bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen-doped graphene quantum dots synthesized by femtosecond laser ablation in liquid from laser induced graphene
Authors: Shen Li , Zhou Sikun , Huang Fei , Zhou Hao , Zhang Hong , Wang Shutong , Zhou Shouhuan
Published: December 2021

In this work, graphene quantum dots (GQDs) were synthesized by femtosecond laser ablation in liquid using laser induced graphene as the carbon source. Nitrogen-doped graphene quantum dots (N-GQDs) were successfully synthesized by adding ammonia water to the graphene suspension. The GQDs/N-GQDs structure consist of a graphitic core with oxygen and nitrogen functionalities with particle size less than 10 nm, as demonstrated by x-ray photoelectron spectroscopy, Fourier infrared spectrometer spectroscopy, and transmission electron microscopy. The absorption peak, PL spectrum, and quantum yield of the N-GQDs were significantly enhanced compared with the undoped GQDs. Further, the possible mechanism of synthesis GQDs was discussed. Furthermore, the N-GQDs were used as a fluorescent probe for detection of Fe3+ ions. The N-GQDs may extend the application of graphene-based materials to bioimaging, sensor, and photoelectronic.
Novel electrolyte additive of graphene oxide for prolonging the lifespan of zinc-ion batteries
Authors: Wang Xuyang , Kirianova Alina V , Xu Xieyu , Liu Yanguang , Kapitanova Olesya O , Gallyamov Marat O
Published: December 2021

Aqueous zinc-ion batteries have attracted the attention of the industry due to their low cost, good environmental friendliness, and competitive gravimetric energy density. However, zinc anodes, similar to lithium, sodium and other alkali metal anodes, are also plagued by dendrite problems. Zinc dendrites can penetrate through polymer membranes, and even glass fiber membranes which seriously hinders the development and application of aqueous zinc-ion batteries. To resolve this issue, certain additives are required. Here we have synthesized an electrochemical graphene oxide with novel electrolyte based on tryptophan, which allows to obtain few-layered sheets with a remarkably uniform morphology, good aqueous solution dispersion, easy preparation and environmental friendliness. We used this electrochemical graphene oxide as an additive to the electrolyte for aqueous zinc-ion batteries. The results of phase-field model combined with experimental characterization revealed that the addition of this material effectively promotes the uniform distribution of the electric field and the Zn-ion concentration field, reduces the nucleation overpotential of Zn metal, and provides a more uniform deposition process on the metal surface and improved cyclability of the aqueous Zn-ion battery. The resultant Zn∣Zn symmetric battery with the electrochemical graphene oxide additive affords a stable Zn anode, which provided service for more than 500 h at 0.2 mA cm−2 and even more than 250 h at 1.0 mA cm−2. The Coulombic efficiency (98.7%) of Zn∣Cu half-cells and thus cyclability of aqueous Zn-ion batteries using electrochemical graphene oxide is significantly better compared to the additive-free electrolyte system. Therefore, our approach paves a promising avenue to foster the practical application of aqueous Zn-ion batteries for energy storage.
Ru-decorated gallium nitride nanotubes as chemical sensor for detection of purinethol drug: a density functional theory study
Authors: Menazea A A , Awwad Nasser S , Ibrahium Hala A , Delerkheiroehin P , Ali H Elhosiny
Published: December 2021

We employed density functional B3LYP to inspect the impact of Ru-decoration on a GaN nanotube (GaNNT) sensing performance in detection of purinethol (PT) drug. The interaction of the pristine GaNNT with the PT was found to be weak, and the sensing response is 4.3. Decorating an Ru atom into the GaNNT surface increases the adsorption energy (Ead) of PT from −6.5 to −23.6 kcal/mol. The sensing response significantly rises to 93.6 by Ru-decoration. A short recovery time of 15.7 s is found for the PT desorption from the Ru-decorated GaNNT surface at 298 K. The water solvent reduces Ead of PT to −20.1 kcal mol−1. Thus, it suggests that Ru-decorated GaNNT may be a highly sensitive PT sensor with a short recovery time.
Quantum coherence induced by a flux qubit coupled by a resonator coherent field through a two-photon interaction
Authors: Mohamed A-B A , Hessian H A , Al-Duais F S , Eleuch H
Published: December 2021

