bluuebunny/crossref_metadata_2025 huggingface dataset:
Design for multi-step mechanochromic luminescence property by enhancement of environmental sensitivity in a solid-state emissive boron complex
Authors: Saotome Satoru , Suenaga Kazumasa , Tanaka Kazuo , Chujo Yoshiki
Published: April 2020

The solid-state emissive boron complex with multi-step mechanochromic luminescence was designed. The crystalline sample showed gradual changes in luminescent color triggered by scratching. The design concept is illustrated.
Experimental study on the kinetic effect of N-butyl-N-methylpyrrolidinium tetrafluoroborate and poly(N-vinyl-caprolactam) on CH4 hydrate formation
Authors: Ren Jun-Jie , Lu Zhi-Lin , Long Zhen , Liang Deqing
Published: April 2020

The kinetic inhibition performance of N-butyl-N-methylpyrrolidinium tetrafluoroborate ([BMP][BF4]), poly(N-vinylcaprolactam) (PVCap) and compound inhibitor systems on methane hydrate were studied from both macroscopic and microscopic perspectives.
Messenger RNA/polymeric carrier nanoparticles for delivery of heme oxygenase-1 gene in the post-ischemic brain
Authors: Oh Jungju , Kim Sang-Mi , Lee Eun-Hye , Kim Minkyung , Lee Youngki , Ko Seung Hwan , Jeong Ji Hoon , Park Chang-Hwan , Lee Minhyung
Published: April 2020

Heme oxygenase-1 messenger RNA (HO1-mRNA) was delivered into the post-ischemic brain, using a polymeric carrier. Therapeutic efficacy of HO1-mRNA delivery was compared with that of HO1-plasmid DNA (HO1-pDNA) in ischemia-reperfusion rat models.
An engineered exosome for delivering sgRNA:Cas9 ribonucleoprotein complex and genome editing in recipient cells
Authors: Ye Yangyang , Zhang Xiang , Xie Fei , Xu Bin , Xie Ping , Yang Ting , Shi Qian , Zhang Chen-Yu , Zhang Yujing , Chen Jiangning , Jiang Xiaohong , Li Jing
Published: April 2020

CRISPR-Cas9 components delivered by engineered exosomes achieve genome editing in recipient cells.
Synthesis, structural characterization and electrochemical and magnetic studies of M(hfac)2 (M = CuII, CoII) and Nd(hfac)3 complexes of 4-amino-TEMPO
Authors: Navarro Yolanda , Guedes Guilherme P. , Cano Joan , Ocón Pilar , Iglesias María José , Lloret Francisco , López-Ortiz Fernando
Published: April 2020

Five 4-amino-TEMPO–M(hfac)n (M = CuII, CoII, NdIII) complexes with unprecedented structures are reported, together with their electrochemical and magnetic properties.
Photochemical fate of quaternary ammonium compounds in river water
Authors: Hora Priya I. , Arnold William A.
Published: April 2020

The photochemical fate of quaternary ammonium compounds in surface water is largely influenced by reaction with hydroxyl radicals.
Effect of antimicrobial washout from anaerobic digesters on microbial community composition
Authors: Kappell Anthony D. , Carey Daniel E. , Zitomer Daniel H. , McNamara Patrick J.
Published: April 2020

Differences in abundance of genera key to methanogenesis and anaerobic digestion persist after antimicrobial washout.
Synthesis, evaluation and molecular modelling of piceatannol analogues as arginase inhibitors
Authors: Muller J. , Cardey B. , Zedet A. , Desingle C. , Grzybowski M. , Pomper P. , Foley S. , Harakat D. , Ramseyer C. , Girard C. , Pudlo M.
Published: April 2020

A quantum chemistry guided optimisation (leading to piceatannol analogue3t) with a good understanding of the catechol binding mode to the bimanganese cluster of arginase.
Soluble poly(4-fluorostyrene): a high-performance dielectric electret for organic transistors and memories
Authors: Zhu Yuanwei , Fan Yongkang , Li Shengtao , Wei Peng , Li Dongfan , Liu Bo , Cui Dongmei , Zhang Zhicheng , Li Guochang , Nie Yongjie , Lu Guanghao
Published: April 2020

Poly(4-fluorostyrene) with strong charge storage capability is introduced as an electret in a field-effect transistor to improve device performance and memory stability.
Stabilizing sulfur vacancy defects by performing “click” chemistry of ultrafine palladium to trigger a high-efficiency hydrogen evolution of MoS2
Authors: Liu Suli , Zhou Liangliang , Zhang Wanjia , Jin Junyu , Mu Xueqin , Zhang Sudi , Chen Changyun , Mu Shichun
Published: April 2020

A “click” chemistry strategy is used to construct an all-pH efficient hydrogen evolution reaction (HER) catalyst with engineered unsaturated sulfur edges via a strong coupling effect between ultrafine Pd ensembles and Co-MoS2 nanosheets.
Progress in the functional modification of graphene/graphene oxide: a review
Authors: Yu Wang , Sisi Li , Haiyan Yang , Jie Luo
Published: April 2020

Graphene and graphene oxide have attracted tremendous interest over the past decade due to their unique and excellent electronic, optical, mechanical, and chemical properties.
Phosphate-sensing with (di-(2-picolyl)amino)quinazolines based on a fluorescence on–off system
Authors: Aoki Kazusa , Osako Ryuji , Deng Jiahui , Hayashita Takashi , Hashimoto Takeshi , Suzuki Yumiko
Published: April 2020

