bluuebunny/crossref_metadata_2025 huggingface dataset:
Topology planning for autonomous MMGs: an ordered binary decision diagram‐based approach
Authors: Khan Hafiz Anwar Ullah , Al Hosani Mohamed , Zeineldin Hatem
Published: October 2019

This paper finds its motivation from the perspective of utility planners, where the flexibility of choice while reconfiguring a distribution system into Multi‐Micrgrids (MMGs) is critical. To address the topology planning problem for MMGs from this dimension, a holistic algorithm incorporating graph theory, ordered binary decision diagrams, and a modified Gauss Siedel power flow algorithm is proposed. This multi‐indexed, multi‐tier scheme guarantees self‐adequacy and reliability of individual microgrids (MGs) by effectively solving a modified balanced partitioning problem, and ensures validation of inequality constraints through power flow studies. The available solutions are ranked according to two system‐level performance indices to provide a hierarchically feasible solution list to system planner. This algorithm is presented as an alternate tool for heuristic techniques to ensure a complete search of solution space and to increase the number of available topology planning solutions for the system operator. The flexibility of choice offered by this planning algorithm, tendency to be employed as a resource assessment tool, and incorporation of power flow analysis for autonomous MGs renders it to be practically superior to its counterparts. The proposed algorithm is tested to furnish its advantages and applicability in practical utility systems.
Ensembled machine learning framework for drug sensitivity prediction
Authors: Sharma Aman , Rani Rinkle
Published: October 2019

Drug sensitivity prediction is one of the critical tasks involved in drug designing and discovery. Recently several online databases and consortiums have contributed to providing open access to pharmacogenomic data. These databases have helped in developing computational approaches for drug sensitivity prediction. Cancer is a complex disease involving the heterogeneous behaviour of same tumour‐type patients towards the same kind of drug therapy. Several methods have been proposed in the literature to predict drug sensitivity. However, these methods are not efficient enough to predict drug sensitivity. The present study has proposed an ensemble learning framework for drug‐response prediction using a modified rotation forest. The proposed framework is further compared with three state‐of‐the‐art algorithms and two baseline methods using Genomics of Drug Sensitivity in Cancer (GDSC) and Cancer Cell Line Encyclopedia (CCLE) drug screens. The authors have also predicted missing drug response values in the data set using the proposed approach. The proposed approach outperforms other counterparts even though gene mutation data is not incorporated while designing the approach. An average mean square error of 3.14 and 0.404 is achieved using GDSC and CCLE drug screens, respectively. The obtained results show that the proposed framework has considerable potential to improve anti‐cancer drug response prediction.
Attractive passive direct positioning algorithm for localisation of multiple transmitters based on eigenvalue maximizing
Authors: Chen Fangxiang , Zhou Tao , Sun Bin , Kong Lingjiang
Published: October 2019

In terms of the passive position determination problem, the most commonly used methods are based on two‐step processing. While here, the authors propose a technique that estimates the locations of transmitters by processing the raw signals from all receivers at the central processor, which belongs to the direct position determination (DPD) concept. There are already efforts made on single target localisation through eigenvalue maximising based on the DPD technique. While the multi‐target case encountered more commonly in realistic scenarios. By additionally combined with the image expansion algorithm, the sources can be extracted effectively and their positions are determined simultaneously. Simulation results illustrate that the localisation accuracy for each transmitter is equivalent to the two‐step based approach at high signal‐to‐noise ratio (SNR). While for low SNR, the superiority and accuracy of the proposed method are also manifested.
Preparation and characteristics of tunnelling effect transistor using copper phthalocyanine
Authors: Zhang Zhiwen , Wang Dongxing , Yang Meizhong , Yuan Danni
Published: October 2019

A tunnelling effect transistor based on copper phthalocyanine (CuPc) has been fabricated. CuPc is the active layer of transistors. The basic characteristics of the transistor are measured. The device shows unsaturated output characteristics. The output current can be modulated by demanding different gate voltage. At VDS = 3 V and VGS = 0 V, the drain‐source current is 1.89 × 10−4 A. The current density is 4.73 × 10−3 A/cm2. The tunnel injection model is used to analyse the carrier transport inside the transistor. The microscopic operating mechanism of the device is investigated. The results show that the operating current of the transistor conforms to the tunnelling effect theory.
Nonlinear coupled axial–torsional vibration of single‐walled carbon nanotubes using homotopy perturbation method
Authors: Fatahi‐Vajari Alireza , Azimzadeh Zahra , Hussain Muzamal
Published: October 2019

This work analyses the nonlinear coupled axial–torsional vibration of single‐walled carbon nanotubes (SWCNTs) based on numerical methods. Two‐second order partial differential equations that govern the nonlinear coupled axial–torsional vibration for such nanotube are derived. First, these equations are reduced to ordinary differential equations using the Galerkin method and then solved using homotopy perturbation method (HPM) to obtain the nonlinear natural frequencies in coupled axial–torsional vibration mode. It is found that the obtained frequencies are complicated due to coupling between two vibration modes. The dependence of boundary conditions, vibration modes and nanotubes geometry on the nonlinear coupled axial–torsional vibration characteristics of SWCNTs are studied in detail. It was shown that boundary conditions and maximum initial vibration velocity have significant effects on the nonlinear coupled axial–torsional vibration response of SWCNTs. It was also seen that unlike the linear model if the maximum vibration velocity increases, the natural frequencies of vibration increases too. To show the effectiveness and ability of this method, the results obtained with HPM are compared with the fourth‐order Runge‐Kutta numerical results and good agreement is observed. To the knowledge of authors, the results given herein are new and can be used as a foundation work for future work.
Structural and optical properties of Ce doped BiFeO3 nanoparticles via sol–gel method
Authors: Li Jin , Guan Xiao Ying
Published: October 2019