The intrinsic decoherence effects on a flux qubit coupled to a resonator through a two-photon interaction where the resonator field is initially in coherent and even coherent states are investigated. The qubit-resonator entanglement and coherence loss (mixedness) of the system and its subsystems are examined using entropy and negativity. The ability of the qubit-resonator interaction to generate quantum coherence (qubit-resonator entanglement and mixedness) is shown to be dependent on the initial cavity non-classicality, detuning, and decoherence. For larger values of the qubit-resonator detuning, the initial resonator non-classicality can enhance the generation and stability of quantum coherence. The decoherence degrades the qubit-resonator entanglement and destroys the sudden death-birth entanglement.
Computational and experimental investigations on electronic and optical response of oxygenated MoS2
Authors: Shakeel Mubashra , Iqbal M Javaid , Iftikhar Mamoor , Farooq Umer , Qureshi Muhammad Tauseef , Hussein A. Wahab M. A , Chand Ram , Affan Hira , Saleem Murtaza
Published: December 2021

The current study is concerned with the first principle investigations of the oxygenated MoS2 to explore the electronic and optical properties. We consider various oxygen concentrations (MoS2, MoS1.75O0.25, MoS1.5O0.5, MoSO) for the prediction of its impact on parameters using PBE-GGA approximation. A noticeable change in parameters has been observed in the visible regime with the introduction of oxygen content in the MoS2 structure. The results of the electronic properties suggest a string role of Mo d-states, S p-states, and O p-states which, however, show variations for various O concentrations near the Fermi level. The optical absorption spectra for oxygenated MoS2 show a blue shift in the visible range compared to the pure MoS2. The effect of oxygen can also be seen in the experimentally prepared MoS2 thin films as the variation of optical behavior can be seen. Refractive index decreases from 2.5 to ∼2. Similarly, absorption graphs show a lack of absorption phenomenon as the oxygen content increases. The role of oxygen brings appreciable changes in the optical parameters over the different energy ranges.
Digraph states and their neural network representations
Authors: Yang Ying , Cao Huaixin
Published: December 2021

With the rapid development of machine learning, artificial neural networks provide a powerful tool to represent or approximate many-body quantum states. It was proved that every graph state can be generated by a neural network. Here, we introduce digraph states and explore their neural network representations (NNRs). Based on some discussions about digraph states and neural network quantum states (NNQSs), we construct explicitly an NNR for any digraph state, implying every digraph state is an NNQS. The obtained results will provide a theoretical foundation for solving the quantum many-body problem with machine learning method whenever the wave-function is known as an unknown digraph state or it can be approximated by digraph states.
An n–n type heterojunction enabling highly efficient carrier separation in inorganic solar cells
Authors: Li Gang , Huang Yuqian , Tang Rongfeng , Che Bo , Xiao Peng , Lian Weitao , Zhu Changfei , Chen Tao
Published: December 2021

Carrier separation in a solar cell usually relies on the p–n junction. Here we show that an n–n type inorganic semiconductor heterojunction is also able to separate the exciton for efficient solar cell applications. The n–n type heterojunction was formed by hydrothermal deposition of Sb2(S,Se)3 and thermal evaporation of Sb2Se3. We found that the n–n junction is able to enhance the carrier separation by the formation of an electric field, reduce the interfacial recombination and generate optimized band alignment. The device based on this n–n junction shows 2.89% net efficiency improvement to 7.75% when compared with the device consisted of semiconductor absorber–metal contact. The study in the n–n type solar cell is expected to bring about more versatile materials utility, new interfacial engineering strategy and fundamental findings in the photovoltaic energy conversion process.
Deep learning reveals personalized spatial spectral abnormalities of high delta and low alpha bands in EEG of patients with early Parkinson’s disease
Authors: Chu Chunguang , Zhang Zhen , Wang Jiang , Liu Shang , Wang Fei , Sun Yanan , Han Xiaoxuan , Li Zhen , Zhu Xiaodong , Liu Chen
Published: December 2021

