bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular beam epitaxy of two-dimensional semiconductor BiI3 films exhibiting sharp exciton absorption
Authors: Yasunami T. , Nakamura M. , Inagaki S. , Toyoda S. , Ogawa N. , Tokura Y. , Kawasaki M.
Published: December 2021

Bismuth triiodide (BiI3) is a two-dimensional (2D) layered semiconductor with a fairly narrow bandgap (∼2 eV) and strong excitonic absorption near the band edge. Being endowed with a large absorption coefficient in the visible range, BiI3 attracts a growing interest as a potential compound for thin-film optoelectronic devices. Although various growth techniques have been employed so far, thin films with a high enough crystallinity for the solid assignment of the exciton resonances have never been synthesized. Here, we demonstrate molecular beam epitaxy of high-quality BiI3 films by employing a thin buffer layer deposited at a low temperature (30 °C) to make high temperature (70 °C) growth possible. The films fabricated by this two-step method realize a single-crystalline structure and atomically flat surfaces. The absorption spectra of the films exhibit strong and sharp excitonic resonances near the band edge, indicating the high crystallinity of the films comparable to the bulk single crystals. The presently established fabrication process should be widely applicable to other 2D halide thin films and heterostructures, providing ideal platforms for observing unprecedented emergent phenomena.
The gravity-driven migration of a drop in an unsteady Stokes flow
Authors: Qin Y. , Sun R.
Published: December 2021

The motion of a spherical droplet through a fluid driven by gravity is revisited theoretically. Analytical expressions for the translational velocity of the droplet as well as its internal and external flows coupled at their interface and described by the unsteady Stokes equations are derived combining two-point Padé and Padé-type approximants with the Laplace transform. These expressions, involving scaled complementary error functions, are fast and globally convergent to the exact solutions of the equations. The migration of the droplet depends on three non-dimensional parameters, two of which determine the flow patterns inside and outside, and the last is related to the timescale. The analytical solutions reveal that there is a diffusive shear layer of thickness O(t) on either side of the interface in the early stage. Several plots are made to compare migration velocities of the droplet for different parameter sets and changes in the flow field with time.
Oscillations and collective behavior in convective flows
Authors: Gergely A. , Paizs Cs. , Tötös R. , Néda Z.
Published: December 2021

Oscillations and collective behavior in convection-driven fluid columns are investigated and discussed in analogy with similar phenomenon observed for the flickering flames of candle bundles. Experimentally, it is shown that an ascending circular helium gas column performs an oscillation which is similar in several aspects to the oscillation of diffusion flames. Increasing the nozzle diameter leads to a decrease in the oscillation frequency, while increasing the flow rate results in an increase in this frequency. For helium columns oscillating at nearby frequency and placed close to each other, anti-phase synchronization and beating phenomena are observed. A toy-model based on elementary fluid dynamics describes the observed oscillations and leads to frequencies with the proper trend and values in the right order of magnitude.
Interfacial studies on the effects of patterned anodes for guided lithium deposition in lithium metal batteries
Authors: Morey Madison , Loftus John , Cannon Andrew , Ryan Emily
Published: December 2021

The lifetime and health of lithium metal batteries are greatly hindered by nonuniform deposition and growth of lithium at the anode–electrolyte interface, which leads to dendrite formation, efficiency loss, and short circuiting. Lithium deposition is influenced by several factors including local current densities, overpotentials, surface heterogeneity, and lithium-ion concentrations. However, due to the embedded, dynamic nature of this interface, it is difficult to observe the complex physics operando. Here, we present a detailed model of the interface that implements Butler–Volmer kinetics to investigate the effects of overpotential and surface heterogeneities on dendrite growth. A high overpotential has been proposed as a contributing factor in increased nucleation and growth of dendrites. Using computational methods, we can isolate the aspects of the complex physics at the interface to gain better insight into how each component affects the overall system. In addition, studies have shown that mechanical modifications to the anode surface, such as micropatterning, are a potential way of controlling deposition and increasing Coulombic efficiency. Micropatterns on the anode surface are explored along with deformations in the solid–electrolyte interface layer to understand their effects on the dendritic growth rates and morphology. The study results show that at higher overpotentials, more dendritic growth and a more branched morphology are present in comparison to low overpotentials, where more uniform and denser growth is observed. In addition, the results suggest that there is a relationship between surface chemistries and anode geometries.
Perspective on synthesis, structure, and magnetic properties of R–Fe–H hydrides
Authors: Tereshina I. S. , Pankratov N. Yu. , Karpenkov A. Yu. , Gorbunov D. I. , Doerr M. , Paukov M. A. , Tereshina-Chitrova E. A. , Andreev A. V.
Published: December 2021