The effect of Ce doping on the structural and optical properties of BiFeO3 nanoparticles via sol–gel method is reported. All samples were a pure phase with perovskite structure. The EDX results show the doped samples contain Bi, Fe, O and Ce elements. The vibrational properties of samples were studied using Raman spectroscopy. Photoluminescence shows an intense peak at 398 nm, the peak strength enhanced greatly and had redshift with the increase of Ce doping concentration. UV–vis results show the samples have a broad absorption band in the range of 500–600 nm. The bandgaps decrease with the concentration increase of Ce doping. It indicates the as‐prepared BiFeO3 can be used as visible light catalyst.
Low‐cost pyrophyllite‐based microfluidic device for the study of enhanced oil recovery
Authors: Gao Kexin , Cui Rubing , Fan Yiqiang , Zhou Xuance , Zhang Yajun
Published: October 2019

This work proposed a novel method for the fabrication of pyrophyllite‐based microfluidic devices for enhanced oil recovery (EOR). Pyrophyllite has good heat resistance, corrosion resistance and similar molecular structure to quartz sandstone, and is suitable for EOR research. A rectangular matrix of the pore structure is designed, representing an idealised porous medium and then fabricated on the surface of pyrophyllite substrate by using the micro‐milling method. Finally, a layer of sealing film was applied on the surface of substrate to finish the bonding process. A droplet generator was also fabricated for the demonstration of the proposed technology. A series of displacement experiments with water flooding and surfactant flooding were conducted and the result was carefully analysed and discussed. Compared with the previous study using polymer‐based or glass‐based microfluidic devices as micromodels for the displacement study in oil recovery process, the surface properties of pyrophyllite are more close to real reservoirs and have compelling advantages as bulk material for microfluidic devices for the EOR study. This work has wide potential applications as the micromodels in EOR research, the proposed fabrication protocols of the pyrophyllite‐based microfluidic device are rapid and low‐cost, the on‐site field test could also be conducted with the proposed technology.
Measuring relative abundances in the solar corona with optimised linear combinations of spectral lines
Authors: Zambrana Prado Natalia , Buchlin Éric
Published: October 2019

Context. Elemental abundances in some coronal structures differ significantly from photospheric abundances, with a dependence on the first ionization potential (FIP) of the element. Measuring these FIP-dependent abundance biases is important for coronal and heliospheric physics.

Aims. We aim to build a method for optimal determination of FIP biases in the corona from spectroscopic observations in a way that is in practice independent from differential emission measure (DEM) inversions.

Methods. We optimised linear combinations of spectroscopic lines of low-FIP and high-FIP elements so that the ratio of the corresponding radiances yields the relative FIP bias with good accuracy for any DEM in a small set of typical DEMs.

Results. These optimised linear combinations of lines allow retrieval of a test FIP bias map with good accuracy for all DEMs in the map. The results also compare well with a FIP bias map obtained from observations using a DEM-dependent method.

Conclusions. The method provides a convenient, fast, and accurate way of computing relative FIP bias maps. It can be used to optimise the use of existing observations and the design of new observations and instruments.
The Galactic Faraday depth sky revisited
Authors: Hutschenreuter Sebastian , Enßlin Torsten A.
Published: October 2019

Context. The Galactic Faraday depth sky is a tracer for both the Galactic magnetic field and the thermal electron distribution. It was previously reconstructed from polarimetric measurements of extra-Galactic point sources.

Aims. Here we improve on these works by using an updated inference algorithm and by taking into account the electron emission measure as traced by free–free emission measured by the Planck survey. In the future the data situation will improve drastically thanks to the next generation Faraday rotation measurements from the SKA and its pathfinders. Anticipating this, a further aim of this paper is to update the map reconstruction method with some of the latest developments in Bayesian imaging.

Methods. To this end we made use of information field theory, an inference scheme that is particularly powerful in cases of noisy and incomplete data.

Results. We demonstrate the validity of the new algorithm by applying it to an existing data compilation. Even though we used exactly the same data set, a number of novel findings are made; for example, a non-parametric reconstruction of an overall amplitude field resembles the free–free emission measure map of the Galaxy. Folding this emission measure map into the analysis provides more detailed predictions. The joint inference enables us to identify regions with deviations from the assumed correlations between the emission measure and Faraday data, thereby pointing us to Galactic structures with distinguishably different physics. We find evidence for an alignment of the magnetic field within the lines of sight along both directions of the Orion arm.
Modeling non-thermal emission from the jet-launching region of M 87 with adaptive mesh refinement
Authors: Davelaar Jordy , Olivares Hector , Porth Oliver , Bronzwaer Thomas , Janssen Michael , Roelofs Freek , Mizuno Yosuke , Fromm Christian M. , Falcke Heino , Rezzolla Luciano
Published: October 2019

Context. The galaxy M 87 harbors a kiloparsec-scale relativistic jet, whose origin coincides with a compact source thought to be a supermassive black hole. Observational millimeter very long baseline interferometry campaigns are capable of resolving the jet-launching region at the scale of the event horizon. In order to provide a context for interpreting these observations, realistic general-relativistic magnetohydrodynamical (GRMHD) models of the accretion flow are constructed.