Objective. Parkinson’s disease (PD) is one of the most common neurodegenerative diseases, and early diagnosis is crucial to delay disease progression. The diagnosis of early PD has always been a difficult clinical problem due to the lack of reliable biomarkers. Electroencephalogram (EEG) is the most common clinical detection method, and studies have attempted to discover the EEG spectrum characteristics of early PD, but the reported conclusions are not uniform due to the heterogeneity of early PD patients. There is an urgent need for a more advanced algorithm to extract spectrum characteristics from EEG to satisfy the personalized requirements. Approach. The structured power spectral density with spatial distribution was used as the input of convolutional neural network (CNN). A visualization technique called gradient-weighted class activation mapping was used to extract the optimal frequency bands for identifying early PD. Based on the model visualization, we proposed a novel quantitative index of spectral characteristics, spatial-mapping relative power (SRP), to detect personalized abnormalities in the spatial spectral characteristics of EEG in early PD. Main results. We demonstrated the feasibility of applying CNN to identify the patients with early PD with an accuracy of 99.87% ± 0.03%. The models indicated the characteristic frequency bands (high-delta (3.5–4.5 Hz) and low-alpha (7.5–11 Hz) frequency bands) that are used to identify the early PD. The SRP of these two characteristic bands in early PD patients was significantly higher than that in the control group, and the abnormalities were consistent at the group and individual levels. Significance. This study provides a novel personalized detection algorithm based on deep learning to reveal the optimal frequency bands for identifying early PD and obtain the spatial frequency characteristics of early PD. The findings of this study will provide an effective reference for the auxiliary diagnosis of early PD in clinical practice.
The Accuracy of the RK-4 and RK-5 Technique as a Numerical Solution to the SEIRS Model of Online Game Addiction on Mathematics Students
Authors: Side Syafruddin , Saman Abdul , Ramadhan Nur Rezky , Sidjara Sahlan
Published: December 2021

This study aims to determine the accuracy of Runge kutta order-4 (RK-4) and order-5 (RK-4) as a solution to the SEIRS numerical model for online game addiction in mathematics students at Universitas Negeri Makassar. The model used in online game addiction is the Suspected-Exposed-Infected-Recovered-Suspected (SEIRS). This is a quantitative research with secondary data obtained from a closed questionnaire where students were given several answer choices. It starts by examining the SEIRS model of online game addiction, before determining general solutions using the RK-4 and RK-5 techniques. The model is then analyzed and simulated using RK-4 and RK-5 techniques, which are compared to determine the most accurate one. The results show that the SEIRS simulation model is accurate for predicting the number of online game addictions. Furthermore, the Runge-Kutta technique can be used to observe the trend of increasing cases of online games among students. The numerical simulation showed that the RK-4 technique is more accurate than the RK-5 when the population is larger. The simulation results of the SEIRS model using MAPLE provided an estimated increase in online game addiction that can be used by students and their parents to limit the number of permits associated with launching online games.
Mathematics Learning for Students with Special Needs During the Covid-19 Pandemic
Authors: Kadarisma G , Juandi D
Published: December 2021

Students with special needs need special attention when learning during this pandemic because of the limitations they have, especially in learning mathematics. Therefore, the purpose of this study is to describe how mathematics learning for children with special needs during the Covid-19 pandemic is implemented. Therefore, the method in this research is the descriptive qualitative method. The data collection technique used in this research is the study of documentation and interviews with respect to their respective guidelines. Qualitative data were obtained through interviews with teachers accompanying inclusive students as key informants. Documentation is done to see an overview of the teaching materials used by the teacher. The subjects in this study were special guidance teachers for special needs students as many as 2 people from 2 different inclusive schools in the city of Bandung. The results of this study are that. At the beginning of the pandemic, Alam Bandung School implemented online learning, but the rules applied at the school became chaotic, students could not focus during video conferencing, and students’ cognitive abilities decreased, especially in mathematics. Therefore, learning is carried out offline even though it is only 3 days filled with therapy, deepening material and assignments for home. At Mutiara Bunda School, at the beginning of the pandemic, online learning was carried out using Google Meetings and task collection through Google Classroom. Teachers design their own learning tools such as home learning guides for each special needs students so that learning objectives can still be achieved even though they are studying from home.
Knot Semantic Logic and Deep Structure of Statements
Authors: Ja’faruddin  , Chen Wen-Haw , Khaerati
Published: December 2021

