PCE of only 8.23%. This work demonstrates that novel phenyl‐substituted BDT core and delicated chlorination strategy provides powerful tools for high‐performance nonfullerene acceptors in organic solar cells.
Interfacial Post‐Treatment for Enhancing the Performance of Printable Carbon‐Based Perovskite Solar Cells
Authors: Liu Tongfa , Wang Zheng , Lou Lingyun , Xiao Shuang , Zheng Shizhao , Yang Shihe
Published: July 2019

The interface between the perovskite layer and carbon electrode is important for printable carbon‐based perovskite solar cells (PSCs) to improve the power conversion efficiency (PCE) and device stability. A series of acetate salts are employed to in situ post‐modify the interface between the perovskite layer and carbon electrode for printable carbon‐based PSCs by the post‐treatment method. Cesium acetate (CsAc) is identified to enhance the average PCE from 12.6% to 15.3%. The stabilized output PCE reaches 15.6%, and the highest open‐circuit voltage (VOC) is 1.1 V, representing a new milestone in increasing the ratio of VOC/Eg (Eg: bandgap of perovskite) to be 0.67 for the printable carbon‐based PSCs without hole transporting materials. Moreover, the device stability in air is also improved by CsAc post‐modification. The improved performance is attributed to the better matching of energy levels of the perovskite layer with a carbon electrode and reduced defect density in the perovskite layer via in situ produced methylammonium acetate and ion replacement. This simple and effective CsAc post‐treatment method opens a new promising direction for developing scalable carbon‐based PSCs.
Trihydrazine Dihydriodide‐Assisted Fabrication of Efficient Formamidinium Tin Iodide Perovskite Solar Cells
Authors: Li Fengzhu , Fan Haochen , Zhang Jie , Huang Jin-Hua , Wang Pengcheng , Gao Caiyan , Yang Lian-Ming , Zhu Zonglong , Jen Alex K.-Y. , Song Yanlin , Jiang Ke-Jian
Published: July 2019

The deposition of a uniform and dense tin‐based perovskite layer with low defect‐caused background carrier density is crucial for achieving efficient tin perovskite solar cells (PSCs). These defects are mainly caused by the rapid oxidation of Sn2+ to Sn4+ in tin perovskite during device fabrication. Herein, trihydrazine dihydriodide ((N2H4)3(HI)2) is used as an additive for solution deposition of a formamidinium tin iodide (FASnI3) perovskite layer. The resultant FASnI3 layer is homogeneous with full surface coverage; moreover, the content of Sn4+ is significantly reduced in the film from the SnI2 precursor owing to the reductive property of (N2H4)3(HI)2. With the high‐quality FASnI3 layer as a light absorber, planar‐heterojunction perovskite solar cells are fabricated, exhibiting a maximum power conversion efficiency of 8.48% and good reproducibility. This work opens new possibilities for achieving efficient lead‐free tin‐based perovskite solar cells.
Precise prediction for the W boson mass in the MRSSM
Authors: Diessner Philip , Weiglein Georg
Published: July 2019

Abstract

The mass of the W boson, M

W
, plays a central role for high-precision tests of the electroweak theory. Confronting precise theoretical predictions with the accurately measured experimental value provides a high sensitivity to quantum effects of the theory entering via loop contributions. The currently most accurate prediction for the W boson mass in the Minimal R-symmetric Supersymmetric Standard Model (MRSSM) is presented. Employing the on-shell scheme, it combines all numerically relevant contributions that are known in the Standard Model (SM) in a consistent way with all MRSSM one-loop corrections. Special care is taken in the treatment of the triplet scalar vacuum expectation value v

T
that enters the prediction for M

W
already at lowest order. In the numerical analysis the decoupling properties of the supersymmetric loop contributions and the comparison with the MSSM are investigated. Potentially large numerical effects of the MRSSM-specific Λ superpotential couplings are highlighted. The comparison with existing results in the literature is discussed.
‘Small stories of closing loops’: social circularity and the everyday circular economy
Authors: Hobson Kersty
Published: July 2019

There is now no doubt that current global production-consumption-disposal systems are threatening the fundamental conditions of existence on this planet. In response, the pressing need for total system transformation has gained civic and political traction, feeding into long-standing debates and interventions that are aimed at recalibrating prevailing economic and social practices. One such debate and intervention is that of the circular economy (CE). Here, advocates argue that current linear resource and energy use systems must be reconfigured into loops of re-use, repair, refurbishment, and recycling, displacing primary production and lessening greenhouse gas emissions in the process. This agenda has potentially profound implications for aspects of daily social practices. Yet, to date, little attention has been paid (politically and in research) to how the CE does and will interact with everyday habits, norms, and meanings. In response, this paper explores some of the conceptual assumptions underlying the CE ‘consumer’. It argues that mainstream CE debates are underscored by an impoverished view of our relationships with complex material cultures, which in turn is creating barriers to transformation. Drawing on empirical research into responses to the CE in the UK and the Netherlands, this paper contrasts the challenges of inciting consumers to take up new, resource-efficient business models in contexts of hyper-consumerism, with a more hopeful ‘small story’ of overt, small-scale circular spaces, that nevertheless embed the CE and its underlying impetuses more clearly into the everyday.
Defining a mountain landscape characterized by grazing using actor perception, governmental strategy, and environmental monitoring data
Authors: Neumann Wiebke , Sandström Camilla , Holmgren Lina , Ericsson Göran
Published: July 2019