The structural and magnetic properties of the multicomponent R–Fe–H compounds with a high content of Fe and H are reported. The process of synthesis of the hydrides (R,R′)2Fe14BH5.5 [where R and R′ are light (Nd) and heavy (Dy, Ho, Er, Tm) rare earth metals, respectively] with a maximum hydrogen content is described in detail. The paper also provides insights into the synthesis of single-crystalline hydrides using the example of the R2(Fe,Co)14BH3 series. The hydrides (R,Nd)2Fe14BH5.5, R2(Fe,Co)14BH3, R2(Fe,Al)17H3 have a significantly increased volume as compared to the parent materials. High-field magnetization results of both parent and hydrogenated compounds at low temperatures are presented. Spin–reorientation phase transitions induced by an external magnetic field are observed. The parameter of the intersublattice exchange interaction and the influence of hydrogen on it are estimated within the framework of the mean field theory. The magnetocaloric effect of the compounds with a magnetic compensation point is studied with a special emphasis placed on the change of the sign of the effect.
Mid-infrared photon pair generation in AgGaS2
Authors: Kumar Mohit , Kumar Pawan , Vega Andres , Weissflog Maximilian A. , Pertsch Thomas , Setzpfandt Frank
Published: December 2021

We demonstrate nondegenerate photon pair generation by spontaneous parametric downconversion in a silver gallium sulfide AgGaS2 crystal. By tuning the pump wavelength, we achieve phase matching over a large spectral range. This allows to generate idler photons in the mid-infrared spectral range above a 6 μm wavelength with corresponding signal photons in the visible. Also, we show photon pair generation with broad spectral bandwidth. These results are a valuable step toward the development of quantum imaging and sensing techniques in the mid-infrared.
Theory of vibrational polariton chemistry in the collective coupling regime
Authors: Mandal Arkajit , Li Xinyang , Huo Pengfei
Published: December 2021

We theoretically demonstrate that the chemical reaction rate constant can be significantly suppressed by coupling molecular vibrations with an optical cavity, exhibiting both the collective coupling effect and the cavity frequency modification of the rate constant. When a reaction coordinate is strongly coupled to the solvent molecules, the reaction rate constant is reduced due to the dynamical caging effect. We demonstrate that collectively coupling the solvent to the cavity can further enhance this dynamical caging effect, leading to additional suppression of the chemical kinetics. This effect is further amplified when cavity loss is considered.
Shear-driven drainage of lubricant in a spherical cavity of lubricant-infused surface
Authors: Kim Hae Nyeok , Lee Sang Joon
Published: December 2021

Lubricant-infused surfaces (LISs), whose initial development was inspired by the slippery surface of Nepenthes pitcher plants, have been eliciting considerable attraction. LISs have been extensively investigated during the last decade due to their potential for various applications, including antifouling, self-cleaning, and drag reduction. However, they can lose slipperiness when the outermost lubricant layer is severely depleted by external forces, such as flow-induced shear force. In the current study, we examined the shear-induced depletion of a lubricant impregnated into a spherical cavity exposed to a laminar channel flow. When the depth of interfacial meniscus exceeds a critical value due to depletion of the infused lubricant, the rotational direction of the lubricant flow inside the cavity is changed. This conversion in the lubricant's rotational direction is attributed to the flow separation above the meniscus between the lubricant and the working fluid. The flow separation induces the formation of a vortex and largely increases the drag force, which is an undesirable situation for LISs to achieve a sustainable drag reduction. To identify the unfavorable drag increasing conditions, we examined the critical depth of meniscus, defined as the depth of meniscus at the onset of switch in the rotational direction of the lubricant flow, with varying cavity geometry, flow velocity, and dynamic viscosity of the working fluid. In addition, a simple scaling analysis was conducted by balancing the viscous pressure and capillary pressure to deduce a theoretical prediction of the critical meniscus depth. The experimentally measured results are matched well with the theoretical predictions.
Negligible rate enhancement from reported cooperative vibrational strong coupling catalysis
Authors: Wiesehan Garret D. , Xiong Wei
Published: December 2021

We report the results of an attempt to reproduce a reported cavity catalysis of the ester hydrolysis of para-nitrophenyl acetate due to vibrational strong coupling. While we achieved the same light–matter coupling strength and detuning, we did not observe the reported ten-fold increase in the reaction rate constant. Furthermore, no obvious detuning dependence was observed. The inconsistency with the reported literature suggests that cavity catalysis is sensitive to experimental details beyond the onset of vibrational strong coupling. This indicates that other important factors are involved and have been overlooked so far. We find that more investigation into the limits, key factors, and mechanisms to reliably actualize cavity modified reactions is needed.
Effects of faecal microbiota transplantation on the growth performance, intestinal microbiota, jejunum morphology and immune function of laying-type chicks
Authors: Yu Jing , Zhou Yujie , Wen Qiongyi , Wang Baolin , Gong Haizhou , Zhu Lingyu , Lan Hainan , Wu Bin , Lang Wuying , Zheng Xin , Wu Min
Published: December 2021