This article aims to analyze the deep structure of sentences by applying the knot semantic logic principle in the surface structure of the sentences. This article will help to judge some controversial statements that have legal and social effects. The knot semantic logic theory is a novel approach to explaining a literature’s symmetry structure. Chiasm, parallelism, and concentricity are all examples of symmetry structure. This new theory introduces a new method for detecting symmetry in words, sentences, verses, essays, chapters, and entire books. This analysis will use Knot semantic logic point of view. The methodology used in the analysis has two main procedures: (1) classification of the structure and (2) analyzing some examples from some official/formal statements and controversial statements using Paltridge’s classification of thematic progression and knot semantic logic. The result of this research is that the valid argument has surface and Deep Structure. Some fallacies statements such as presumption, generalization, distortion, and deletion have a deep structure that forms ring composition (Type I of knots semantic logic) and parallelizations (Type III of knots semantic logic). This research results generate a new idea about perspective truth, Original perspective domain, and Response perspective domain
“CoVid” Analysis using Online-Based Problem-Solving Approach on Informatics Mathematics Subject
Authors: Ashari N W , Salwah  , Ma’rufi
Published: December 2021

During the COVID-19 pandemic, lecturers carry out online learning and this condition also force student to learn independently. One alternative solution given is online-based problem-solving approach. This approach are suitable implemented in the mathematics Informatics course. The Approach challenges students to be able to express every result of thinking, transform information into various forms of representation, as well as the ability to adapt to online learning during this pandemic. This research is case study research that aims to analyse the Communication Skills, Visual thinking, and Adaptability (COVid) of students in the mathematics informatics course through Online-Based Problem-Solving Approach. This course examines combinatorics and pigeon holes principle. This lesson is useful in the context of making software that requires certain calculations and logic. The subjects of this study were second semester students of the 2020/2021 academic year at the Informatics Study Program at Univeritas Cokroaminoto Palopo. Data was collected by using assignments, questionnaires, and interviews to obtain valid data. The results show that only a few students are able to express every result of thinking, transform information into various forms of representation, as well as the ability to adapt to online learning during this pandemic.
Visualization of hydrodynamic and physico-chemical processes in rotating and vibrating containers
Authors: Kozlov N V , Mosheva E A , Shmyrov A V
Published: December 2021

Variable inertial fields are an efficient way to control the behaviour of hydrodynamic systems. Forces of inertia can be used, for example, to stabilize or destabilize systems with an interface or density gradient, to mix multiphase or non-isothermal fluids. The implementation of this approach means that liquids fill the periodically moving containers. In this paper, the situations are considered when the containers perform either rotation or translational vibrations. Methods for measuring the density and velocity fields of convective flows in reacting hydrodynamic systems are described. Interferometry is used to visualize the density distribution. Particle image velocimetry (PIV) is used to study the structure and velocity of the flows. Optical instruments are installed stationary in the laboratory system. For video recording, a camera shutter is synchronized with the motion of a container, and thus the images are captured in a fixed phase of oscillations or rotation. Constructions of the containers make it possible to illuminate the working volume through transparent walls at different angles or in different planes. They also provide a compensation for the centrifugal pressure and allow interference cells to be used in overload conditions. The successful application of the methods in experimental studies of chemo-hydrodynamic processes is demonstrated.
Reconstruction of the flow structure in a matrix channel based on two-component LDA data
Authors: Philippov M V , Zolotukhin A V , Chokhar I A , Terekhov V V , Terekhov V I , Baranov I N
Published: December 2021

The work is aimed at creating a technique for reconstructing the three-dimensional structure of turbulent flows using data of a two-component laser-Doppler anemometer at the example of a flow in flat coplanar channels. Data of paired measurements by a two-component LDA at two different angles relative to the measurement point are used to obtain information about the three-dimensional structure of the flow. Further, all three components of the velocity vector were calculated using transformations. The developed method is used to measure the velocity field in a coplanar channel.
Propagation of laser beams through curved interfaces of transparent media
Authors: Pavlov I N , Platonova I V , Raskovskaya I L , Yanina G M
Published: December 2021

Mathematical models of propagation of Gaussian, collimated and structured laser beams in transparent optically homogeneous media in the presence of curved interfaces are presented. Experimental techniques which are used for reconstruction of the interfaces profiles are described.
Flow visualization around cylinder under surface discharge action in the still atmosphere
Authors: Ivchenko A V
Published: December 2021