In multi-functional mountainous landscapes worldwide, conservation of natural values is a major task. Here, pro-active policies can be a way forward. National Environmental Quality Objectives (EQO) to solve environmental problems for future generations, however, often wrestle with being too visionary and lacking specificity, which complicates their implementation. The EQO “A Magnificent Mountain Landscape” that has been adopted by the Swedish Parliament in 1999 to preserve the pristine mountain environment in Sweden, experiences all these flaws. To aid its implementation, we studied the conditions and processes needed to define, to evaluate, and to preserve its goals across the Swedish mountain chain, using one of its milestone targets (a landscape characterized by grazing) as a study system. Applying qualitative and quantitative methods, we analyzed three types of data: 1) referral responses to the governmental strategy document, 2) interviews with relevant actors, and 3) environmental monitoring data (reindeer position data). Nationally, our results suggest a need for geographical differentiation to match regional/local conditions. Regionally, difference in both perception and definition of the milestone target among the actors hinders the formulation, monitoring, and evaluation of a common goal. Next to a culture-nature divide, we found that a “within as a user” and “from the outside as an observer” perspective influenced suggested definitions. Moreover, we found a need for better defining whether the goal is maintaining current conditions or restoring previous ones. Our result supports the use of animal position data as a decision support tool to monitor and to aid evaluation of the target. Given the number of actors involved and conflicts of interests present, we suggest the application of a structured decision process to accomplish agreements on a common goal. Here, environmental monitoring data can aid a “landscape assessment step” as a natural part in the decision process to target landscape management actions resourcefully and effectively.
Study of a boundary value problem for fractional order $$\psi $$-Hilfer fractional derivative
Authors: Harikrishnan S. , Shah Kamal , Kanagarajan K.
Published: July 2019

This manuscript is devoted to the existence theory of a class of random fractional differential equations (RFDEs) involving boundary condition (BCs). Here we take the corresponding derivative of arbitrary order in $$\psi $$
ψ
-Hilfer sense. By utilizing classical fixed point theory and nonlinear analysis we establish some basic results of the qualitative theory such as existence, uniqueness and stability of solutions to the considered boundary value problem of RFDEs. Further, for the justification of our analysis we provide two examples.
Profiles of individual assets and mental health symptoms in at‐risk early adolescents
Authors: Min Meeyoung O. , Yoon Dalhee , Minnes Sonia , Ridenour Ty , Singer Lynn T.
Published: July 2019

Introduction

Few studies investigated the combined patterns of individual assets (e.g., social competence, positive identity) and mental health symptoms (MHS) in adolescents. This study examined the patterns of early adolescents' individual assets and MHS and whether identified patterns were associated with later adolescents’ outcomes.

Methods

Participants were 352 (164 boys, 188 girls) adolescents who were primarily African‐American and from low socioeconomic status families, participating in a prospective study of the effects of prenatal cocaine exposure from birth in the Midwest United States. Individual assets, using the Developmental Assets Profile, and MHS, using the Youth Self‐Report, were assessed at age 12. Substance use, via self‐report and biologic assays, early (before age 15) sexual behaviors, and behavioral adjustment were assessed at age 15.

Results

Latent profile analysis indicated four distinctive profiles: low assets with elevated MHS (P1, n = 54, 15.3%); adequate assets with thought and social problems (P2, n = 84, 23.9%); low assets without MHS (P3, n = 101, 28.7%); and high assets without MHS (P4, n = 113, 32.1%). Children in the profile with high assets without MHS (P4) were more likely to have a higher IQ and to be in a more optimal environment (higher parental monitoring and less family conflict) than those in other profiles. Although profiles with MHS were associated with adolescent risk behaviors, this relationship was more pronounced for girls than for boys.

Conclusions

Girls in the low assets with elevated MHS (P1) should be a primary concern for preventive intervention. Our study demonstrates the heterogeneity of individual patterns of adaptation and maladaptation.
Utilizing the Heliophysics/Geospace System Observatory to Understand Particle Injections: Their Scale Sizes and Propagation Directions
Authors: Gabrielse Christine , Spanswick Emma , Artemyev Anton , Nishimura Yukitoshi , Runov Andrei , Lyons Larry , Angelopoulos Vassilis , Turner Drew L. , Reeves Geoffrey D. , McPherron Robert , Donovan Eric
Published: July 2019