Supramolecular probe Cu-dpa-QZ2/FPB-γ-CyD recognized ATP with high sensitivity.
Ultrafast broadband nonlinear optical properties and excited-state dynamics of two bis-chalcone derivatives
Authors: Shen Lei , Li Zhongguo , Wu Xingzhi , Zhou Wenfa , Yang Junyi , Song Yinglin
Published: April 2020

The introduction of a benzene ring largely affects the excited-state absorption spectra and dynamics of these chromophores.
Synthesis of nano-sized tungsten oxide particles encapsulated in a hollow silica sphere and their photocatalytic properties for decomposition of acetic acid using Pt as a co-catalyst
Authors: Harada Takashi , Yagi En , Ikeda Shigeru
Published: April 2020

We present a procedure for the synthesis of WO3 nanoparticles encapsulated in a hollow silica sphere, and their unique photocatalytic properties.
Synergistic effect of potassium iodide and sodium dodecyl sulfonate on the corrosion inhibition of carbon steel in HCl medium: a combined experimental and theoretical investigation
Authors: Tan Jianhong , Guo Lei , Yang Hong , Zhang Fan , El Bakri Youness
Published: April 2020

Carbon steel is an important industrial material, but it usually suffers from serious corrosion in the service environment.
Impact of surface coating on electrochemical and thermal behaviors of a Li-rich Li1.2Ni0.16Mn0.56Co0.08O2 cathode
Authors: Nisar Umair , Petla Ramesh , Jassim Al-Hail Sara Ahmad , Quddus Aisha Abdul , Monawwar Haya , Shakoor Abdul , Essehli Rachid , Amin Ruhul
Published: April 2020

ZrO2 coated Li1.2Ni0.16Mn0.56Co0.08O2 (NMC) materials with improved electrochemcial performance.
Fabrication of magnetic iron oxide-supported copper oxide nanoparticles (Fe3O4/CuO): modified screen-printed electrode for electrochemical studies and detection of desipramine
Authors: Tajik Somayeh , Beitollahi Hadi , Aflatoonian Mohammad Reza , Mohtat Bita , Aflatoonian Behnaz , Shoaie Iran Sheikh , Khalilzadeh Mohammad A. , Ziasistani Marzieh , Zhang Kaiqiang , Jang Ho Won , Shokouhimehr Mohammadreza
Published: April 2020

The present investigation examines a sensitive electrochemical technique to detect desipramine through Fe3O4/CuO nanoparticles.
Hybrid fluorescent liquid crystalline composites: directed assembly of quantum dots in liquid crystalline block copolymer matrices
Authors: Bugakov Miron , Abdullaeva Sharifa , Samokhvalov Pavel , Abramchuk Sergey , Shibaev Valery , Boiko Natalia
Published: April 2020

Spatial distribution of QDs within hybrid composite films was programed by varying the molecular architecture of the host LC block copolymers.
Influence of channel height on mixing efficiency and synthesis of iron oxide nanoparticles using droplet-based microfluidics
Authors: Kašpar O. , Koyuncu A. H. , Hubatová-Vacková A. , Balouch M. , Tokárová V.
Published: April 2020

Experimental and CFD numerical analysis of mixing efficiency in droplet-based microfluidics for various channel heights and its impact on the preparation of iron oxide nanoparticles.
In situ Raman study of the photoinduced behavior of dye molecules on TiO2(hkl) single crystal surfaces
Authors: Zhang Sheng-Pei , Lin Jia-Sheng , Lin Rong-Kun , Radjenovic Petar M. , Yang Wei-Min , Xu Juan , Dong Jin-Chao , Yang Zhi-Lin , Hang Wei , Tian Zhong-Qun , Li Jian-Feng
Published: April 2020

In dye-sensitized solar cells (DSSCs), the TiO2/dye interface significantly affects photovoltaic performance.
Coordination polymer glass from a protic ionic liquid: proton conductivity and mechanical properties as an electrolyte
Authors: Ogawa Tomohiro , Takahashi Kazuki , Nagarkar Sanjog S. , Ohara Koji , Hong You-lee , Nishiyama Yusuke , Horike Satoshi
Published: April 2020

A proton-conducting coordination polymer glass derived from a protic ionic liquid works as a moldable solid electrolyte and the anhydrous fuel cell showedI–Vperformance of 0.15 W cm−2at 120 °C.
Influence of hydrogen and oxygen on the structure and properties of sputtered magnesium zirconium oxynitride thin films
Authors: Kim Jekyung , Bauers Sage R. , Khan Imran S. , Perkins John , Park Bo-In , Talley Kevin R. , Kim Daehan , Zakutayev Andriy , Shin Byungha
Published: April 2020

Nitride materials with mixed ionic and covalent bonding character and resulting good charge transport properties are attractive for optoelectronic devices.
Synthesis and electrochemical properties of 2D molybdenum vanadium carbides – solid solution MXenes
Authors: Pinto David , Anasori Babak , Avireddy Hemesh , Shuck Christopher E. , Hantanasirisakul Kanit , Deysher Grayson , Morante Joan Ramon , Porzio William , Alshareef Husam N. , Gogotsi Yury
Published: April 2020

MXenes demonstrate high performance in energy storage. We report the synthesis and electrochemical characterization of a novel MXene, MoxV4−xC3.
P–Fe bond oxygen reduction catalysts toward high-efficiency metal–air batteries and fuel cells
Authors: Jin Huihui , Kou Zongkui , Cai Weiwei , Zhou Huang , Ji Pengxia , Liu Bingshuai , Radwan Amr , He Daping , Mu Shichun
Published: April 2020