The paper presents the universal gas-discharge system for surface discharge generation on a cylinder body providing PIV experiments and shadow studies. The system enables the flow visualization around cylinder, discharge power consumption measurements and of temperature fields on the cylindrical surface recording. Under surface discharge action on cylindrical surface in the quiescent air, the flow accompanied by the formation of a near-wall vortex structure and a set of the radially-oriented jets is visualized. The observed jets leave the thermal boundary layer and are able to influence to the gas areas located far away. The presented results indicate the effectiveness of the surface discharges use to control gas-dynamic, thermo-physical and mass transfer processes in the vicinity of streamlined bodies such as cylinders.
Investigation of the influence of nonbreaking waves on the turbulence using PIV methods within laboratory modelling of the upper layer ocean dynamics
Authors: Sergeev D A , Kandaurov A A , Troitskaya Yu I
Published: December 2021

The influence of nonbreaking waves on the mixing processes in the upper layer of the ocean during wind-wave interaction was investigated under the conditions of laboratory modeling at the Thermostratified Wind Wave Tank (TSWiWaT) of IAP RAS. Experiments of three types were performed. In the first experiment, shear flow in water was induced using a weak wind to avoid the excitation of surface waves. In the second experiment, in the absence of wind, only a long smooth surface wave was generated using an underwater paddle wavemaker. The third type of experiment combined the conditions of the previous two, i.e. at the same time the wave generator was working and the wind was blowing. In all experiments, the underwater flow characteristics were measured using the PIV method. Vertical profiles of the mean velocity and fluctuations for two components were obtained. It was shown that the presence of waves leads to an increase in the average drift current, as well as, more importantly, on the level of fluctuations over the entire depth of the recorded profile by more than 3 times. This was observed for horizontal and vertical turbulent velocity components both.
Application of convolutional neural networks in optical text recognition to junk data filtering
Authors: Razumov T E , Churikov D V , Kravchenko O V
Published: December 2021

In this paper, the problem of constructing a model for detecting and filtering unwanted spam messages is solved. A fully connected convolutional neural network (FCNN) was chosen as the model of the classifier of unwanted emails in email. It allows you to divide emails into two categories: spam and not spam. The main result of the research is a software application in the C++ language, which has a micro-service architecture and solves the problem of image classification. The app can handle more than 106 requests per minute in real-time.
Neural network classifier for hyperspectral images of skin pathologies
Authors: Vinokurov V , Khristoforova Yu , Myakinin O , Bratchenko I , Moryatov A , Machikhin A , Zakharov V
Published: December 2021

This paper describes the use and results of a neural network classifier trained on a set of hyperspectral images of benign and malignant neoplasms. The analysis is carried out on 2D images extruded from hyperspectral data. The ranges of wavelengths at which the research is carried out is represented by the intervals 530–570 nm and 600–606 nm, which is caused by the assumption that the analysis of the entire spectral range is redundant and the prospect of saving resources. Melanoma, basal cell carcinoma (BCC), nevus and papilloma are accepted as primary classes, as the most dangerous, most common and non-malignant types of neoplasms, respectively. The neural network classifier is based on a three-block VGG network. With a training set included 1944 images, the classification accuracy for 4 types of samples was 92%.
Optimization of the stereo system calibration parameters for photogrammetric measurements in the conditions of field experiments
Authors: Pinchukov V V , Shmatko E V , Bogachev A D , Yu Poroykov A
Published: December 2021

Optical methods for deformation diagnostics and surface shape measurement are often used in scientific research and industry. Most of these methods are based on the triangulation of a set of two-dimensional points from different images corresponding to the three-dimensional points of an object in space. Triangulation is based on the stereo system calibration parameters, which are determined before the experiment. Measurements during conditions with increased vibration loads can lead to a change in the relative position of the cameras of the stereo system (decalibration). This leads to a change in the actual calibration parameters and an increase in the measurement error. This work aims to solve the problem of increasing the measurement accuracy of the photogrammetric method in the case of high vibration loads. For this, it is proposed to use an optimization algorithm for calibration parameters to minimize the reprojection error of three-dimensional points calculated using triangulation. The paper presents the results of a computer simulation of decalibration of a video camera stereo system, an algorithm for optimizing the external parameters of a stereo system, and an assessment of its performance.
Energy efficiency of lighting systems based on acousto-optic filtration
Authors: Beliaeva A S , Romanova G E
Published: December 2021