The injection region's formation, scale size, and propagation direction have been debated throughout the years, with new questions arising with increased plasma sheet observations by missions like Cluster and THEMIS. How do temporally and spatially small‐scale injections relate to the larger injections historically observed at geosynchronous orbit? How to account for opposing propagation directions—earthward, tailward, and azimuthal—observed by different studies? To address these questions, we used a combination of multisatellite and ground‐based observations to knit together a cohesive story explaining injection formation, propagation, and differing spatial scales and timescales. We used a case study to put statistics into context. First, fast earthward flows with embedded small‐scale dipolarizing flux bundles transport both magnetic flux and energetic particles earthward, resulting in minutes‐long injection signatures. Next, a large‐scale injection propagates azimuthally and poleward/tailward, observed in situ as enhanced flux and on the ground in the riometer signal. The large‐scale dipolarization propagates in a similar direction and speed as the large‐scale electron injection. We suggest small‐scale injections result from earthward‐propagating, small‐scale dipolarizing flux bundles, which rapidly contribute to the large‐scale dipolarization. We suggest the large‐scale dipolarization is the source of the large‐scale electron injection region, such that as dipolarization expands, so does the injection. The >90‐keV ion flux increased and decreased with the plasma flow, which died at the satellites as global dipolarization engulfed them. We suggest the ion injection region at these energies in the plasma sheet is better organized by the plasma flow.
Meridional Overturning and Heat Transport From Argo Floats Displacements and the Planetary Geostrophic Method (PGM): Application to the subpolar North Atlantic
Authors: Colin de Verdière Alain , Meunier Thomas , Ollitrault Michel
Published: July 2019

A direct method is presented to obtain the meridional overturning and heat transport in oceanic basins from observations under the sole assumptions of geostrophy and hydrostatics. The method is made possible because of the rising Argo float displacements database that can provide a reference level at 1000 dbar for the time mean circulation at 1° × 1° resolution. To achieve the overturning and heat transport objectives, the absolute geostrophic time mean circulation must have nondivergent barotropic transports and this requires the solutions of two Poisson equations with suitable boundary conditions, one for the geopotential at 1000 dbar and one for the barotropic stream function. Applied to the subpolar Atlantic for the period 2000–2009, an overturning of 16–18 Sv is found around 40–50°N, and a meridional heat transport of 0.59 petawatt (PW, 1 PW = 1015 W) is found at 40°N (0.23 PW at 60°N) so that on average ~50 W/m2 is exported from ocean to atmosphere to feed the atmospheric storm track. The zonally averaged flow (the overturning) falls short of explaining the observed heat transport, and the barotropic component of the circulation accounts for up to 50% of the heat transport poleward of 55°N. With the rising Argo float database, the method offers high potential to reconstruct the World Ocean time mean circulation and its heat transport away from the equator at higher resolution. The drawback is that it requires in some critical places additional current observations on the shallow shelves that are not sampled by the Argo floats.
The Influence of Foreland Structures on Hinterland Cooling: Evaluating the Drivers of Exhumation in the Eastern Bhutan Himalaya
Authors: McQuarrie Nadine , Eizenhöfer Paul R. , Long Sean P. , Tobgay Tobgay , Ehlers Todd A. , Blythe Ann E. , Morgan Leah E. , Gilmore Michelle E. , Dering Gregory M.
Published: July 2019

Understanding, and ideally quantifying, the relative roles of climatic and tectonic processes during orogenic exhumation is critical to resolving the dynamics of mountain building. However, vastly differing opinions regarding proposed drivers often complicate how thermochronometric ages are interpreted, particularly from the hinterland portions of thrust belts. Here we integrate three possible cross‐section geometries and kinematics along a transect through the eastern Bhutan Himalaya with a thermal model (Pecube‐D) to calculate the resulting thermal field and predict potential ages. We compare predicted ages to a suite of new and published cooling ages. Our results argue for ramp‐focused exhumation of the Main Central thrust from 16 to 14 Ma at shortening rates of 40–55 mm/year, followed by slower rates (25 mm/year) during the last 50 km of Main Central thrust displacement and growth of the Lesser Himalayan duplex from 14 to 11 Ma. Emplacement of frontal Lesser Himalayan thrust sheets occurred rapidly (55–70 mm/year) between ~11 and 9 Ma, followed by a decrease in shortening rates to ~10 mm/year during motion on the Main Boundary thrust. Modern shortening rates (17 mm/year) and out‐of‐sequence motion on the Main Boundary thrust from 0.5 Ma to present reproduce the young cooling ages near the Main Boundary thrust. We show that the dominant control on exhumation patterns in a fold‐thrust belt results from the evolution of ramps and emphasize that the geometry and kinematics of structures driving hinterland exhumation need to be evaluated with their linked foreland structures to ensure the viability of the proposed geometry, kinematics, and thus cooling history.
How Diverse Observations Improve Groundwater Models
Authors: Schilling Oliver , Cook Peter , Brunner Philip
Published: July 2019

Including diverse observations of exchange fluxes, tracer concentrations and residence times in groundwater model calibration results in more robust predictions than using only classical observations.
Antibiotics Are Flooding Earth’s Rivers
Authors: Joel Lucas
Published: July 2019

The drugs can lead to drug-resistant bacteria and deadly infections.
Tracking Earth’s Shape Reveals Greater Polar Ice Loss
Authors: Thompson Elizabeth
Published: July 2019

Researchers offer a solution to better track mass changes in ocean water and polar ice.
Hotness and Coldness Indexes Based on the Fahrenheit Scale
Authors: Treacy Michael , Ramirez Christopher , O’Keeffe Michael
Published: July 2019

An undergraduate project redefines the h-index.
AGU Has a Story to Tell
Authors: Hanlon Shane
Published: July 2019