An Fe, N, P co-doped carbon framework catalyst (CPFeNPC) with a novel C–P–Fe–Nx–P–C system exhibits superior oxygen reduction reaction (ORR) catalytic performance and shines new light on the real application of metal–N–C catalysts in fuel cells.
A highly efficient overall water splitting ruthenium-cobalt alloy electrocatalyst across a wide pH range via electronic coupling with carbon dots
Authors: Feng Tanglue , Yu Guangtao , Tao Songyuan , Zhu Shoujun , Ku Ruiqi , Zhang Ran , Zeng Qingsen , Yang Mingxi , Chen Yixin , Chen Weihua , Chen Wei , Yang Bai
Published: April 2020

Through the modification of the surface and bulk electronic structures of Ru, the developed Ru-based catalyst presents superior electrocatalytic hydrogen and oxygen evolution activities with great durability over a wide pH range.
Nanosized copper(ii) oxide/silica for catalytic generation of nitric oxide from S-nitrosothiols
Authors: Kulyk Kostiantyn , Azizova Liana , Cunningham James M. , Mikhalovska Lyuba , Borysenko Mykola , Mikhalovsky Sergey
Published: April 2020

The findings of this study suggest that copper(ii) oxide–silica nanoparticles produce NO from the GSNO species at physiological conditions in situ and could be used for designing biomedical materials with NO generating activity.
Clickable decellularized extracellular matrix as a new tool for building hybrid-hydrogels to model chronic fibrotic diseases in vitro
Authors: Petrou Cassandra L. , D’Ovidio Tyler J. , Bölükbas Deniz A. , Tas Sinem , Brown R. Dale , Allawzi Ayed , Lindstedt Sandra , Nozik-Grayck Eva , Stenmark Kurt R. , Wagner Darcy E. , Magin Chelsea M.
Published: April 2020

Hydrolytically stable, phototunable hybrid-hydrogels containing clickable decellularized extracellular matrix enable spatiotemporal control over fibroblast activation.
Functional peptide-based drug delivery systems
Authors: Lian Zheng , Ji Tianjiao
Published: April 2020

Representative strategies for designing smart drug delivery systems by using functional peptides in the past few years are highlighted in this review.
Simultaneous enhancement of thermoelectric and mechanical performance for SnTe by nano SiC compositing
Authors: Wang Teng , Wang Hongchao , Su Wenbin , Zhai Jinze , Yakovleva Galina , Wang Xue , Chen Tingting , Romanenko Anatoly , Wang Chunlei
Published: April 2020

SiC is firstly introduced into SnTe. The created lattice mismatch and interfaces via hand milling are responsible for the enhanced zT, which is comparable with doped samples. Besides, the hardness of samples is got improved with SiC compositing.
Neural Indices Mediating Rhyme Discrimination Differ for Some Young Children Who Stutter Regardless of Eventual Recovery or Persistence
Authors: Gerwin Katelyn L. , Weber Christine
Published: April 2020

Purpose

Previous studies of neural processing of rhyme discrimination in 7- to 8-year-old children who stutter (CWS) distinguished children who had recovered, children who had persisted, and children who did not stutter (CWNS; Mohan & Weber, 2015). Here, we investigate neural processing mediating rhyme discrimination for early acquired real words in younger CWS and CWNS (4;1–6;0 years;months), when rhyming abilities are newly emerging, to examine possible relationships toeventualrecovery (CWS-eRec) and persistence in stuttering (CWS-ePer).

Method

Children performed a rhyme discrimination task while their event-related brain potentials were recorded. CWNS, CWS-eRec, and CWS-ePer had similar speech and language abilities. Inclusionary criteria incorporated at least 70% accuracy for rhyme discrimination. Analyses focused on the mean amplitude of the N400 component elicited by rhyming and nonrhyming words in anterior and posterior regions of interest.

Results

CWNS, CWS-eRec, and CWS-ePer displayed a classic event-related potential rhyme effect for rhyme discrimination characterized by larger amplitude, posteriorly distributed N400s elicited by nonrhyming targets compared to rhyming targets. CWNS displayed a more robust anterior rhyme effect compared to the CWS groups with a larger amplitude N400 anteriorly for the rhyming targets. This effect was more consistent across individual CWNS than CWS.

Conclusions

The groups of CWNS, CWS-eRec, and CWS-ePer, who had all developed rhyming discrimination abilities, exhibited similar underlying neural processes mediating phonological processing of early acquired words for the classic central-parietal rhyme effect. However, individual variability of the anterior rhyme effect suggested differences in specific aspects of phonological processing for some CWS-eRec and CWS-ePer compared to CWNS.
Communication Sciences and Disorders PhD Graduates' Perceptions of Their PhD Program
Authors: Crais Elizabeth , Savage Melody Harrison
Published: April 2020

Purpose

The shortage of doctor of philosophy (PhD)–level applicants to fill academic and research positions in communication sciences and disorders (CSD) programs calls for a detailed examination of current CSD PhD educational practices and the generation of creative solutions. The intended purposes of the article are to encourage CSD faculty to examine their own PhD program practices and consider the perspectives of recent CSD PhD graduates in determining the need for possible modifications.

Method

The article describes the results of a survey of 240 CSD PhD graduates and their perceptions of the challenges and facilitators to completing a PhD degree; the quality of their preparation in research, teaching, and job readiness; and ways to improve PhD education.

Results

Two primary themes emerged from the data highlighting the need for “matchmaking.” The first time point of needed matchmaking is prior to entry among students, mentors, and expectations as well as between aspects of the program that can lead to students' success and graduation. The second important matchmaking need is between the actual PhD preparation and the realities of the graduates' career expectations, and those placed on graduates by their employers.