Context Recent studies have indicated that the early stage of growth is a critical window for intestinal microbiota manipulation to optimise the immunity and body growth. Faecal microbiota transplantation (FMT) is often used to regulate intestinal microbiota colonisation. Aims The aim of this study was to explore the effect of FMT on the growth performance, intestinal microbiota, jejunum morphology and immune function of newly hatched laying-type chicks. Methods The chicks (Hy-line Brown) were randomly divided into the control group (CON) and FMT group (FMT), which were treated with sterile saline and faecal microbiota suspension of Hy-line Brown breeder hens on Days 1, 3 and 5 respectively. For each group, there were five replications of 12 birds each for 4 weeks. This study investigated the body weight, tibia length, intestinal microflora, jejunum morphology and immune indexes of the chicks. Key results The results showed that the body weight and tibia length of birds in the FMT group were significantly increased at 7, 14 and 21 days of age (P < 0.01). Furthermore, we found that FMT altered the intestinal microbiota community of the birds and improved the richness, evenness, diversity and stability of their intestinal microbiota (P < 0.05). The faecal microbiota of the donor hens and birds that received the transplantation were very similar. The villus height and the ratio of the villus to crypt of the birds in the FMT group were significantly (P < 0.0001) higher than those in the control group. In addition, Spearman’s correlation analysis showed that the villus height of the FMT group showed positive correlation with Bacteroides (P < 0.05), and the villus height and the ratio of the villus to crypt in the FMT group showed positive correlations with Megasphaera (P < 0.05). The birds in the FMT group had no significant difference in intestinal length, immune organ indexes, serum β-defensin and IgA concentrations. Conclusions In summary, FMT can promote the early growth performance and jejunum morphology of laying-type chicks and improve the intestinal microbiota. FMT has no significant effect on the immune function of chicks. Implications FMT may be a potential method to improve the health of chicks to enhance the poultry industry.
Can a return to small ruminants increase profitability and drought resilience in the semiarid rangelands of northern Australia?
Authors: Bowen M. K. , Chudleigh F.
Published: December 2021

Context The semiarid rangelands of northern Australia have high climate variability and a history of suffering periodic severe droughts. To remain viable, livestock businesses in the rangelands need to build resilience to climatic and market variability by regularly producing a profit and increasing wealth. Aims Our aim was to use the farm-management economics framework to conduct a contemporary assessment of the profitability and resilience of alternative livestock enterprises in the semiarid rangelands of northern Australia. Methods Livestock options were examined for a constructed, hypothetical property representative of the central-western Queensland rangelands (16 200 ha; long-term carrying capacity 1071 adult equivalents). First, the profitability of beef cattle, wool sheep, meat sheep and meat goat enterprises was assessed in a steady-state analysis using herd or flock budgeting models. Second, farm-level, partial discounted cash-flow budgets were applied to consider the value of integrating or fully adopting over time several of the alternative enterprises from the starting base enterprise of either a self-replacing (1) beef cattle herd or (2) wool sheep flock. Key results In the steady-state analysis of existing enterprises, meat sheep and rangeland meat goat enterprises produced the greatest rate of return on total capital (3.9 and 3.7% per annum respectively). The operating profit, of all self-replacing herds or flocks, was most sensitive to meat prices. Where full investment in a wild dog exclusion fence around the boundary of the property, and some refurbishment of existing infrastructure, was required to convert from beef to small ruminant production, the investment increased the riskiness and indebtedness of the overall enterprise. This was the case even when the long-term operating profit of the property could be substantially improved, e.g. by a change to rangeland meat goats (extra A$45 700 profit/annum). Conclusions Existing small ruminant enterprises in the semiarid rangelands of Queensland are profitable and resilient alternatives, based on contemporary prices. However, when changing from the predominant beef cattle enterprise, and incurring significant capital costs to do so, financial risk is substantially increased, which has implications for property managers. Implications The farm-management economics framework should be used by individual grazing businesses for their specific circumstances, to support decision-making.
Genome instability drives epistatic adaptation in the human pathogenLeishmania
Authors: Bussotti Giovanni , Piel Laura , Pescher Pascale , Domagalska Malgorzata A. , Rajan K. Shanmugha , Cohen-Chalamish Smadar , Doniger Tirza , Hiregange Disha-Gajanan , Myler Peter J. , Unger Ron , Michaeli Shulamit , Späth Gerald F.
Published: December 2021

Significance

Chromosome and gene copy number variations often correlate with the evolution of microbial and cancer drug resistance, thus causing important human mortality. How genome instability is harnessed to generate beneficial phenotypes and how deleterious gene dosage effects are compensated remain open questions. The protist pathogenLeishmaniaexploits genome instability to regulate expression via gene dosage changes. Using these parasites as a unique model system, we uncover complex epistatic interactions between gene copy number variations and compensatory transcriptomic responses as key processes that harness genome instability for adaptive evolution inLeishmania. Our results propose a model of eukaryotic fitness gain that may be broadly applicable to pathogenic fungi or tumor cells known to exploit genome instability for adaptation.
A comparison in conventional mass measurements SIM.M.M-S6
Authors: García Fernando , Garcí Francisco , Pinzón Orlando , García Sául , Hernandez Rául , Leyton Fernando
Published: December 2021