Aims. Electrons in the jet are responsible for the observed synchrotron radiation, which is emitted in frequencies ranging from radio to near-infrared (NIR) and optical. The characteristics of the emitted radiation depend on the shape of the electrons’ energy-distribution function (eDF). The dependency on the eDF is omitted in the modeling of the first Event Horizon Telescope results. In this work, we aim to model the M 87 spectral-energy distribution from radio up to optical frequencies using a thermal-relativistic Maxwell–Jüttner distribution, as well as a relativistic κ-distribution function. The power-law index of the eDF is modeled based on sub-grid, particle-in-cell parametrizations for sub-relativistic reconnection.

Methods. A GRMHD simulation in Cartesian–Kerr–Schild coordinates, using eight levels of adaptive mesh refinement (AMR), forms the basis of our model. To obtain spectra and images, the GRMHD data was post-processed with the ray-tracing code RAPTOR, which is capable of ray tracing through GRMHD simulation data that is stored in multi-level AMR grids. The resulting spectra and images maps are compared with observations.

Results. We obtain radio spectra in both the thermal-jet and κ-jet models consistent with radio observations. Additionally, the κ-jet models also recover the NIR and optical emission. The images show a more extended structure at 43 GHz and 86 GHz and more compact emission at 228 GHz. The models recover the observed source sizes and core shifts and obtain a jet power of ≈1043 ergs s−1. In the κ-jet models, both the accretion rates and jet powers are approximately two times lower than the thermal-jet model. The frequency cut-off observed at ν ≈ 1015 Hz is recovered when the accelerator size is 106 − 108 cm, this could potentially point to an upper limit for plasmoid sizes in the jet of M 87.
Bar pattern speeds in CALIFA galaxies
Authors: Cuomo Virginia , Lopez Aguerri J. Alfonso , Corsini Enrico Maria , Debattista Victor P. , Méndez-Abreu Jairo , Pizzella Alessandro
Published: October 2019

Context.About 35% of the nearby disc galaxies host a weak bar for which different formation scenarios, including the weakening of a strong bar and tidal interaction with a companion, have been suggested. Measuring the bar pattern speeds of a sample of weakly barred galaxies is a key step in constraining their formation process, but such a systematic investigation is still missing.

Aims.We investigated the formation process of weak bars by measuring their properties in a sample of 29 nearby weakly barred galaxies, spanning a wide range of morphological types and luminosities. The sample galaxies were selected to have an intermediate inclination, a bar at an intermediate angle between the disc minor and major axes, and an undisturbed morphology and kinematics to allow the direct measurement of the bar pattern speed. Combining our analysis with previous studies, we compared the properties of weak and strong bars.

Methods.We measured the bar radius and strength from therband images available in the Sloan Digital Sky Survey and bar pattern speed and corotation radius from the stellar kinematics obtained by the Calar Alto Legacy Integral Field Area Survey. We derived the bar rotation rate as the ratio between the corotation and bar radii.

Results.Thirteen out of 29 galaxies (45%), which were morphologically classified as weakly barred from a visual inspection, do not actually host a bar component or their central elongated component is not in rigid rotation. We successfully derived the bar pattern speed in 16 objects. Two of them host an ultrafast bar. Using the bar strength to differentiate between weak and strong bars, we found that the weakly barred galaxies host shorter bars with smaller corotation radii than their strongly barred counterparts. Weak and strong bars have similar bar pattern speeds and rotation rates, which are all consistent with being fast. We did not observe any difference between the bulge prominence in weakly and strongly barred galaxies, whereas nearly all the weak bars reside in the disc inner parts, contrary to strong bars.

Conclusions.We ruled out that the bar weakening is only related to the bulge prominence and that the formation of weak bars is triggered by the tidal interaction with a companion. Our observational results suggest that weak bars may be evolved systems exchanging less angular momentum with other galactic components than strong bars.
Towards a 1% measurement of the Hubble constant: accounting for time dilation in variable-star light curves
Authors: Anderson Richard I.
Published: October 2019

Assessing the significance and implications of the recently established Hubble tension requires the comprehensive identification, quantification, and mitigation of uncertainties and/or biases affecting H0 measurements. Here, we investigate the previously overlooked distance scale bias resulting from the interplay between redshift and Leavitt laws in an expanding Universe: Redshift-Leavitt bias (RLB). Redshift dilates oscillation periods of pulsating stars residing in supernova-host galaxies relative to periods of identical stars residing in nearby (anchor) galaxies. Multiplying dilated log P with Leavitt Law slopes leads to underestimated absolute magnitudes, overestimated distance moduli, and a systematic error on H0. Emulating the SH0ES distance ladder, we estimate an associated H0 bias of (0.27 ± 0.01)% and obtain a corrected H0 = 73.70 ± 1.40 km s−1 Mpc−1. RLB becomes increasingly relevant as distance ladder calibrations pursue greater numbers of ever more distant galaxies hosting both Cepheids (or Miras) and type-Ia supernovae. The measured periods of oscillating stars can readily be corrected for heliocentric redshift (e.g. of their host galaxies) in order to ensure H0 measurements free of RLB.
Antikoagulation und Thrombozytenaggregationshemmung bei chronischer Nierenkrankheit
Authors: Schirmer Stephan H. , Brandenburg Vincent , Antlanger Marlies
Published: October 2019

Was ist neu?