Conclusions

Within both themes, graduate's perspectives and suggestions to help guide future doctoral preparation are highlighted. The graduates' recommendations could be used by CSD PhD program faculty to enhance the quality of their program and the likelihood of student success and completion.

Supplemental Material

https://doi.org/10.23641/asha.11991480
Data filter function incremental mining based on feature selection in an active distribution network
Authors: Deng Song , Cai Qingyuan , Zhang Zi , Yang Lechan , Huang Tinglei , Yuan Changan
Published: April 2020

Compared with traditional distributed networks, the complex access environment, flexible access mode, massive access terminal, and data in an active distribution network will bring great security challenges to data transmission. The existing data security methods, such as access control and encryption, address the security of massive, high dimensional, and non‐text data in the active distribution network. Therefore, feature selection algorithm based on rough set is first given to reduce the complexity of massive and high dimensional data. And then, based on feature selection, the authors propose a data filtering function model mining algorithm by using gene expression programming (DFFM‐FSGEP). Finally, to solve the data filter function model mining of the incremental dataset, they also present an incremental mining algorithm of the filtering function model based on functional fitting (IMFFM‐FF). Experimental results show that the proposed algorithm in this study can greatly reduce the complexity of experimental datasets to be processed, and compared with the other algorithms, DFFM‐FSGEP has higher classification accuracy and sensitivity, and IMFFM‐FF has higher classification speed and classification accuracy for incremental datasets.
Going beyond free viewpoint: creating animatable volumetric video of human performances
Authors: Hilsmann Anna , Fechteler Philipp , Morgenstern Wieland , Paier Wolfgang , Feldmann Ingo , Schreer Oliver , Eisert Peter
Published: April 2020

An end‐to‐end pipeline for the creation of high‐quality animatable volumetric video of human performances is presented. Going beyond the application of free‐viewpoint video, the authors allow re‐animation and alteration of an actor's performance through the enrichment of the captured data with semantics and animation properties. Hybrid geometry‐ and video‐based animation methods are applied that allow a direct animation of the high‐quality data itself instead of creating a CG model that resembles the captured data. Semantic enrichment and animation are achieved by establishing temporal consistency followed by automatic rigging of each 3D frame using a parametric human body model. The hybrid approach combines the flexibility of classical CG animation with the realism of real captured data. For the face, coarse movements are modelled in the geometry only, while very fine and subtle details, often lacking in purely geometric methods, are captured in video textures, which can interactively be combined to form new facial expressions. On top of that, regions that are challenging to synthesise, such as the teeth or the eyes, are learned and filled in realistically in an autoencoder‐based approach. This study covers the full pipeline from capturing, volumetric video production, and enrichment with semantics for the final hybrid animation.
DeepJoint segmentation for the classification of severity‐levels of glioma tumour using multimodal MRI images
Authors: Mahesh K Michael , Renjit J Arokia
Published: April 2020

Brain tumour segmentation is the process of separating the tumour from normal brain tissues. A glioma is a kind of tumour, which fires up in the glial cells of the spine or the brain. This study introduces a technique for classifying the severity levels of glioma tumour using a novel segmentation algorithm, named DeepJoint segmentation and the multi‐classifier. Initially, the brain images are subjected to pre‐processing and the region of interest is extracted. Then, the segmentation of the pre‐processed image is done using the proposed DeepJoint segmentation, which is developed through the iterative procedure of joining the grid segments. After the segmentation, feature extraction is carried out from core and oedema tumours using information‐theoretic measures. Finally, the classification is done by the deep convolutional neural network (DCNN), which is trained by an optimisation algorithm, named fractional Jaya whale optimiser (FJWO). FJWO is developed by integrating the whale optimisation algorithm in fractional Jaya optimiser. The performance of the proposed FJWO–DCNN with the DeepJoint segmentation method is analysed using accuracy, true positive rate, specificity, and sensitivity. The results depicted that the proposed method produces a maximum accuracy of 96%, which indicates its superiority.
Structure–texture image decomposition using a new non‐local TV‐Hilbert model
Authors: Lv Yehu
Published: April 2020

Combining the advantages of the non‐local total variation (TV) and the Gabor function, a new Gabor function based non‐local TV‐Hilbert model is presented to separate the structure and texture components of the image. Computationally, by introducing the dual form of the non‐local TV, the authors reformulate the non‐local TV‐Hilbert minimisation problem into a convex–concave saddle‐point problem. In the aspect of solving algorithm, by transforming the Chambolle–Pock's first‐order primal–dual algorithm into a different equivalent form. The authors propose a proximal‐based primal–dual algorithm to solve the convex–concave saddle‐point problem. At last, experimental results demonstrate that the proposed new model outperforms several existing state‐of‐the‐art variational models.
A bi‐directional fractional‐order derivative mask for image processing applications
Authors: Hacini Meriem , Hachouf Fella , Charef Abdelfatah
Published: April 2020

Fractional computation has been recently designed as a major mathematical tool in image and signal processing fields. This study presents a novel operator established for two‐dimensional fractional differentiation. It is developed based on the one‐dimensional Charef fractional differentiation extension. A new multi‐directional mask is proposed and a new adaptive fractional‐order computation is introduced. The proposed method uses the gradient computation properties. It has been applied in edge detection and de‐noising problems using real and synthetic images. Obtained results have been compared to those given by integer and fractional useful operators. Results demonstrate that the fractional edge images obtained using the proposed operator has more complete and clear contour information and more abundant texture detail information. The performances have been improved by the proposed method.
Bus arrival time prediction and measure of uncertainties using survival models
Authors: Sharmila R.B. , Velaga Nagendra R. , Choudhary Pushpa
Published: April 2020