Scientists and communicators are increasingly turning to storytelling as a way to talk about science to all types of audiences.
Mooring and Seafloor Pressure End Point Measurements at the Southern Entrance of the Solomon Sea: Subseasonal to Interannual Flow Variability
Authors: Anutaliya Arachaporn , Send Uwe , Sprintall Janet , McClean Julie L. , Lankhorst Matthias , Koelling Jannes
Published: July 2019

Variability of the flow across the Solomon Sea's southern entrance was examined using end point subsurface moorings and seafloor pressure sensors, reconstructed velocity profiles based on satellite‐derived surface velocity and bottom pressure‐derived subsurface velocity, and 1993–2017 proxy volume transport based on satellite altimetry. The reconstructed velocity correctly represents the fluctuating surface flow and subsurface core providing a high‐frequency continuous observing system for this sea. The mean equatorward volume transport over 0‐ to 500‐m depth layer is 15.2 Sv (1 Sv ≡ 106 m3/s) during July 2012 to May 2017. The measurements resolve the full spectrum of the volume transport including energetic subseasonal variability that fluctuates by as much as 25 Sv over one week. At low‐frequency timescales, the study finds that linear Rossby waves forced by Ekman pumping in the interior of the Pacific influence not only seasonal fluctuations as found by previous studies but also interannual variability. As found previously, the El Niño–Southern Oscillation highly influences interannual volume transport. During the 2015/2016 El Niño, observations show the seasonal cycle to be suppressed from the second half of 2014, prior to the mature phase of the El Niño, to September 2016 along with an increase in across‐transect transport. At subseasonal timescales, local Ekman pumping and remote wind stress curl are responsible for a third of the subseasonal variance. The study highlights the importance of high‐frequency observations at the southern entrance of the Solomon Sea and the ability of a linear Rossby model to represent the low‐frequency variability of the transport.
Assessing the Seasonal Dynamics of Nitrate and Sulfate Aerosols at the South Pole Utilizing Stable Isotopes
Authors: Walters Wendell W. , Michalski Greg , Böhlke J. K. , Alexander Becky , Savarino Joël , Thiemens Mark H.
Published: July 2019

Atmospheric nitrate (NO3− = particulate NO3− + gas‐phase nitric acid [HNO3]) and sulfate (SO42−) are key molecules that play important roles in numerous atmospheric processes. Here, the seasonal cycles of NO3− and total suspended particulate sulfate (SO42−(TSP)) were evaluated at the South Pole from aerosol samples collected weekly for approximately 10 months (26 January to 25 October) in 2002 and analyzed for their concentration and isotopic compositions. Aerosol NO3− was largely affected by snowpack emissions in which [NO3−] and δ15N(NO3−) were highest (49.3 ± 21.4 ng/m3, n = 8) and lowest (−47.0 ± 11.7‰, n = 5), respectively, during periods of sunlight in the interior of Antarctica. The seasonal cycle of Δ17O(NO3−) reflected tropospheric chemistry year‐round with lower values observed during sunlight periods and higher values observed during dark periods, reflecting shifts from HOx‐ to O3‐dominated oxidation chemistry. SO42−(TSP) concentrations were highest during austral summer and fall (86.7 ± 73.7 ng/m3, n = 18) and are indicated to be derived from dimethyl sulfide (DMS) emissions, as δ34S(SO42−)(TSP) values (18.5 ± 1.0‰, n = 10) were similar to literature δ34S(DMS) values. The seasonal cycle of Δ17O(SO42−)(TSP) exhibited minima during austral summer (0.9 ± 0.1‰, n = 5) and maxima during austral fall (1.3 ± 0.3‰, n = 6) and austral spring (1.6 ± 0.1‰, n = 5), indicating a shift from HOx‐ to O3‐dominated chemistry in the atmospheric derived SO42− component. Overall, the budgets of NO3− and SO42−(TSP) at the South Pole were complex functions of transport, localized chemistry, biological activity, and meteorological conditions, and these results will be important for interpretations of oxyanions in ice core records in the interior of Antarctica.
Magmatism Along Lateral Slab Edges: Insights From the Diamante‐Enotrio‐Ovidio Volcanic‐Intrusive Complex (Southern Tyrrhenian Sea)
Authors: De Ritis R. , Pepe F. , Orecchio B. , Casalbore D. , Bosman A. , Chiappini M. , Chiocci F. , Corradino M. , Nicolich R. , Martorelli E. , Monaco C. , Presti D. , Totaro C.
Published: July 2019

Volcanic‐intrusive complexes often formed along lateral slab edges as a consequence of subduction‐induced mantle flow. We investigate this process in the southern Tyrrhenian Sea by integrating multibeam bathymetry, seismic‐reflection data, regional magnetic anomalies data, and seismological data. The interpretation of the data highlights the presence of magmatic intrusions that locally reach the seafloor forming volcanic edifices. Chimneys, lava flows, and laccoliths are observed beneath and surrounding the volcanoes. The emplacement and cooling of the magma occurred during the Brunhes Chron. The volcanoes are not active even if the hydrothermal activity occurs. The volcanic‐intrusive complex can be subdivided in a western domain (Diamante and Enotrio seamounts) where strike‐slip transpressional faults deform the volcanic edifices and an eastern domain (Ovidio volcanic seamounts) characterized by flat‐topped volcanic edifices. The flat‐topped morphology is the result of the interplay between volcanism, erosion, sedimentation, and sea‐level change. The Ovidio volcanic seamounts formed in an area that experienced at least 60 m of subsidence. Magnetic signatures over the northern side of the Ovidio and Diamante seamounts highlight the presence of a deep‐rooted, magnetized feeding system remnant. Volcanic edifices extend above a magma feeding system, characterized by low Vp/Vs ratios. The Diamante‐Enotrio‐Ovidio volcanic‐intrusive complex formed as a consequence of the ascent of subduction‐induced mantle flow originated in the northern‐western edge of the retreating Ionian slab. We speculate that the magma ascent was controlled by a strike‐slip deformation belt, which accommodated the bulk of the shear strain resulting from the formation of a roughly E‐W trending, Subduction‐Transform Edges Propagator fault.
A highly colorimetric and ratiometric fluorescent probe for the detection of fluoride ions using test strips
Authors: Shi Junwei , Shu Wei , Wu Yulong , Jing Jing , Zhang Rubo , Zhang Xiaoling
Published: July 2019