Orale Antikoagulation bei nicht dialysepflichtiger chronischer Nierenkrankheit In großen Zulassungsstudien haben sich die Nicht-Vitamin-K-abhängigen oralen Antikoagulanzien (NOAK) bei Patienten mit nicht valvulärem Vorhofflimmern als mindestens so effektiv in der Verhinderung thromboembolischer Ereignisse gezeigt wie Vitamin-K-Antagonisten (VKA). Die NOAK zeigen generell eine geringere Neigung zu schweren, lebensbedrohlichen Blutungen als die VKA. In den Zulassungsstudien wurden Patienten mit einer Kreatinin-Clearance von kleiner 30 ml/min meist nicht inkludiert, sodass für Patienten mit einer Kreatinin-Clearance von 15–30 ml/min zwar für Rivaroxaban, Apixaban und Edoxaban eine Zulassung besteht, die Datenlage zur Effektivität und Sicherheit jedoch nicht so fundiert ist wie bei Patienten mit einer Kreatinin-Clearance von > 30 ml/min.

Antikoagulation bei terminaler Niereninsuffizienz Die Indikation zur Antikoagulation muss bei chronischen Dialysepatienten mit Vorhofflimmern derzeit weiterhin individualisiert gestellt werden. Es ist in diesem Kollektiv unklar, ob dialysepflichtige VHF-Patienten überhaupt von einer oralen Antikoagulation profitieren und welches hierfür eine sichere und effektive Substanz ist: Randomisiert-kontrollierte Studien zu Apixaban versus VKA werden klären, ob NOAK eine sichere und effiziente Therapiestrategie bei diesem Patientenkollektiv sind (RENAL-AF, AXADIA).

Thrombozytenaggregationshemmung bei chronischer Nierenkrankheit Generell sollten Patienten auch mit schwerer CKD oder Dialysepflichtigkeit die Thrombozytenaggregationshemmung nach kardiologischer Leitlinienempfehlung erhalten. Auf dem Boden des erhöhten Blutungsrisikos in diesem Kollektiv erscheinen moderne Kombinationen aus NOAK und einer einzelnen TAH-Substanz, die das alte „Triple-Regime“, bestehend aus doppelter TAH plus VKA ersetzen, besonders interessant.
Infektionen des Auges – was sollten Internisten wissen?
Authors: Neß Thomas , Reinhard Thomas
Published: October 2019

Was ist neu?

Hornhautentzündung (Keratitis) Eine Keratitis kann durch viele unterschiedliche Erreger verursacht werden.

Infektiöse Uveitis Bei der infektiösen Uveitis zeigen sich vermehrt alte Infektionen wie die Syphilis oder die Tuberkulose, aber auch lokale Infektionen mit Protozoen oder Viren.

Endophthalmitis Die Endophthalmitis als Komplikation von intraokularen Eingriffen gewinnt durch die Zunahme der Kataraktoperationen und vor allem der intravitrealen Medikamentengabe immer mehr an Bedeutung.
The effect of gender-specific invitation letters on utilization of colorectal cancer screening
Authors: Zhan Tianzuo , Hielscher Thomas , Eckardt Maximilian , Giese Thomas , Schäfer Christoph , Riemann Jürgen F. , Ebert Matthias P. , Belle Sebastian
Published: October 2019

Background and aim Colorectal cancer (CRC) screening can effectively reduce cancer-associated mortality. In Germany, individuals over the age of 50 or 55 have access to CRC screening services. However, utilization rates are persistently low, particular in the male population. This observational study investigates the effect of standard versus gender-specific invitation letters on utilization of CRC screening services.

Methods We analyzed utilization rates of individuals who were insured by a large health insurance fund in Bavaria, Germany. Persons who became eligible for CRC screening received a standard (2013–2014) or a gender-specific invitation letter (2015–2016). We compared utilization rates within 6 months after receipt of the invitation letter using billing codes of the health insurance fund.

Results Invitation letters were sent to 49 535 individuals, of which 48.8 % were gender-specific. The overall utilization rate did not differ between recipients of the standard versus gender-specific invitation letter (11.6 % vs 11.1 %; RR: 0.97 [0.92–1.02], p = 0.19). However, uptake of screening colonoscopy was significantly higher among recipients of gender-specific invitations (2.9 % vs 3.5 %; RR: 1.21 [1.04–1.39], p = 0.01), whereas utilization of fecal occult blood tests declined (10.4 % vs 9.7 %; RR: 0.93 [0.88–0.99], p = 0.016).