Main text

The present document reports the results of a bilateral comparison in the calibration of mass standards that was carried out between CESMEC (Chile) and CENAMEP AIP (Panamá).
This comparison was carried out in the following nominal values: 200 mg, 1 g, 50 g, 200 g, 1 kg, 2 kg, and 10 kg.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Localized surface plasmon resonance-enhanced solar-blind Al0.4Ga0.6N MSM photodetectors exhibiting high-temperature robustness
Authors: Kaushik Shuchi , Karmakar Subhajit , Bisht Prashant , Liao Che-Hao , Li Xiaohang , Varshney Ravendra Kumar , Mehta Bodh Raj , Singh Rajendra
Published: December 2021

The appealing properties of tunable direct wide bandgap, high-temperature robustness and chemical hardness, make Al
x
Ga1−x
N a promising candidate for fabricating robust solar-blind photodetectors (PDs). In this work, we have utilized the optical phenomenon of localized surface plasmon resonance (LSPR) in metal nanoparticles (NPs) to significantly enhance the performance of solar-blind Al0.4Ga0.6N metal–semiconductor–metal PDs that exhibit high-temperature robustness. We demonstrate that the presence of palladium (Pd) NPs leads to a remarkable enhancement by nearly 600, 300, and 462%, respectively, in the photo-to-dark current ratio (PDCR), responsivity, and specific detectivity of the Al0.4Ga0.6N PD at the wavelength of 280 nm. Using the optical power density of only 32 μW cm−2 at −10 V, maximum values of ∼3 × 103, 2.7 AW−1, and 2.4 × 1013 Jones are found for the PDCR, responsivity and specific detectivity, respectively. The experimental observations are supported by finite difference time domain simulations, which clearly indicate the presence of LSPR in Pd NPs decorated on the surface of Al0.4Ga0.6N. The mechanism behind the enhancement is investigated in detail, and is ascribed to the LSPR induced effects, namely, improved optical absorption, enhanced local electric field and LSPR sensitization effect. Moreover, the PD exhibits a stable operation up to 400 K, thereby exhibiting the high-temperature robustness desirable for commercial applications.
Polaron dynamics of Bloch–Zener oscillations in an extended Holstein model
Authors: Huang Zhongkai , Somoza Alejandro D , Peng Cheng , Huang Jin , Bo Maolin , Yao Chuang , Li JiBiao , Long Guankui
Published: December 2021

Recent developments in qubit engineering make circuit quantum electrodynamics devices promising candidates for the study of Bloch oscillations (BOs) and Landau–Zener (LZ) transitions. In this work, a hybrid circuit chain with alternating site energies under external electric fields is employed to study Bloch–Zener oscillations (BZOs), i.e. coherent superpositions of BOs and LZ transitions. We couple each of the tunable qubits in the chain to dispersionless optical phonons and build an extended Holstein polaron model with the purpose of investigating vibronic effects in the BZOs. We employ an extension of the Davydov ansatz in combination with the Dirac–Frenkel time-dependent variational principle to simulate the dynamics of the qubit chain under the influence of high-frequency quantum harmonic oscillators. Band gaps emerge due to energy differences in site energies at alternating qubit sites, and are shown to play key roles in tuning band structures and time periodic reconstructions of the wave patterns. In the absence of qubit–phonon interactions, the qubits undergo either standard BZOs or breathing modes, depending on whether the initial wave packet is formed by a broad or narrow Gaussian wave packet, respectively. The BZOs can get localized in space if the band gaps are sufficiently large. In the presence of qubit–phonon coupling, the periodic behavior of BZOs can be washed out and undergo dynamic localization. The influence of an ohmic bath on the dynamics of BZOs is investigated by means of a Markovian master equation approach. Finally, we calculate the von Neumann entropy as a measure of the entanglement between qubits and phonons.
Heisenberg spins on an anisotropic triangular lattice: PdCrO2 under uniaxial stress
Authors: Sun Dan , Sokolov Dmitry A , Waite Richard , Khim Seunghyun , Manuel Pascal , Orlandi Fabio , Khalyavin Dmitry D , Mackenzie Andrew P , Hicks Clifford W
Published: December 2021

When Heisenberg spins interact antiferromagnetically on a triangular lattice and nearest-neighbor interactions dominate, the ground state is 120° antiferromagnetism. In this work, we probe the response of this state to lifting the triangular symmetry, through investigation of the triangular antiferromagnet PdCrO2 under uniaxial stress by neutron diffraction and resistivity measurements. The periodicity of the magnetic order is found to change rapidly with applied stress; the rate of change indicates that the magnetic anisotropy is roughly forty times the stress-induced bond length anisotropy. At low stress, the incommensuration period becomes extremely long, on the order of 1000 lattice spacings; no locking of the magnetism to commensurate periodicity is detected. Separately, the magnetic structure is found to undergo a first-order transition at a compressive stress of ∼0.4 GPa, at which the interlayer ordering switches from a double-to a single-q structure.
Distribution of first-reaction times with target regions on boundaries of shell-like domains
Authors: Grebenkov Denis S , Metzler Ralf , Oshanin Gleb
Published: December 2021