In this work, a colorimetric and ratiometric chemosensor NP-OTBDPS, 4-(tert-butyldiphenylsilyloxy)-N-butyl-naphthalimide, was designed and synthesized.
Antihyperglycemic and antihyperlipidemic activities of a polysaccharide fromPhysalis pubescensL. in streptozotocin (STZ)-induced diabetic mice
Authors: Chen Xiaoyong , Li Xiong , Zhang Xiaobo , You Lijun , Cheung Peter Chi-Keung , Huang Riming , Xiao Jianbo
Published: July 2019

PP (Mw= 20.0 kDa) could effectively regulate glucose and lipid metabolism in diabetic mice, and is composed of Glc, Gal and Ara.
Altered carbon assimilation and cellulose accessibility to maximize bioethanol yield under low-cost biomass processing in corn brittle stalk
Authors: Wu Leiming , Feng Shengqiu , Deng Jun , Yu Bin , Wang Youmei , He Boyang , Peng Hao , Li Qian , Hu Ruofei , Peng Liangcai
Published: July 2019

Altered carbon assimilation and cellulose accessibility to maximize bioethanol yield under low-cost biomass processing in corn brittle stalk.
Telopeptide-dependent xenogeneic collagen co-assembly
Authors: Wei Benmei , Wang Linjie , Zhong Huaying , Zhang Juntao , Xu Chengzhi , Xu Yuling , He Lang , Li Sheng , Wang Haibo
Published: July 2019

The function of telopeptide in xenogeneic collagen co-assembly was shown.
Hyperbranched phosphorus flame retardants: multifunctional additives for epoxy resins
Authors: Battig Alexander , Markwart Jens C. , Wurm Frederik R. , Schartel Bernhard
Published: July 2019

Novel phosphorus-based hyperbranched polymers provide multifunctional flame retardancy to epoxy resins.
The debut of chiral cyclic (alkyl)(amino)carbenes (CAACs) in enantioselective catalysis
Authors: Pichon Delphine , Soleilhavoup Michele , Morvan Jennifer , Junor Glen P. , Vives Thomas , Crévisy Christophe , Lavallo Vincent , Campagne Jean-Marc , Mauduit Marc , Jazzar Rodolphe , Bertrand Guy
Published: July 2019

Cyclic (alkyl)(amino)carbene (CAAC) metal complexes can also engage in asymmetric transformations, thereby expanding the toolbox of available chiral carbene ligands.
Switchable modulation of bacterial growth and biofilm formation based on supramolecular tripeptide amphiphiles
Authors: Chen Limin , Yang Dan , Feng Jie , Zhang Min , Qian Qiuping , Zhou Yunlong
Published: July 2019

A minimalistic dual-responsive supramolecular tripeptide system was developed for switchable control of bacterial growth and biofilm formation.
A low-cost strategy to synthesize MnO nanorods anchored on 3D biomass-derived carbon with superior microwave absorption properties
Authors: Hu Peitao , Dong Shun , Li Xiutao , Chen Jingmao , Zhang Xinghong , Hu Ping , Zhang Shengsen
Published: July 2019

Herein, we present a low-cost strategy to synthesize MnO nanorods anchored on 3D biomass-derived carbon with superior microwave absorption properties.
Data‐driven online temperature compensation for robust field‐oriented torque‐controlled induction machines
Authors: Phuc Pieter Nguyen , Vansompel Hendrik , Bozalakov Dimitar , Stockman Kurt , Crevecoeur Guillaume
Published: July 2019

Squirrel‐cage induction machines (IMs) with indirect field‐oriented control are widely used in industry and are frequently chosen for their accurate and dynamic torque control. During operation, however, temperature rises leading to changes in machine parameters. The rotor resistance, in particular, alters, affecting the accuracy of the torque control. The authors investigated the effect of a rotor resistance parameter mismatch in the control algorithm on the angular rotor flux misalignment and the subsequent deviation of stator currents and motor torque from their setpoints. Hence, an online, data‐driven torque compensation to eliminate the temperature effect is proposed to enable robust torque‐controlled IMs. A model‐based analysis and experimental mapping of the temperature effect on motor torque is presented. A temperature‐torque lookup‐table is subsequently implemented within the control algorithm demonstrating the ability to reduce the detrimental effect of temperature on torque control. Experimental results on a 5.5 kW squirrel‐cage induction motor show that the proposed data‐driven online temperature compensation method is able to reduce torque mismatch when compared to having no temperature compensation. Up to 17% torque mismatch is reduced at nominal torque and even up to 23% at torque setpoints that are lower than 20% of the nominal torque. A limited torque error of <1% remains in a broad operating range.
Boundary protection for series‐compensated transmission lines
Authors: Qi Xuanwei , Ye Yu Tian , Wang Song , Lu Chengyu , Xuan XiaoHua , Wen Minghao
Published: July 2019