Conclusions Gender-specific design of invitation letters can modify the patients’ preference for specific CRC screening services and increase the acceptance of screening colonoscopy.
Synthesis of 5-Substituted 2-Pyrrolidinones by Coupling of Organozinc Reagents with Cyclic N-Acyliminium Ions
Authors: Zaragoza-Galicia Ivann , Santos-Sánchez Zaira A. , Hidalgo-Mercado Yazmín I. , Olivo Horacio F. , Romero-Ortega Moisés
Published: October 2019

A coupling reaction between cyclic N-acyliminium ions with organozinc reagents is described. The cyclic N-acyliminium ions, generated in situ from N-substituted-5-hydroxy-2-pyrrolidinones by treatment with boron trifluoride–diethyl ether complex or titanium tetrachloride, are trapped by the organozinc reagent, which is formed from an alkyl bromide in the presence of zinc in the same reaction medium. The N-substituted-5-allyl-2-pyrrolidinones generated using this method serve as versatile intermediates for the synthesis of azabicyclic systems with indolizidine and pyrroloazepinolizidine cores.
A Photoredox Catalysis Approach for the Synthesis of Both the ABDE and the ABCD Cores of Tronocarpine
Authors: Contreras-Cruz David A. , Castañón-García Mario , Becerril-Rodríguez Enrique , Miranda Luis D.
Published: October 2019

A general strategy for the facile construction of both the ABDE and ABCD cores of tronocarpine, chippiine and dippinine alkaloids through the retrosynthetic disconnection of the polycyclic motifs into an indole or tryptamine fragment and a suitably functionalized alkyl chain is presented. The approach is enabled by an efficient Ir(III)-catalyzed, photoredox-mediated radical addition of tetramethyl 1-bromopentane-1,1,3,5-tetracarboxylate and dimethyl 2-bromopentanedioate selectively at C-2 of the indole. Subsequent intramolecular cyclization events furnish the desired ABDE and ABCD polycyclic cores in good preparative yields.
Recent Advances in Reactions of Propargylamines
Authors: Sheng Xia , Chen Kaijun , Shi Chengjin , Huang Dayun
Published: October 2019

Propargylamines are extremely versatile and common building blocks in the field of chemistry. This review highlights the recent advances made in the reactions of propargylamines between 2009 and 2019. The reaction types are classified into six categories based on the trigger mechanisms: (1) amino moieties as leaving groups, (2) hydrogenation, (3) rearrangement, (4) nucleophilic amines, (5) nucleophilic carbons, and (6) electrophilic alkynes. We hope that this review will promote future research in this area.

1 Introduction

2 Amino Moieties as Leaving Groups

3 Hydrogenation

4 Rearrangement

5 Nucleophilic Amines

6 Nucleophilic Carbons

7 Electrophilic Alkynes

8 Conclusions
Simple Apparatus for Adding Small Amounts of Powder Materials under an Inert Atmosphere
Authors: Karak Milandip , Joh Yohei , Khodjaniyazov Khamid U. , Sagdullaev Shamansur S. , Oishi Tohru , Torikai Kohei
Published: October 2019

Addition of reactants under an inert atmosphere is a fundamental but extremely important technique in synthetic chemistry. Although this is achievable in many cases by using a glove box or a Schlenk-and-syringe technique, the direct addition of powder (solid) materials without contamination by air or moisture has been difficult, especially in the later stages of a reaction. Here, we offer a simple and small apparatus to realize powder addition with easy handling. Use of this apparatus permitted one-pot glycosylation reactions that required extremely dry conditions to be performed in a highly reproducible manner.
Carrier and heat transport properties of poly-crystalline GeSn films for thin-film transistor applications
Authors: Uchida Noriyuki , Hattori Junichi , Lieten Ruben R. , Ohishi Yuji , Takase Ryohei , Ishimaru Manabu , Fukuda Koichi , Maeda Tatsuro , Locquet Jean-Pierre
Published: October 2019

Thin-film transistors (TFTs) on insulator substrates are widely used in applications from liquid crystal displays to sensor devices. However, insulator substrates with low heat conductivity lead to unfavorable self-heating effects in the channel regions. Herein, the carrier and heat transport properties of polycrystalline GeSn films on SiO2/Si substrates were improved by suppressing Sn segregation in the films to fabricate GeSn channel TFTs. Alloying with 5.5% Sn enabled the formation of larger grains than those in poly-Ge films after low-temperature annealing (below 520 °C) without Sn segregation. In addition, the films had a hole mobility of 40 cm2 V−1 s−1 at a hole density of 1.1 × 1018 cm−3 and a thermal conductivity of 12.1 Wm−1 K−1 at room temperature. The temperature dependences of the carrier and heat transport properties of the poly-GeSn films were investigated to accurately simulate a device with a poly-GeSn channel TFT. This was achieved by using the carrier transport measurements and numerical simulations of the heat transport in the Debye model. The simulated device allowed an accurate assessment of the self-heating effects of the TFT and thus provides a design guide for TFTs.
Optimizing spreading dynamics in interconnected networks
Authors: Pan Liming , Wang Wei , Cai Shimin , Zhou Tao
Published: October 2019