We study the probability density function (PDF) of the first-reaction times between a diffusive ligand and a membrane-bound, immobile imperfect target region in a restricted ‘onion-shell’ geometry bounded by two nested membranes of arbitrary shapes. For such a setting, encountered in diverse molecular signal transduction pathways or in the narrow escape problem with additional steric constraints, we derive an exact spectral form of the PDF, as well as present its approximate form calculated by help of the so-called self-consistent approximation. For a particular case when the nested domains are concentric spheres, we get a fully explicit form of the approximated PDF, assess the accuracy of this approximation, and discuss various facets of the obtained distributions. Our results can be straightforwardly applied to describe the PDF of the terminal reaction event in multi-stage signal transduction processes.
Review on Higgs hidden-dark sector physics
Authors: Lagouri Theodota
Published: December 2021

The Standard Model (SM), while extremely powerful as a description of the strong, electromagnetic and weak interactions, does not provide a natural candidate to explain Dark Matter (DM). Theoretical as well as experimental motivation exists for the existence of a hidden or dark sector of phenomena that couples either weakly or in a special way to SM fields. Hidden sector or dark sector states appear in many extensions to SM to provide a particular candidate DM in the universe or to explain astrophysical observations. If there is such a family of Beyond the Standard Model (BSM) particles and interactions, they may be accessible experimentally at the Large Hadron Collider (LHC) at CERN and at future High Energy Colliders. In this paper, the main focus is given on selected searches conducted at LHC experiments related to Higgs Hidden-Dark Sector Physics. The current constraints and future prospects of these studies are summarized.
Minimizing IL-6 and IL-10 signalling pathway elements using lumping species and parameters
Authors: Rasool Hemn M , Khoshnaw Sarbaz H A
Published: December 2021

There are many cell signalling pathways that include a higher set of elements. Understanding the dynamics of such systems becomes a difficult issue in systems biology. Mathematical approaches with computational simulations provide a wide range to simplify such complex models and to predicate their dynamics. A powerful technique for reducing the complexity of cell signalling pathways is lumping variables and parameters. In this work, we suggest this technique to reduce the number of elements of IL-6 and IL-10 signalling pathways. The reduced model given in this work provides one a better understanding and predicting some model dynamics, and gives accurate approximate solutions. Computational results show that there is a good agreement between the model dynamics for the original and the simplified models.
Pseudo-bounces vs. new instantons
Authors: Espinosa J.R. , Huertas J.
Published: December 2021

Some false vacua do not decay via bounces. This usually happens when a flat direction of the tunneling action due to scale invariance is lifted to a sloping valley by a scale breaking perturbation, pushing the bounce off to infinity. We compare two types of alternative decay configurations that have been proposed recently to describe decay in such cases: pseudo-bounces and new instantons. Although both field configurations are quite similar, we find that the pseudo-bounce action is lower than the new instanton one and describes more faithfully the bottom of the action valley. In addition, pseudo-bounces cover a range of field space wider than new instantons
and, as a result, lead to a decay rate that can be lower than the one via new instantons by orders of magnitude.
Dynamical attractors in contracting spacetimes dominated by kinetically coupled scalar fields
Authors: Ijjas Anna , Pretorius Frans , Steinhardt Paul J. , Garfinkle David
Published: December 2021

We present non-perturbative numerical relativity simulations
of slowly contracting spacetimes in which the scalar field driving
slow contraction is coupled to a second scalar field through an
exponential non-linear σ model-type kinetic interaction.
These models are important because they can generate a nearly
scale-invariant spectrum of super-Hubble density fluctuations fully
consistent with cosmic microwave background observations. We show
that the non-linear evolution rapidly approaches a homogeneous,
isotropic and flat Friedmann-Robertson-Walker (FRW) geometry for a
wide range of inhomogeneous and anisotropic initial conditions.
Ultimately, we find, the kinetic coupling causes the evolution to
deflect away from flat FRW and towards a novel Kasner-like
stationary point, but in general this occurs on time scales that are
too long to be observationally relevant.
Current drive experiments in SST1 tokamak with lower hybrid waves
Authors: Sharma P.K. , Raju D. , Pathak S.K. , Srinivasan R. , Ambulkar K.K. , Parmar P.R. , Virani C.G. , Kumar J. , Sharma S. , Singh C. , Thakur A.L. , Tanna V.L. , Prasad U. , Khan Z. , Raval D.C. , Gupta C.N. , Krishnan B. , Nair S. , Sharma D.K. , Doshi B. , Vasani M. , Mahajan K. , Rajpal R. , Manchanda R. , Asudani K. , Gupta M.K. , Chowdhuri M.B. , Tanna R.L. , SST-1  , Diagnostic Teams
Published: December 2021