This study proposes a novel boundary protection for the series‐compensated transmission lines, on the basis of the R–L differential‐equation algorithm using the least square method and the theory of equal transfer process of transmission lines. This method takes the series capacitor (SC) as a boundary. The relative position of the fault with respect to the SC can be determined according to the fitting error of the least square method. This proposed protection method only uses one‐terminal measurement, and the protection reach can be expanded to the total length of the series compensated line. The overreaching problem of the conventional distance relay in the series compensated transmission lines can be effectively overcome. A variety of PSCAD/EMTDC simulation tests show the validity of this new method.
Auto‐correlation‐based Islanding detection technique verified through hardware‐in‐loop testing
Authors: Makwana Yogesh M. , Bhalja Bhavesh R. , Gokaraju Ramakrishna
Published: July 2019

This study describes a novel Islanding detection technique based on a discrimination factor (DF) which is derived from an auto‐correlation factor (ACF) of the voltage signals acquired from the terminal of the distributed generator. The value of DF is calculated from the most affected lags of the ACF during various Islanding and non‐Islanding conditions. Further, the validation of the presented scheme has been carried out by developing a hardware‐in‐loop laboratory setup. In this setup, a power distribution network has been modelled on a real‐time digital simulator (RTDS/RSCAD) which is physically connected to the digital signal processor controller. Various non‐Islanding and Islanding test scenarios have been generated. The proposed ACF‐based technique is able to differentiate Islanding state with non‐Islanding states even for perfect power equilibrium situation. The proposed approach can determine the Islanding state in a period of three cycles from the inception of Islanding. Finally, a relative assessment of the above algorithm with other existing methods shows its supremacy in terms of better stability during critical non‐Islanding situations and lower non‐detection zone in case of Islanding states.
Analytical model of AC contactors for studying response mechanism to multi‐dimensional voltage sag characteristics and its novel applications
Authors: Xiao Xianyong , He Hanyang , Wang Ying
Published: July 2019

The sensitivity of AC contactor (ACC) to voltage sag leads to unnecessary tripping of the motors, resulting in huge economic losses to users. The purpose of this study is to reveal the response mechanism of ACC's behaviour to multi‐dimensional voltage sag characteristics theoretically, based on the analytical model proposed here, and some suggestions are provided to reduce the impact of unnecessary tripping events. First, an analytical model of ACC to sag has proposed and its effectiveness is proven by the laboratory test results. Based on the proposed model, the response mechanism of ACC to voltage sags has been investigated analytically considering the characteristics of voltage sag, including duration, voltage magnitude, point on wave, and phase angle jump. The impact of fault criterion, the practical way to a quick evaluation of the sag immunity of ACC, and the immunity improvement schemes to reduce the unnecessary tripping events by the offline and online way is also discussed here.
Network reconfiguration for the DG‐integrated unbalanced distribution system
Authors: Gangwar Priyanka , Singh Sri Niwas , Chakrabarti Saikat
Published: July 2019

Distribution system reconfiguration is a complex combinatorial optimisation problem. Finding a globally optimal solution to this problem in a short span of time is a challenging task. Two different network reconfiguration methodologies, namely a look‐up table‐based algorithm and a Pareto‐optimisation‐based algorithm have been discussed. Power loss minimisation and reliability maximisation are taken as objectives for both the methodologies when the system is in the normal operating state. The same algorithms also work for maximum service restoration under the post‐fault condition. For reliability assessment in the presence of distributed generators (DGs), an algorithm is also proposed using the probabilistic model of components. In the other algorithm, reconfiguration is performed in the presence of DGs using a look‐up table. The look‐up table is prepared with the help of the proposed Pareto‐optimisation‐based reconfiguration algorithm to train the system for various loading conditions. The feasibility and effectiveness of the proposed methods are demonstrated using the IEEE 34‐ and IEEE 123‐bus unbalanced radial distribution systems under normal and faulty conditions. The algorithms are also tested on a 13‐bus practical distribution system in the field.
Combined analysis of distribution‐level PMU data with transmission‐level PMU for early detection of long‐term voltage instability
Authors: Ghalei Monfared Zanjani Mohsen , Mazlumi Kazem , Kamwa Innocent
Published: July 2019