Adding edges between layers of interconnected networks is an important way to optimize the spreading dynamics. While previous studies mostly focused on the case of adding a single edge, the theoretical optimal strategy for adding multiple edges still need to be studied. In this study, based on the susceptible-infected-susceptible model, we investigate the problem of maximizing the stationary spreading prevalence in interconnected networks. For two isolated networks, we maximize the spreading prevalence near the critical point by choosing multiple interconnecting edges. We present a theoretical analysis based on the discrete-time Markov chain approach to derive the approximate optimal strategy. The optimal interlayer structure predicted by the strategy maximizes the spreading prevalence, meanwhile minimizing the spreading outbreak threshold for the interconnected network simultaneously. Numerical simulations on synthetic and real-world networks show that near the critical point, the proposed strategy gives better performance than connecting large degree nodes and randomly connecting.
The impulse pattern formulation (IPF) as a model of musical instruments—Investigation of stability and limits
Authors: Linke Simon , Bader Rolf , Mores Robert
Published: October 2019

The Impulse Pattern Formulation (IPF) is an analytical modeling approach for synergetic systems in general, motivated by research on musical instruments. Based on the assumption that the coupling of system components can be described by the interaction between individually propagating and exponentially damped impulse trains, the IPF describes tone generation in musical instruments as self-organized systems. In contrast to other nonlinear recursive functions such as the Logistic Map, system predictions cannot be derived easily from knowledge on other theories, neither can the system be completely examined analytically. Therefore, several numerical simulations are performed to explore stable regions and limits of the IPF.
Hydrogenation dynamics of Ru capped Y thin films
Authors: Soroka O. , Sturm J. M. , van de Kruijs R. W. E. , Makhotkin I. A. , Nikolaev K. , Yakunin S. N. , Lee C. J. , Bijkerk F.
Published: October 2019

The structural changes in Ru-coated Y films during hydrogenation were studied in this work. In situ XRD data were used to show that the Y to YH2 transition requires significant hydrogen loading of the Y lattice. By comparing the XRD data with the in situ spectroscopic ellipsometry data, an effective medium model for the transition was obtained. This model describes the Y to YH2 transition well. The YH2 to YH3 transition is also described by an effective medium model, however, with reduced accuracy around the midpoint of the transition. By comparing the YH2 and YH3 crystal sizes, we show that these deviations may be due to a surface plasmon resonance. The improved understanding of the ellipsometry measurements is important for optical hydrogen sensing applications.
Topological valley vortex manipulation of microparticles in phononic crystals
Authors: Dai Hongqing , Chen Tinggui , Jiao Junrui , Xia Baizhan , Yu Dejie
Published: October 2019

Topological valley states, emerging as an exciting field in condensed matter physics, are attracting attention because of their potential as a new type of information carrier with orbital angular momentum. In this paper, we exhibit that the acoustic valley states can achieve trapping of microparticles due to the acoustic radiation force induced by the acoustic vortex. In addition, we can achieve the separation of microparticles based on different acoustic contrast factors. Our study shows a demonstration of acoustic valley states in the field of particle contactless manipulation. Potential applications can be predicted by the exotic interaction of acoustic vortices with microparticles, such as cell separation, drug delivery, and other biomedical applications.
Application of two-branch deep neural network to predict bubble migration near elastic boundaries
Authors: Ma Xiaojian , Wang Chen , Huang Biao , Wang Guoyu
Published: October 2019

Compared to the drawbacks of traditional experimental and numerical methods for predicting bubble migration, such as high experimental costs and complex simulation operations, the data-driven approach of using deep neural network algorithms can provide an alternative method. The objective of this paper is to construct a two-branch deep neural network (TBDNN) model in order to improve the high-fidelity bubble migration results and further reduce dependence on the quantity of experimental data. A TBDNN model is obtained by embedding the features of the Kelvin impulse into a basic deep neural network (BDNN) system. The results show that compared to the original BDNN model, TBDNN performs much better in accurately predicting bubble migration based on the same amount of training data. Using the TBDNN model, the critical condition of bubble oscillation at a fixed location can be detected under the influence of boundary properties (normalized stiffness and mass) and bubble standoff. Furthermore, the initial position of the bubble and normalized stiffness of boundaries have a positive correlation with bubble migration, whereas normalized mass has a negative impact. It was found that the normalized mass of boundaries plays the most important role in affecting bubble migration compared to the standoff and stiffness when using the method of variable sensitivity analysis.
Learning from the density to correct total energy and forces in first principle simulations
Authors: Dick Sebastian , Fernandez-Serra Marivi
Published: October 2019

We propose a new molecular simulation framework that combines the transferability, robustness, and chemical flexibility of an ab initio method with the accuracy and efficiency of a machine learning model. The key to achieve this mix is to use a standard density functional theory (DFT) simulation as a preprocessor for the atomic and molecular information, obtaining a good quality electronic density. General, symmetry preserving, atom-centered electronic descriptors are then built from this density to train a neural network to correct the baseline DFT energies and forces. These electronic descriptors encode much more information than local atomic environments, allowing a simple neural network to reach the accuracy required for the problem of study at a negligible additional cost. The balance between accuracy and efficiency is determined by the baseline simulation. This is shown in results where high level quantum chemical accuracy is obtained for simulations of liquid water at standard DFT cost or where high level DFT-accuracy is achieved in simulations with a low-level baseline DFT calculation at a significantly reduced cost.
The link between coherence echoes and mode locking
Authors: Eydam Sebastian , Wolfrum Matthias
Published: October 2019