This study uses survival models to estimate the arrival time of buses at the downstream stops and intersections. Both accelerated failure time (AFT) and Cox regression based hazard models were considered in this study. Two different types of events: (i) buses arriving at bus stops and (ii) buses arriving at signalised intersections were included for measuring arrival times. Weibull and log‐logistic distribution models were fitted for obtaining the arrival times against both the events separately. Various other factors such as distance, speed, bus stop dwell time, passenger count, gradient of the road, intersection length and signal details which included green time, red time, cycle length and so on were considered as explanatory variables. The proposed study was tested on a study corridor of length 59.48 km in the Mumbai arterial roads using public transport (buses). The results reveal that arrival times predicted using the developed models provided smaller uncertainties for 70% of the prediction and reduced prediction variation by 10%. The mean absolute percentage error value obtained for the AFT survival models was 10.04. Overall, the AFT model approach appears to be a promising method compared to Cox regression to predict bus arrival times and the associated uncertainties.
Beam‐steering high‐gain array antenna with FP Bow‐tie slot antenna element for pattern stabilisation
Authors: Rafiei Vahid , Sharifi Ghader , Karamzadeh Saeid , Kartal Mesut
Published: April 2020

In this work, a beam‐steering array antenna for pattern stabilisation is presented. The antenna element consists of two layers with a unique structure of microstrip to coplanar waveguide (CPW) transition to cover a frequency range from 20 to 30 GHz and a stable pattern at all operating frequencies. To increase the gain of the antenna element, an elliptical broadband Fabry–Perot cavity structure is used. The element manages 3 dB gain bandwidth of almost 23–26 GHz with a 14.4 dBi peak. In addition, a modified Butler matrix consisting of two 90° and two 135° couplers without phase shift section is used to attain a stable pattern. The proposed Butler matrix performs a stationary phase with a phase error of less than ±6° over a frequency band from 21 to 29 GHz. The integration of the proposed element and feed network leads to a beam‐tilting antenna capable of managing its patterns through the input ports in the operating frequency range of 20–29.5 GHz (9.5 GHz) and 20.6–29.6 GHz (9 GHz) for ports 1 and 2, respectively.
Cluster oriented resource allocation and power optimisation for D2D network in cellular communications
Authors: Gour Radhika , Tyagi Anshul
Published: April 2020

This work proposes a cluster oriented channel assignment and difference of two convex functions (d.c.) programming based power optimisation algorithm for the downlink device‐to‐device (D2D) communication underlaying cellular networks. The authors' objective is to maximise D2D throughput while protecting the performance of existing cellular users (CUs) whose channel is reused among multiple D2D pairs, by imposing a minimum rate requirement constraint on each CU. The joint channel and power optimisation problem is a mixed integer non‐linear programming problem that is NP‐hard to solve. Therefore, a three stage solution is proposed: cluster formation to minimise the interference among the D2D pairs followed by an optimal channel assignment using the Hungarian algorithm and then an iterative power optimisation algorithm based on d.c. programming. Moreover, the transmission power of base station and D2D users is optimised on the same channel while considering the mutual interference among D2D pairs. Numerical results verify the effectiveness of the proposed resource allocation scheme in terms of the D2D sum rate and the number of successful transmission of D2D users. Moreover, the iterative power optimisation algorithm shows a fast convergence behaviour. In addition to this, the energy efficiency is also analysed with respect to various parameters.
Time delay estimation using wavelet denoising maximum likelihood method for underwater reverberant environment
Authors: Boopathi Rajan Marxim Rahula Bharathi , Mohanty Amiya Ranjan
Published: April 2020

Time delay estimation (TDE) between receivers plays a significant role in various fields such as radar, sonar, global positioning system, and underwater communications. TDE is the first step in the localisation and tracking of the source. Estimation of the time delay of a passive sonar system in a reverberant environment is one of the most challenging tasks. For some decades, the well‐known generalised cross‐correlation (GCC) method has been implemented to estimate the time delay. By using various pre‐filters in the GCC method, the quality of TDE has improved in various cases. In this work, the use of wavelet denoising for TDE in a passive sonar system has been proposed. The proposed method uses the denoised signal in a maximum likelihood estimator in the reverberant environment to estimate the time delay. The proposed method is efficient for the underwater reverberant environment.
Double‐adaptive chirplet transform for radar signature extraction
Authors: Abratkiewicz Karol
Published: April 2020

This study presents a novel method for time–frequency (TF) signal analysis and chirp rate estimation dedicated for electromagnetic spectrum sensing, electronic warfare, electronic intelligence and/or passive bistatic radar purposes in which frequency modulated signals occur. The approach is based on the double‐adaptive chirplet transform, providing optimal analysis window parameters, which is a crucial problem during TF processing. The presented methodology is based on a Gaussian window with two degrees of freedom, which results in a strong concentration of energy on the TF plane around the main component, even if the initial window parameters were mismatched. As an example of the method's usefulness, different types of real‐life radar pulses were processed: firstly, two types of non‐linear frequency‐modulated waveforms were examined as a suitable illustration of the changeability of the analysis window parameters. Secondly, the linear frequency modulated signals were analysed in the presence of strong interference and multipath propagation. The waveforms were processed and compared, creating individual radar signatures, which may allow transmitter classification and signal reconstruction to be carried out in further processing. Moreover, the estimation limitations were compared to the Cramer‐Rao lower bound, and an appendix organising mathematical fundamentals for the analysed methods is provided.
Heuristic approach for transactive energy management in active distribution systems
Authors: Rajasekhar Batchu , Pindoriya Naran M.
Published: April 2020