The steadystate superconducting tokamak (SST1) is aimed to demonstrate long pulse plasma discharges employing non-inductive current drive by means of lower hybrid current drive (LHCD) system. The major and minor radius of the machine is 1.1 m and 0.2 m, respectively. The LHCD system for SST1 comprises of klystrons, each rated for 0.5 MW-CW rf power at a frequency of 3.7 GHz. The grill antenna comprises of two rows, each row accommodating 32 waveguide elements. Electron cyclotron resonance breakdown assisted Ohmic plasma is formed in SST1 to overcome the issues associated with low loop voltage start-ups. With recent modifications in the poloidal coils configuration, even with narrow EC pulse (∼50 ms), good repeatable and consistent Ohmic plasmas could be produced which helped in carrying out LHCD current drive experiments on SST1. These experiments demonstrated both fully as well as partially driven non-inductive plasma current in SST1 tokamak. Discharges with zero loop voltages were obtained. The interaction of lower hybrid waves with plasma and generation of suprathermal electrons could be established using energy spectra measured by CdTe detectors. Various other signatures like drop in loop voltages, negative loop voltages, spikes in hard x-rays and increase in second harmonic ECE signal, further confirmed the current drive by LHW’s. The beneficial effect of LHW’s in suppressing hard x-rays was also demonstrated in these experiments. The longest discharge of ∼650 ms could be obtained in SST1 with the help of LHW’s. In this paper, the experimental results obtained with LHCD experiments on SST1 is reported and discussed in more details.
International Conference «Marchuk Scientific Readings 2021» (MSR-2021)
Authors: Mikhailov G A , Kabanikhin S I , Laevsky Yu M , Penenko V V , Glinsky B M , Zagorulko Y A , Shishlenin M A , Podkolodnyy N L , Penenko A V
Published: December 2021

Preface

These Conference Proceedings contain the selected papers of the International Conference «Marchuk Scientific Readings 2021» (MSR-2021) held on October 4 - 8, 2021, in Akademgorodok, Novosibirsk, Russia.

The purpose of the «Marchuk Scientific Readings» conference series is to gather specialists in numerical analysis, applied mathematics, mathematical modeling, computational technologies, information systems, artificial intelligence, and machine learning to discuss, identify and systematize current results, applications, and promising directions in computational mathematics and computer science.

Due to the risk of spreading coronavirus infection, the meeting took place virtually. The organizers were located in the Institute of Computational Mathematics and Mathematical Geophysics SB RAS (Novosibirsk, Russia). Morning sessions were devoted to the conference sections’ invited oral (20 minutes) and oral (15 minutes) presentations. The Plenary talks (30 minutes) were delivered on the afternoon sessions. Within the timeframe of a talk, there was a possibility to ask and answer several questions from the audience. Technologically, the meeting was carried out on the Zoom platform. Plenary talks were broadcast on youtube.com. This conference was the second one carried out with the help of the Zoom platform, and most of the technical issues were already solved in the previous year. In pandemic conditions, the virtual conference seems to be the most appropriate format to share the research results without exposing the community to the risk of infection.

List of Program committee is available in this pdf.
Approximate methods for solving amplitude-phase problem for discrete signals
Authors: Boikov I V , Zelina Ya V , Vasyunin D I
Published: December 2021

Methods for solving amplitude and phase problems for one and two-dimensional discrete signals are proposed. Methods are based on using nonlinear singular integral equations. In the one-dimensional case amplitude and phase problems are modeled by corresponding linear and nonlinear singular integral equations. In the two-dimensional case amplitude and phase problems are modeled by corresponding linear and nonlinear bisingular integral equations. Several approaches are presented for modeling two-dimensional problems: 1) reduction of amplitude and phase problems to systems of linear and nonlinear singular integral equations; 2) using methods of the theory of functions of many complex variables, problems are reduced to linear and nonlinear bisingular integral equations. To solve the constructed nonlinear singular integral equations, methods of collocation and mechanical quadrature are used. These methods lead to systems of nonlinear algebraic equations, which are solved by the continuous method for solution of nonlinear operator equations. The choice of this method is due to the fact that it is stable against perturbations of coefficients in the right-hand side of the system of equations. In addition, the method is realizable even in cases where the Frechet and Gateaux derivatives degenerate at a finite number of steps in the iterative process. Some model examples have shown effectiveness of proposed methods and numerical algorithms.
On the minimal residual methods for solving diffusion-convection SLAEs
Authors: Il’in V P , Kozlov D I , Petukhov A V
Published: December 2021

The objective of this research is to develop and to study iterative methods in the Krylov subspaces for solving systems of linear algebraic equations (SLAEs) with non-symmetric sparse matrices of high orders arising in the approximation of multi-dimensional boundary value problems on the unstructured grids. These methods are also relevant in many applications, including diffusion-convection equations. The considered algorithms are based on constructing ATA — orthogonal direction vectors calculated using short recursions and providing global minimization of a residual at each iteration. Methods based on the Lanczos orthogonalization, AT — preconditioned conjugate residuals algorithm, as well as the left Gauss transform for the original SLAEs are implemented. In addition, the efficiency of these iterative processes is investigated when solving algebraic preconditioned systems using an approximate factorization of the original matrix in the Eisenstat modification. The results of a set of computational experiments for various grids and values of convective coefficients are presented, which demonstrate a sufficiently high efficiency of the approaches under consideration.
Simulation of heat transfer with considering permafrost thawing in 3D media
Authors: Karavaev D A , Laevsky Y M
Published: December 2021