We investigate the appearance of sharp pulses in the mean field of Kuramoto-type globally-coupled phase oscillator systems. In systems with exactly equidistant natural frequencies, self-organized periodic pulsations of the mean field, called mode locking, have been described recently as a new collective dynamics below the synchronization threshold. We show here that mode locking can appear also for frequency combs with modes of finite width, where the natural frequencies are randomly chosen from equidistant frequency intervals. In contrast to that, so-called coherence echoes, which manifest themselves also as pulses in the mean field, have been found in systems with completely disordered natural frequencies as a result of two consecutive stimulations applied to the system. We show that such echo pulses can be explained by a stimulation induced mode locking of a subpopulation representing a frequency comb. Moreover, we find that the presence of a second harmonic in the interaction function, which can lead to the global stability of the mode-locking regime for equidistant natural frequencies, can enhance the echo phenomenon significantly. The nonmonotonic behavior of echo amplitudes can be explained as a result of the linear dispersion within the self-organized mode-locked frequency comb. Finally, we investigate the effect of small periodic stimulations on oscillator systems with disordered natural frequencies and show how the global coupling can support the stimulated pulsation by increasing the width of locking plateaus.
A direct transition to chaos in hysteretic systems with focus dynamics
Authors: Esteban M. , Ponce E. , Torres F.
Published: October 2019

A specific transition to chaos is detected in the study of periodic orbits of hysteretic systems with symmetry and dynamics of focus type. The corresponding bifurcation is rigorously justified by resorting to the analysis of transition maps, whose mathematical expressions are adequately derived. It is shown that, depending on a parameter related to the location of equilibria, such transition maps can pass from being a smooth function to a discontinuous, piecewise-smooth function. We deal with the intermediate situation for which the transition map is continuous but nonsmooth. Using a second parameter, and previous known results on chaotic maps, we show in a rigorous way the existence of a chaos boundary crisis bifurcation, where the transition from a configuration without periodic orbits to another with bounded chaotic solutions occurs.
Characterization of non-linearities through mechanical squeezing in levitated optomechanics
Authors: Setter Ashley , Vovrosh Jamie , Ulbricht Hendrik
Published: October 2019

We demonstrate a technique to estimate the strength of nonlinearities present in the trapping potential of an optically levitated nanoparticle. By applying a brief pulsed reduction in the trapping laser power of the system such as to squeeze the phase space distribution and then matching the time evolution of the shape of the phase space distribution to that of numerical simulations, one can estimate the strength of the nonlinearity present in the system. We apply this technique to estimate the strength of the Duffing nonlinearity present in the optical trapping potential.
Ligand induced anomalous emission shift of size-controlled CsPbBr3 nanocrystals
Authors: Kong Xiaobo , Xu Fan , Wang Wenzhi , Juan Fangying , Wu Yangqing , Li Xiaoman , Li Jinkai , Chen Xin , Cao Bingqiang
Published: October 2019

CsPbX3 perovskite nanocrystals (NCs) have attracted much attention from researchers because of their excellent photoelectric properties like high quantum yield, large absorption cross section, and simple preparation process. The addition of ligands in the synthesis process has a significant effect on the microstructure and photophysical properties of solution-processed NCs, which needs further extensive studies. In this Letter, the effects of ligand electronegativity on the size and photoluminescence (PL) properties of CsPbBr3 NCs were reported. One is typical oleic acid with weak electronegativity, and another is 2-acrylamide-2-methylpropionic sulfonic acid with strong electronegativity. The third is their typical mixture with a molar ratio of 1:1. With the increase in ligand electronegativity, the size of CsPbBr3 NCs increases significantly. However, in contrast to the traditional quantum size confinement effect, the PL peak exhibits an abnormal blue shift gradually and the ligand passivation effect on NC surface defects also becomes more significant. The physical mechanism of this anomalous PL shift phenomena of CsPbBr3 NCs was investigated using the time-resolved PL spectrum and transient absorption spectrum.
Dynamics of self-reinforcing matter-wave in gravito-optical surface trap
Authors: Sekh Golam Ali , Kalikotay Pallavi
Published: October 2019

We consider matter-wave solitons/oscillons in the presence of gravito-optical surface traps within the framework of mean-field equations. We pay special attention to the dynamics of both solitons and oscillons against the reflecting platform, the position of which can either be varied periodically or quasiperiodically with time. It is seen that with the temporal variation of reflector’s vertical position, the dynamics of the soliton can change from periodic to quasiperiodic while that of the oscillon can change from regular to chaotic. We find that the transition from regular to chaotic motion is prominent in Poincaré maps for different relevant recurrence times.
Simultaneous determination of thermal diffusivity and thermal conductivity of a thin layer using double modulated thermal excitations
Authors: Alaili Kamal , Ordonez-Miranda Jose , Ezzahri Younès
Published: October 2019