The advent of distributed energy resources (DERs), which include small conventional and renewable generation units, energy storage, and flexible loads in distribution network needs distributed coordination for effective management. In this paper, a stochastic transactive management framework is proposed to minimize overall cost and avoid network constraints violation at the distribution network level. This framework includes day‐ahead scheduling of electric vehicles and air conditioning loads under demand response aggregators (DRAs), and DERs under distributed generation owners (DGOs) into day‐ahead wholesale market in a network managed by a distribution network operator (DNO). An agent called distribution independent system operator (DISO) is responsible for coordination among DRAs, DGOs, and DNO. A heuristic step‐size update approach is proposed to calculate the Lagrange multiplier iteratively and improve the convergence speed. This framework is modeled as a quadratic constraint programming (QCP) problem and solved using the GAMS solver. Simulation results on a modified 33‐bus system with considerable penetration of loads and DERs, shows that the suggested framework can efficiently reduce the iterations to converge and returns an optimal schedule. And demonstrate the effect of network congestion, demand, and generation uncertainties on the resulting objective values of the agents and magnitude of the Lagrange multiplier values.
Improving spectroscopic lithium abundances
Authors: Mott A. , Steffen M. , Caffau E. , Strassmeier K. G.
Published: April 2020

Context. Accurate spectroscopic lithium abundances are essential in addressing a variety of open questions, such as the origin of a uniform lithium content in the atmospheres of metal-poor stars (Spite plateau) or the existence of a correlation between the properties of extrasolar planetary systems and the lithium abundance in the atmosphere of their host stars.

Aims. We have developed a tool that allows the user to improve the accuracy of standard lithium abundance determinations based on 1D model atmospheres and the assumption of local thermodynamic equilibrium (LTE) by applying corrections that account for hydrodynamic (3D) and non-LTE (NLTE) effects in FGK stars of different metallicity.

Methods. Based on a grid of CO5BOLD 3D models and associated 1D hydrostatic atmospheres, we computed three libraries of synthetic spectra of the lithium λ 670.8 nm line for a wide range of lithium abundances, accounting for detailed line formation in 3D NLTE, 1D NLTE, and 1D LTE, respectively. The resulting curves-of-growth were then used to derive 3D NLTE and 1D NLTE lithium abundance corrections.

Results. For all metallicities, the largest corrections are found at the coolest effective temperature, Teff = 5000 K. They are mostly positive, up to + 0.2 dex, for the weakest lines (lithium abundance A(Li)1DLTE = 1.0), whereas they become more negative towards lower metallicities, where they can reach − 0.4 dex for the strongest lines (A(Li)1DLTE = 3.0) at [Fe/H] = − 2.0. We demonstrate that 3D and NLTE effects are small for metal-poor stars on the Spite plateau, leading to errors of at most ± 0.05 dex if ignored. We present analytical functions evaluating the 3D NLTE and 1D NLTE corrections as a function of Teff [5000…6500 K], log g [3.5…4.5], and LTE lithium abundance A(Li) [1.0…3.0] for a fixed grid of metallicities [Fe∕H] [ − 3.0…0.0]. In addition, we also provide analytical fitting functions for directly converting a given lithium abundance into an equivalent width, or vice versa, a given equivalent width (EW) into a lithium abundance. For convenience, a Python script is made available that evaluates all fitting functions for given Teff, log g, [Fe∕H], and A(Li) or EW.

Conclusions. By means of the fitting functions developed in this work, the results of complex 3D and NLTE calculations are made readily accessible and quickly applicable to large samples of stars across a wide range of metallicities. Improving the accuracy of spectroscopic lithium abundance determinations will contribute to a better understanding of the open questions related to the lithium content in metal-poor and solar-like stellar atmospheres.
Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole
Authors:   GRAVITY Collaboration, Abuter R. , Amorim A. , Bauböck M. , Berger J. P. , Bonnet H. , Brandner W. , Cardoso V. , Clénet Y. , de Zeeuw P. T. , Dexter J. , Eckart A. , Eisenhauer F. , Förster Schreiber N. M. , Garcia P. , Gao F. , Gendron E. , Genzel R. , Gillessen S. , Habibi M. , Haubois X. , Henning T. , Hippler S. , Horrobin M. , Jiménez-Rosales A. , Jochum L. , Jocou L. , Kaufer A. , Kervella P. , Lacour S. , Lapeyrère V. , Le Bouquin J.-B. , Léna P. , Nowak M. , Ott T. , Paumard T. , Perraut K. , Perrin G. , Pfuhl O. , Rodríguez-Coira G. , Shangguan J. , Scheithauer S. , Stadler J. , Straub O. , Straubmeier C. , Sturm E. , Tacconi L. J. , Vincent F. , von Fellenberg S. , Waisberg I. , Widmann F. , Wieprecht E. , Wiezorrek E. , Woillez J. , Yazici S. , Zins G.
Published: April 2020