An approach to mathematical modeling of heat transfer with a permafrost algorithm in 3D media based on the idea of localizing the phase transition area is considered. The paper presents a problem statement for a non-stationary heat transfer and a description of a numerical method based on a predictor-corrector scheme. For a better understanding of the proposed splitting method, the accuracy order of approximation considering inhomogeneous right-hand side was studied. The phase changes in the numerical implementation of permafrost thawing is considered in the temperature range and requires recalculation of coefficients values of the heat equation at each iteration step with respect to time. A brief description of the parallel algorithm based on a 3D decomposition method and the parallel sweep method is presented. A study of the parallel algorithm implementations using a high-performance computing system of the Siberian Supercomputer Center of the SB RAS was performed. The results of the permafrost algorithm on models with wellbores are also presented.
Identification of argumentative sentences in Russian scientific and popular science texts
Authors: Salomatina N V , Pimenov I S , Sidorova E A
Published: December 2021

In this study we analyze the applicability of specific machine learning algorithms to the task of detecting sentences containing argumentation in Russian text. We employ a collection of scientific and popular science texts with manually annotated argumentation to evaluate the quality of identifying argumentative sentences in terms of precision, recall, and F-measure. The experiment involves three algorithms: MNB, SVM, and MLP. The bag of words model is used for representing texts. Lemmas of words in analyzed sentences serve as features for the classification. We perform the automatic selection of informative features in accordance with Variance and χ2 criteria combined with the weight-based filtration of lemmas (via TF*IDF and EMI). The training set includes around 800 sentences, while the test set contains 180. The MNB algorithm demonstrates the highest F-measure and recall scores on almost all feature sets (maximal values reached equal 68.7% and 89% respectively), while the MLP algorithm shows the best precision for about half of feature selection variations (the maximal value is 72.5%).
Mutation hotspots of SARS-CoV-2 RNA motifs conserved in betacoronaviruses
Authors: Kobalo N S , Kulikov A A , Titov I I
Published: December 2021

The pandemic of the coronavirus infection COVID-19, which began at the end of 2019 and caused by the SARS-CoV-2 virus, has led to unprecedented consequences in the world. By the end of May 2021, in the world there were 167 million infected and 3.5 million died directly from infection [1]. SARS-CoV-2 is a beta coronavirus, so it shares many conserved fragments with other known viruses of this type [2]. Since the beginning of the spread of the COVID-19, one of the important issues of research of the SARS-CoV-2 virus has been the search for its conserved RNA motifs and their functional annotation. These motifs are potential targets for the treatment and diagnosis of a disease caused by the virus. This report examines the structural RNA fragments of SARS-CoV-2, similar to the corresponding fragments in other beta coronaviruses [2]. For these RNA motifs the nucleotide variability during the spread of the virus, depending on their secondary structure, was investigated. All the motifs display the similar background variability although contain hypervariable positions.
Determination of the variable density of the rod from natural frequencies of longitudinal vibrations
Authors: Utyashev I M
Published: December 2021

Rods of various configurations are elements of many structures and machines. Therefore, the acoustic and vibration diagnostics of such parts has been widely developed. The paper considers the problem of determining the variable density of the rod from the natural frequencies of longitudinal vibrations. It is assumed that the density changes along the axis and is described by a polynomial function. This approach allows one to determine the law of density variation from a finite set of eigenvalues. The results of the study can find applications for finding hidden defects in steel and composite rods, which arise during the production process or due to corrosion.
Application of regression in algorithm of nonlinear stochastic adaptation of unstable multidimensional objects
Authors: Kolesnikova S I
Published: December 2021

The results of a study of applicability of kernel estimation in the synergetic control systems for the objects unstable in an open-loop state (without a stabilizing control) have been presented. The effectiveness of kernel estimates has been shown for four nonlinear objects with unstable limiting states. The estimate the effectiveness of embedding the kernel predictive estimate of the state variables of a nonlinear object, subjected to disturbances of an unknown nature, into the system of synergetic control is demonstrated.
Using the inverse distribution function method and the modified superposition method in the NMPUD computer system
Authors: Cherkashin D A , Voytishek A V
Published: December 2021

This paper presents a computer system for modelling one-dimensional random variables NMPUD, developed in the laboratory of mathematical modelling of Lyceum No. 130 in Novosibirsk. The results of the numerical experiments and the considerations justifying the practicability for using in the NMPUD system: the elementary densities constructed by the technology of sequential (inserted) substitutions, the densities representing weighted sums of elementary densities (which can be simulated using the modified discrete superposition method), the algorithms for a piecewise linear approximation of unknown densities using a given sample, the algorithms of the modified superposition method for computational modelling of random variables with piecewise linear densities, are also presented.
Numerical simulation of aerodynamic properties of separable elements of space-rocket systems in the LOGOS software package
Authors: Aksenov S V , Korchazhkin D A , Yu Puzan A , Puzan O A
Published: December 2021