A theoretical model is developed to determine simultaneously and in different ways thermal diffusivity and thermal conductivity of thin layers. This is done by using the accurate expression of the temperature distribution derived from the parabolic heat equation when the front surface of the thin layer is excited by a periodic heat flux, while the rear surface is maintained at one of three different types of boundary conditions: modulated periodic heat flux, modulated temperature, or constant temperature. Our approach exploits the modulation frequencies at which the normalized front surface temperature reaches its first maximum and first minimum. It is shown that (i) these characteristic frequencies can be used to obtain the thermal diffusivity of the finite layer under three different types of boundary conditions. (ii) The ratio between the values of the maxima and minima of the temperature can be utilized to determine the thermal conductivity of the finite layer. These two thermal properties are sensitive to the nature of the boundary conditions as well as the modulation frequency of the heat excitation. This paper provides a theoretical basis for the determination of the thermal diffusivity and thermal conductivity of the finite layer using laser-based heating photothermal techniques.
Influence of the space charge of an ion beam on the time-of-flight diagnostics of its composition
Authors: Pushkarev A. , Zhu X. P. , Zhang C. C. , Prima A. , Li Y. , Egorova Yu. , Lei M. K.
Published: October 2019

The results of time-of-flight diagnostics of the composition of high-intensity pulsed ion beams are presented. The experiments were performed on a diode of focusing and flat geometry, in the mode of self-magnetic insulation of electrons (accelerating voltage 250–300 kV, pulse duration 120 ns, ion current density 20–300 A/cm2), and a focusing diode in an external magnetic insulation mode (300 kV, 80 ns, 100–200 A/cm2). A delay in the registration of protons by 40–50 ns (on the drift path 14–16 cm) was found in the absence of a delay in the registration of heavy ions. It has been shown that this delay can be related to the deceleration of light ions during the transport from the diode to a collimated Faraday cup. This effect of spatial compression of the ion beam in the direction of the drift increases its pulse power but complicates the time-of-flight diagnostics of its composition.
The influences of correlated spatially random perturbations on first passage time in a linear-cubic potential
Authors: Li Yongge , Xu Yong , Kurths Jürgen , Duan Jinqiao
Published: October 2019

The influences of correlated spatially random perturbations (SRPs) on the first passage problem are studied in a linear-cubic potential with a time-changing external force driven by a Gaussian white noise. First, the escape rate in the absence of SRPs is obtained by Kramers' theory. For the random potential case, we simplify the escape rate by multiplying the escape rate of smooth potentials with a specific coefficient, which is to evaluate the influences of randomness. Based on this assumption, the escape rates are derived in two scenarios, i.e., small/large correlation lengths. Consequently, the first passage time distributions (FPTDs) are generated for both smooth and random potential cases. We find that the position of the maximal FPTD has a very good agreement with that of numerical results, which verifies the validity of the proposed approximations. Besides, with increasing the correlation length, the FPTD shifts to the left gradually and tends to the smooth potential case. Second, we investigate the most probable passage time (MPPT) and mean first passage time (MFPT), which decrease with increasing the correlation length. We also find that the variation ranges of both MPPT and MFPT increase nonlinearly with increasing the intensity. Besides, we briefly give constraint conditions to guarantee the validity of our approximations. This work enables us to approximately evaluate the influences of the correlation length of SRPs in detail, which was always ignored previously.
Stimulated spin noise in an activated crystal
Authors: Sharipova M. M. , Kamenskii A. N. , Ryzhov I. I. , Petrov M. Yu. , Kozlov G. G. , Greilich A. , Bayer M. , Zapasskii V. S.
Published: October 2019

In spin noise spectroscopy, the magnetic susceptibility spectrum is known to be provided by the spin-system untouched by any external perturbation, or, better to say, disturbed only by its thermal bath. We propose a new version of spin noise spectroscopy, with the detected magnetization (Faraday-rotation) noise being “stimulated” by an external fluctuating magnetic field with a quasiwhite spectrum. An experimental study of the stimulated spin noise performed on a BaF2:U3+ crystal in a longitudinal magnetic field has revealed specific features of this approach and allowed us to identify the Van-Vleck and population-related contributions to the AC susceptibility of the system and to discover unusual magnetic-field dependence of the longitudinal spin relaxation rate in low magnetic fields. It is shown that spectra of the stimulated and spontaneous spin noise, being both closely related to the spin-system magnetic susceptibility, are still essentially different. Distinctions between the two types of the spin-noise spectra and two approaches to spin noise spectroscopy are discussed.
On the origin of drain current transients and subthreshold sweep hysteresis in 4H-SiC MOSFETs
Authors: Rasinger Fabian , Hauck Martin , Rescher Gerald , Aichinger Thomas , Weber Heiko B. , Krieger Michael , Pobegen Gregor
Published: October 2019

In 4H silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs), slow drain current transients and strong sweep hysteresis govern the subthreshold regime, in particular, after negative gate stress. Although these are clearly charge carrier trapping and emission phenomena, a physical model describing the effect to a full extent is missing. In this paper, we investigate a-face n-channel 4H-SiC trench MOSFETs and record drain current transients over seven decades of time for gate voltages below and above threshold. We find clear evidence that the transients result from electron capture rather than from hole emission. Thereby, the time constant for electron capture into interface or near-interfacial defects is broadly distributed and is well characterized by a lognormal distribution. Based on the findings, we propose a physical model that consistently describes the time-dependent measured data in the full gate voltage range. The resulting trap density for the investigated MOSFETs equals 4.2 × 1012 cm–2 with a median electrical capture cross section of 2.5×10−19 cm2. The distribution of capture time constants has a width of 1.6 orders of magnitude.