The star S2 orbiting the compact radio source Sgr A* is a precision probe of the gravitational field around the closest massive black hole (candidate). Over the last 2.7 decades we have monitored the star’s radial velocity and motion on the sky, mainly with the SINFONI and NACO adaptive optics (AO) instruments on the ESO VLT, and since 2017, with the four-telescope interferometric beam combiner instrument GRAVITY. In this Letter we report the first detection of the General Relativity (GR) Schwarzschild Precession (SP) in S2’s orbit. Owing to its highly elliptical orbit (e = 0.88), S2’s SP is mainly a kink between the pre-and post-pericentre directions of motion ≈±1 year around pericentre passage, relative to the corresponding Kepler orbit. The superb 2017−2019 astrometry of GRAVITY defines the pericentre passage and outgoing direction. The incoming direction is anchored by 118 NACO-AO measurements of S2’s position in the infrared reference frame, with an additional 75 direct measurements of the S2-Sgr A* separation during bright states (“flares”) of Sgr A*. Our 14-parameter model fits for the distance, central mass, the position and motion of the reference frame of the AO astrometry relative to the mass, the six parameters of the orbit, as well as a dimensionless parameter fSP for the SP (fSP = 0 for Newton and 1 for GR). From data up to the end of 2019 we robustly detect the SP of S2, δϕ ≈ 12′ per orbital period. From posterior fitting and MCMC Bayesian analysis with different weighting schemes and bootstrapping we find fSP = 1.10 ± 0.19. The S2 data are fully consistent with GR. Any extended mass inside S2’s orbit cannot exceed ≈0.1% of the central mass. Any compact third mass inside the central arcsecond must be less than about 1000 M⊙.
Planet formation by pebble accretion in ringed disks
Authors: Morbidelli A.
Published: April 2020

Context.Pebble accretion is expected to be the dominant process for the formation of massive solid planets, such as the cores of giant planets and super-Earths. So far, this process has been studied under the assumption that dust coagulates and drifts throughout the full protoplanetary disk. However, observations show that many disks are structured in rings that may be due to pressure maxima, preventing the global radial drift of the dust.

Aims.We aim to study how the pebble-accretion paradigm changes if the dust is confined in a ring.

Methods.Our approach is mostly analytic. We derived a formula that provides an upper bound to the growth of a planet as a function of time. We also numerically implemented the analytic formulæ to compute the growth of a planet located in a typical ring observed in the DSHARP survey, as well as in a putative ring rescaled at 5 AU.

Results.Planet Type I migration is stopped in a ring, but not necessarily at its center. If the entropy-driven corotation torque is desaturated, the planet is located in a region with low dust density, which severely limits its accretion rate. If the planet is instead near the ring’s center, its accretion rate can be similar to the one it would have in a classic (ringless) disk of equivalent dust density. However, the growth rate of the planet is limited by the diffusion of dust in the ring, and the final planet mass is bounded by the total ring mass. The DSHARP rings are too far from the star to allow the formation of massive planets within the disk’s lifetime. However, a similar ring rescaled to 5 AU could lead to the formation of a planet incorporating the full ring mass in less than 1/2 My.

Conclusions.The existence of rings may not be an obstacle to planet formation by pebble-accretion. However, for accretion to be effective, the resting position of the planet has to be relatively near the ring’s center, and the ring needs to be not too far from the central star. The formation of planets in rings can explain the existence of giant planets with core masses smaller than the so-called pebble isolation mass.
Streamflow prediction in ungauged basins: benchmarking the efficiency of deep learning
Authors: Ayzel Georgy , Kurochkina Liubov , Kazakov Eduard , Zhuravlev Sergei
Published: April 2020

Streamflow prediction is a vital public service that helps to establish flash-flood early warning systems or assess the impact of projected climate change on water management. However, the availability of streamflow observations limits the utilization of the state-of-the-art streamflow prediction techniques to the basins where hydrometric gauging stations exist. Since the most river basins in the world are ungauged, the development of the specialized techniques for the reliable streamflow prediction in ungauged basins (PUB) is of crucial importance. In recent years, the emerging field of deep learning provides a myriad of new models that can breathe new life into the stagnating PUB methods. In the presented study, we benchmark the streamflow prediction efficiency of Long Short-Term Memory (LSTM) networks against the standard technique of GR4J hydrological model parameters regionalization (HMREG) at 200 basins in Northwest Russia. Results show that the LSTM-based regional hydrological model significantly outperforms the HMREG scheme in terms of median Nash-Sutcliffe efficiency (NSE), which is 0.73 and 0.61 for LSTM and HMREG, respectively. Moreover, LSTM demonstrates the comparable median NSE with that for basin-scale calibration of GR4J (0.75). Therefore, this study underlines the high utilization potential of deep learning for the PUB by demonstrating the new state-of-the-art performance in this field.
Modeling of runoff formation processes in mountain conditions of the Crimean Peninsula (Russia)
Authors: Zemlyanskova Anastasiia , Makarieva Olga , Nesterova Nataliia , Fedorova Alexandra
Published: April 2020

The distributed hydrological model Hydrograph was applied to simulate runoff formation processes in the mountainous conditions of the Crimean Peninsula. The study object is the Derekoyka River watershed (49.7 km2, the altitude difference 14-1398 m). Streamflow simulations were carried out with daily time step for the periods of 1967-1988 and 2016-2017 using the data of two weather stations Ai-Petri and Yalta. Though mean and median Nash-Sutcliffe efficiency was only 0.28 and 0.33, in some years it exceeded 0.60. The analysis has shown that the precipitation input interpolated from weather stations was not always adequate affecting the quality of streamflow simulations. The results of the model verification were accepted as satisfactory. The hazardous flood of 2018 in Yalta was simulated. According to simulations, maximum daily discharge amounted to 14.9 m3/s and exceeded previous maximum value observed in 1962. The results confirm the possibility to apply the model Hydrograph to assess the water balance and hydrological characteristics in the mountainous part of the Crimean Peninsula. We suggest that provided by proper precipitation data the model can be used for short-term forecasts of hazardous floods in the region.
Automated short-term forecast system based on open-source hydrological models for the Tikhvinka river (Leningrad region of Russia)
Authors: Kazakov Eduard , Shemanaev Kirill , Zhuravlev Sergey , Sarafanov Mikhail , Borisova Yulia , Kurochkina Lyubov
Published: April 2020