The work describes simulation results of the aerodynamic properties of split elements of the space-rocket systems in the LOGOS software package: the review of the advanced methods for aerodynamic properties has been carried out, the advantages of the computer simulation when solving such problems were demonstrated, verification and validation computations of the simulation problems for the split elements were performed, the produced results were compared with the reference data from available publications. The analysis of the results confirmed the applicability of the LOGOS software package for computing aerodynamic properties of the split elements.
Rotatable LYSO-GAPD DEXA detector for providing improved spatial resolution
Authors: Heo H. , Yang J. , Kang J.
Published: December 2021

A rotatable
lutetium-yttrium-oxyorthosilicate-Geiger-mode-avalanche photodiode
(LYSO-GAPD) DEXA detector that can be configured into either a
normal-resolution or a high-resolution mode, was proposed and
examined. A 3 × 3 × 2 mm3 LYSO was coupled to a
3 × 3 mm2 GAPD. The versatile transformation of the
high-resolution mode was possible by employing the rotating
controller for the DEXA detector on its own axis, and the intrinsic
resolution in this mode was improved by ∼ 33% compared to the
normal-resolution mode. Dual-energy X-ray spectra and imaging
capabilities were evaluated in both acquisition modes. The
respective peak positions of low- and high-energy-beam of
normal-resolution mode (high-resolution mode) were 1330 mV
(1262 mV) and 2347 mV (2267 mV). The respective peak-to-valley
ratios of low- and high-energy-beam of normal-resolution mode
(high-resolution mode) were ∼ 2.8 (∼ 2.9) and ∼ 1.2
(∼ 1.1). Considerable improvements in phantom images such as
overall contrast and fine-spot detectability were observed in the
high-resolution mode. It should be noted that spatial resolution was
improved by reducing the detection-area from 3 × 3 mm2
to 2 × 3 mm2 in the high-resolution mode, but count
rate was also decreased. These results demonstrated that a rotatable
LYSO-GAPD DEXA detector allows to provide high versatility for both
high-resolution mode and normal-resolution mode with a single
detector.
SiPM dynamic range for CEPC scintillator-based electromagnetic calorimeter
Authors: Niu Y. , Shi Y. , Zhao H. , Zhang Y. , Ruan M. , Liu J.
Published: December 2021

A high-granularity scintillator calorimeter readout with
silicon photomultipliers (SiPMs) is an electromagnetic calorimeter
(ECAL) candidate for experiments at the Circular Electron Positron
Collider (CEPC). A critical design parameter of this ECAL candidate
is the dynamic range of the SiPMs. This study investigates the SiPM
dynamic range required for the CEPC scintillator ECAL. A model is
developed on the basis of the operation principles of SiPMs to
describe the response of an SiPM to light pulses within one recovery
period by considering the cross-talk effect, photon detection
efficiency, and number of pixels. The response curve of a
10000-pixel SiPM predicted by the model is consistent with the
measured curve within 2% for an incident light pulse of up to
12000 photons. The intrinsic fluctuations of the SiPM response
naturally exist in this model, and the correction of the saturation
effect in the SiPM response is investigated. Monte Carlo (MC)
simulation shows that the algorithm can restore the response
linearity of an SiPM for an incident light pulse in which the number
of photons is up to around six times the number of SiPM pixels. The
model and correction program are implemented for full simulation of
the ZH production Z → νν,
H → γγ channel to evaluate the impact
of the SiPM dynamic range of the CEPC scintillator ECAL on the
reconstructed Higgs boson mass and the sensitivity to the Higgs
signal in this channel. The results show that the CEPC scintillator
ECAL equipped with no less than 4000 SiPM pixels and operated with a
light yield of 20 photon-electrons per channel for a single minimum
ionizing particle can meet the requirements for Higgs boson
precision measurement in the di-photon channel at the CEPC.
The effect of oil palm trunk particles and composite density on the physical and mechanical properties of rigid polyurethane foam composite
Authors: Munawar S S , Widyanto C D , Hutahean L S , Purnomo D , Subiyanto B , Ismadi  , Syahrir A , Akbar F , Kosasih D P
Published: December 2021

The oil palm trunk (OPT) particle was used as a filler for the manufacture of rigid polyurethane foam composites (RPUFC). The purpose of this research is to investigate the effect of OPT particle content and variation of composite density on the physical and mechanical properties of RPUFC. The RPUFC was created with five different volume fractions of OPT particles (0, 2.5, 5, 7.5, 10 wt%) and three different composite densities (40, 50, 60 kg/m3). The OPT particles, polyols, and isocyanate were mixed, poured and formed in a closed mold. The moisture content (MC), water absorption (WA), compressive strength (CS), screw withdrawal (SW), and internal bonding strength (IB) properties were determined according to JIS A 5908-2003. The flexural strength (FS) properties were determined according to ASTM D790. The physical properties (MC, WA) were increased with increasing OPT particles in the RPUFC. The RPUFC with 2.5% OPT particle was higher in modulus of rupture, modulus of young and CS values compared to RPUFC control. The IB and SW values were increased when 2.5% OPT particles were added to RPUFC. The best PURFCs were produced with the addition of 2.5% particles at a density of 50 and 60 kg/m3.