In the present study, a new method is proposed for early voltage instability detection based on the statistical analysis of the data obtained from PMUs and micro‐PMUs. Although, the use of high sampling rate measurements helps operators to assess the dynamic behavior of the systems, but it may lead to processing a large volume of data, which is a main challenge in this regard. Here, K‐Medoid partitioning method is used for clustering and reducing the computational burden. Clustering is done based on the analysis of the voltage magnitude variance in unstable scenarios. Based on the critical slowing down phenomenon, the voltage magnitude variance in the critical transmission‐level busbars and in the power plant busbars are used as instability detection indices. The data measured by PMUs give information about severity of the events, and micro‐PMUs data provide information on operating status of the over‐excitation limiters as well as the resiliency of network to keep voltage. In different conditions of the Nordic test system, all contingencies are considered for data training. Efficiency of the proposed method for early detection of instability in online operation is evaluated by AdaBoost algorithm, and the obtained results are compared by those of other classifiers.
Long short‐term memory and convolutional neural network for abnormal driving behaviour recognition
Authors: Jia Shuo , Hui Fei , Li Shining , Zhao Xiangmo , Khattak Asad J.
Published: July 2019

Abnormal driving behaviours, such as rapid acceleration, emergency braking, and rapid lane changing, bring great uncertainty to traffic, and can easily lead to traffic accidents. The accurate identification of abnormal driving behaviour helps to judge the driver's driving style, inform surrounding vehicles, and ensure the road traffic safety. Most of the existing studies use clustering and shallow learning, it is difficult to accurately identify the types of abnormal driving behaviours. Aimed at addressing the difficulty of identifying driving behaviour, this study proposed a recognition model based on a long short‐term memory network and convolutional neural network (LSTM‐CNN). The extreme acceleration and deceleration points are detected through the statistical analysis of real vehicle driving data, and the driving behaviour recognition data set is established. By using the data set to train the model, the LSTM‐CNN can achieve a better result.
Composition‐induced non‐ergodic–ergodic transition and electrocaloric evolution in Pb1−1.5x Lax Zr0.8 Ti0.2 O3 relaxor ferroelectric ceramics
Authors: Li Junjie , Yin Ruowei , Su Xiaopo , Li Jianting , Qin Shiqiang , Wei Qiumei , Zhu Mankang , Guo Dong , Qiao Lijie , Bai Yang
Published: July 2019

Relaxor ferroelectrics, with polar nanoregions (PNRs), are good candidates for electrocaloric (EC) refrigeration. This study investigates the EC performance of the Pb1−1.5x Lax Zr0.8 Ti0.2 O3 relaxor ferroelectric ceramics by the direct measurement using a modified differential scanning calorimeter. All the ceramics exhibit pure perovskite phase with a dense microstructure. The results indicate that the increasing La substitution strengthens the relaxor behaviour, promotes the transition from non‐ergodic to ergodic state, and enhances the thermal stability of EC property (instability η  < 16% within 0–140°C for x  = 0.09). While the EC peak widens and shifts to lower temperatures, the peak value decreases from ΔT max  = 0.98 K (@140°C) for x  = 0.06 to ΔT max  = 0.25 K (@40°C) for x  = 0.09 under an electric field of 40 kV/cm. Moreover, the ceramics with x  = 0.07, near the non‐ergodic–ergodic state boundary, show the optimised room temperature EC performance, i.e. ΔT  = 0.41 K (@20°C) and η  < 20% within a wide temperature range of 0–80°C. This work provides an effective material design approach for EC refrigeration in different application conditions.
Design and analysis of an optical camera communication system for underwater applications
Authors: Akram Muhammed , Godaliyadda Roshan , Ekanayake Parakrama
Published: July 2019

The growing interest in underwater explorations has stimulated considerable interest in advancing the enabling technologies of underwater wireless communication (UWC) systems. The study presents the design and implementation techniques of a short‐range unidirectional UWC system which uses optical camera communication (OCC) principles. OCC systems have light emitting diodes at the transmitter, with the receiver being a camera. Overall system design considerations, synchronisation and frame selection, and a novel spatial position‐based image processing algorithm to decode data from frames are discussed. Also, the optimisation techniques used in the image processing algorithm are also elaborated. Importance of few of key features of an OCC system, namely camera quality, transmission distance and the threshold value used for image binarisation are demonstrated through numerical results using simulations via synthetically generated images. Further, the bit error rate (BER) performance of the system is evaluated using the experimental proof of concept setup in clear water, muddy water and under turbulence conditions. Overall BER performance in the order of within the communication distance of 1 m is observed, and it shows that the proposed system design and algorithms can be used to realise an UWC link for short‐range applications successfully.
Joint detection and tracking algorithm for cognitive radar based on parallel structure of EKF and particle filter
Authors: Wang Shuliang , Bi Daping , Li Jianping , Zhang Yanqiu
Published: July 2019

In order to reduce the uncertainty of radar manoeuvring target tracking (RMTT) in cluttered background, a joint detection and tracking algorithm based on cognitive radar is proposed. First, a prism structure resolution cell of time‐delay, Doppler and azimuth is designed. Then, an approximate expression of measurement error covariance including waveform and detection threshold parameters is given. Then, based on the idea of human brain perception‐action cycle, a joint waveform and detection threshold adaptive tracking algorithm based on minimum information entropy criterion is proposed. Finally, a cognitive structure adaptive particle filter (CSAPF) algorithm, based on parallel structure of extended Kalman filter (EKF) and particle filter, are used with Probabilistic Data Association (PDA) algorithm for RMTT. During the process, CSAPF‐PDA can always obtain the best tracking performance with the minimum number of particle samples, thus effectively taking into account the tracking accuracy and efficiency. The effectiveness of the proposed algorithm is verified by simulation experiments.
Distributed temperature sensing in OPGW with multiple optical fibres
Authors: Carvalho Renatto V. , Bonfim Márlio Jose do Couto , Ussuna Daniel A. , Toledo Luiz F.R.B. , Martins Rafael , Filho Vitoldo S.
Published: July 2019