In recent decades there has been a trend towards an increase in the number of dangerous hydrological events, especially floods. In order to protect citizens and solve economic problems, it is important to develop and actively introduce into operational practice methods of hydrological forecasting, as well as to build more modern and convenient interfaces of interaction between hydrometeorological services, municipal authorities and citizens. This work discusses a compact automated short-term hydrological forecasting system that uses open-source conceptual models HBV, SimHYD and GR4J as its core. The system is connected to data streams on the observed temperatures and precipitation in the watershed basin, as well as the predicted values of these parameters (in a current implementation, the WRF model with a forecast for 84 hours is used). Also, for operational calibration in daily mode, the system can assimilate (if available) data on observed water levels. Testing of the system is carried out on the example of Tikhvin city (the Tikhvinka river), which in recent years has been characterized by frequent flooding.
Around Baikal: on the causes of ecological problems
Authors: Korytny Leonid , Gagarinova Olga
Published: April 2020

This paper is devoted to the unique water body, Lake Baikal, the largest freshwater reservoir by volume in the world that was included on the list of UNESCO World Heritage Sites and is regulated by the federal law of its protection. The global role of Baikal as a strategic reserve of water resources of the highest class is increasing in importance. Furthermore, Lake Baikal and its surroundings are invariably the focus of ecological problems. The most challenging issues are the lake’s water pollution leading to changes in hydrobiocenoses, soil and vegetation digression in areas of increased recreational load, forest fires causing a decrease of the number of rare species of flora and fauna, etc. Imperfection of the legal framework, the lack of a unified managerial center and the attempts to deal with the problems solely at the federal level involve a number of incompetent decisions on the lake level regulation and on the setting of its water-protection zone. The conflicts of the interests of the subjects of the federal and regional levels in issues related to use and the protection of natural resources present serious obstacles to the development of a unified, ecologically oriented strategy of economic development of the territory. For a successful solution of the current challenges it is necessary to recognize the ecological problems of Lake Baikal as the priority concerns throughout the country, optimize management of the socio-economic development of the Baikal natural territory on the basis of nature-conservation principles by ensuring appropriate funding, develop a unified scheme of comprehensive monitoring of the ecological and sanitary-hygienic status of Lake Baikal and its protection zone, improve the system of scientific research on the Baikal natural territory, introduction ubiquitous ecological training and education of the population, organize the waste and effluent treatment system in accordance with the latest international technologies, etc.
Reasons and patterns of spatio-temporal variability of methane emission from the Mozhaysk reservoir in summer period
Authors: Lomov Viktor , Grechushnikova Maria , Kazantsev Vladimir , Repina Irina
Published: April 2020

Anthropogenic reservoirs are not only sources of clean energy, flow regulators, recreational and food resources, but also sources of greenhouse gases such as methane. The studies presented in this work, done on a well-studied low-flowing valley reservoir mainly in the summer, when the greatest variability of methane fluxes was observe. Depending on synoptic conditions, the temporal variability of methane fluxes varies greatly. Methane fluxes increase during the summer period and huge methane emissions observed before the autumn mixing stage. Emissions can occur during the destruction of temperature stratification, as a result of stormy weather. With such emissions, methane fluxes into the atmosphere can reach about 20 mgC*m-2*d-1, which is higher than the emission during convection. Revealing the patterns of spatio-temporal distribution of methane fluxes will help to determine the contribution of water bodies (in particular reservoirs) to the total methane budget of the atmosphere more accurately.
Actual issues of assessment and regulation of surface water quality
Authors: Venitsianov Eugeny , Adzhienko Georgy , Yasinsky Sergey , Kozlova Mariya
Published: April 2020

The current state of surface water quality is stable, but it is characterized by a number of problems that collectively call into question the effectiveness of the current water management system in the country. Over a long period of time, the volume of pollutants entering the uncontrolled, mainly diffuse, runoff to water bodies determines the unsatisfactory quality of natural waters and the poor environmental condition of water bodies. This is a consequence of the imperfection of the current water management system.
Deposition of Lu-Fe-O thin films on silica glass substrates by MOCVD
Authors: Cardoso A.F. , Bassou A.A. , Amaral V.S. , Fernandes J.R. , Tavares P.B.
Published: April 2020

Thin films of the Lu-Fe-O system were deposited by aerosol assisted MOCVD on silica glass substrates. Hexagonal h-LuFeO3, garnet Lu3Fe5O12, perovskite o-LuFeO3 or hematite Fe2O3 phases were obtained, depending on the thermodynamic deposition conditions or post annealing temperature. Magnetic measurements confirm the ferromagnetic behaviour at room temperature of the thin films with garnet phase. An indirect bandgap of 1.78 eV was measured.
Numerical Simulation of Non-Equilibrium Stationary Currents Through Nano-scale One-Dimensional Chains
Authors: dos Santos Pires João Pedro , Amorim Bruno , Viana Parente Lopes João Manuel
Published: April 2020

Using a method based on the time-evolution of the occupied states at zero temperature, we observe the onset of a quasi-uniform and quasisteady state current across a disordered tight-binding chain, coupled between two finite (but large) clean leads with open boundaries. This current is seen to match the one obtained in the Landauer-Büttiker formalism and is also independent of the initial condition considered (partitioned or non-partitioned). Finite-size effects are also reported and briefly discussed.