The ampacity of a material is defined as its maximum electrical current capacity. In an overhead transmission line, it is related to the maximum sag that does not compromise its safe operation. As the sag depends on the conductor's temperature, with this parameter it is possible to estimate its ampacity, increasing the efficiency of the electrical system via real‐time energy dispatch management. With the Brillouin backscattering phenomena, the distributed temperature measurement in the fibre inside the optical ground wire (OPGW) or optical phase conductor is possible. However, it is common for overhead power transmission lines to be composed by more than one optical fibre. A calibration algorithm was developed to enable the application of a distributed temperature sensing equipment to monitor the temperature of an OPGW with more than two different fibres. The 230 kV Ibiporã‐Londrina Transmission Line was used as a case study, being approximately 20 km long and composed of three different fibres spliced in series along with its extension. Through comparison with calibrated sensors, the technique and algorithm were validated. It was possible to characterize the system and perform the temperature monitoring with a spatial resolution of 1 m and amplitude error of less than 6°C.
Novel priori‐knowledge‐free manoeuvring target‐tracking method
Authors: Guo Jin‐Peng , Liu Quan‐Hua , Xu Jia
Published: July 2019

In the past few decades, many manoeuvring target‐tracking methods have been proposed. However, most of these methods require some priori knowledge about the target, which is hard to obtain in many scenarios. Here, a priori‐knowledge‐free (PKF) manoeuvring target‐tracking method is proposed by introducing a time‐varying polynomial‐function‐based motion model. The model order and coefficients are real‐time estimated to guarantee a steady performance in both manoeuvring and non‐manoeuvring situations. Numerical results are provided to validate the effectiveness of the proposed method.
Broadband direction of arrival estimation via spatial co‐prime sampling and polynomial matrix methods
Authors: Coventry William , Clemente Carmine , Soraghan John
Published: July 2019

Direction of arrival estimation is a crucial aspect of many active and passive systems, including radar and electronic warfare applications. Spread spectrum modulation schemes are becoming ever more common in both Radar and Communications systems; because such modulation spreads the signal energy in frequency and time, such sources prompt the need for new approaches for detection and location. Broadband antennas and their subsequent signal processing systems are expensive in terms of both cost and power consumption. This forces a limitation on the number of elements in a feasible real‐world array. In this paper, a novel co‐prime broadband MUSIC‐based direction of arrival algorithm is presented. The main feature of the new method is that it aims to reduce the number of antenna elements for a given aperture by utilising a co‐prime sensing scheme applied to the problem of broadband direction finding via the polynomial MUSIC algorithm. Comparative results using simulated data show that the proposed co‐prime polynomial MUSIC has comparable performance to those obtained using a uniform linear array method with an equivalent physical aperture.
Sparsity‐driven bandwidth factorisation autofocus of high‐resolution squint SAR imagery reconstructed by FFBP
Authors: Wang Xin , Sun Xiaoxiao
Published: July 2019

In large squint high‐resolution cases, smearing introduced by path deviation and air turbulence in synthetic aperture radar (SAR) imagery reconstructed via fast factorised backprojection algorithm (FFBP) will exist along space variant oblique angles. To refocus the blurred FFBP imagery, a motion phase error estimation and compensation methodology based on range bandwidth factorisation is proposed in this study. Motion phase error is estimated based on lower resolution data and then sparsity‐driven combination is performed to derive the high‐resolution refocused imagery. Extended point target simulation can verify the bandwidth‐factorisation‐based autofocus algorithm.
An improved inverse synthetic aperture radar range alignment method based on maximum contrast
Authors: Li Yong , Zhang Tianyi , Ding Zegang , Gao Wenbin , Chen Jing
Published: July 2019

Inverse synthetic aperture radar (ISAR) is an important tool for non‐cooperative ship imaging, and one key step of ISAR imaging is range alignment. To achieve the range alignment with high precision, efficiency and robustness, an improved ISAR range alignment method based on maximum contrast is proposed in this paper, which takes the maximum contrast of average range profile as the optimisation criterion to perform the range alignment. Compared with the minimum entropy method, this method is with lower computation complexity and faster convergence rate. Thus the method proposed in this article is more effective and more robust. Computer simulation and real data experiment validate the effectiveness and robustness of the proposed method.
Doppler beam sharpening/ground moving target indication techniques based on space–time adaptive processing for airborne active phased array fire‐control radar
Authors: Li Xiaoming , Gao Wei , Han Xiaodong
Published: July 2019

In order to improve the angle accuracy and meet the requirement of side‐lobe blanking, the fire‐control radar system usually adopts sum beam, azimuth difference beam, elevation difference beam and several protecting antennas simultaneously. A ΣΔG‐STAP method based on sum, difference and protecting channels is proposed to improve the performance of ground moving target detection. Moreover, the target is located on the Doppler beam sharpening image by the monopulse angle estimation technique. The effectiveness of the proposed method is verified using the simulated data and measured data.