Designing systems with an acousto-optical filter requires considering its small numerical aperture and crystal size. These features lead to the low efficiency of using the luminous flux, which may be crucial in practical applications of such systems for spectral analysis. The article discusses ways to increase the energy efficiency in different types lighting systems based on acousto-optic filtration.
Acousto-optic devices using acoustic waves refraction
Authors: Polikarpova N V , Chizh I K
Published: December 2021

The methods of acousto-optics provide multiple techniques for controlling optical beam. The technical parameters of corresponding acousto-optic devices are largely determined by the efficiency of acoustic waves generation. In present work we examine the features of elastic waves generation in materials used in acousto-optics. In most of practical applications the elastic wave generation process is implemented through the refraction of elastic waves at the boundary between two anisotropic media. We present a detailed study of the refraction of elastic waves in strongly anisotropic media. We report new refractive effects such as “extraordinary” refraction. In the latter case the change in the direction of the incident acoustic wave does not influence the direction of the energy flow propagation for refracted elastic waves. The configuration of an acousto-optic device using the geometry of unusual refraction in an anisotropic medium is discussed.
Prediction of life time of high-power IR laser diode by resolution of its spectrum to single-mode components
Authors: Berezovskaya N V , Bliznyuk V V , Dolgov A V , Parshin V A , Savinov N S , Selivanov A A , Semenova O I , Tarasov A E
Published: December 2021

The paper proposes a method for predicting the service life of high-power laser diodes used in optoelectronic measuring systems which allow adjusting the thermophysical parameters of the diagnosed flow volume in a certain range of their values. The method based on the analysis of the current dependence of the shape of the line enveloping the laser radiation spectrum after 200 hours of their operation. It is shown that for such an analysis the emission spectrum must be considered as a superposition of the emission spectra of single-mode laser diodes.
Three-dimensional mapping of the optical centers in the bulk of natural diamond by photoluminescent spectroscopy
Authors: Stsepuro N G , Kovalev M S , Krasin G K , Danilov P A , Kudryashov S I
Published: December 2021

Optically active defects in natural diamonds form specific spectral bands in the optical absorption and luminescence spectra and are called optical centers. Optical centers in the visible spectral range and their corresponding defects are called color centers. Spectral absorption and luminescence bands usually occupy several tens of nanometers in the spectral range and often have a complex structure. This spectral structure is unique to each optical center. The stationary broadband UV-MIR characterization of the set of optically active defects in the bulk of natural diamond with a widely varying concentration of impurities was carried out in this work. Comparison of the initial and modified impurity-defect structures of near-surface diamond layers was carried out by the method of cathodoluminescence and cathodoluminescence topography.
Specifics of application of videogrammetric system Vic-3D in aerodynamic experiment
Authors: Gorbushin A R , Kuruluk K A , Kulesh V P , Shvardygulov G E
Published: December 2021

The main objective of this work was testing a possibility of application of commercial videogrammetric system Vic-3D for measuring position and deformation of the aircraft model and its elements in an industrial the TsAGI transonic wind tunnel T-128. The object of research was a model of passenger aircraft with a wingspan of 2010 mm, fixed on the rear sting. The Vic-3D system used for measuring the position and deformation of the aircraft model was applied for the runs with and without flow at the pitch angles range from −
3 to +12 degrees. Model was tested in wind tunnel up to Mach number M = 0.853. An algorithm of working with the Vic-3D system was described in the article, some specifics of obtained results were underlined. An additional program to derive bend and twist deformations of a wing was developed. Results of an experiment were given, errors and inaccuracy were analyzed. Recommendations for using the system Vic-3D in an aerodynamic experiment were given.
Self-oscillations that cause the destruction of intermolecular bonds in the water coolant of a nuclear power plant
Authors: Proskuryakov K N , Anikeev A V
Published: December 2021

The digital acoustic model of a nuclear reactor (DAMNR) is presented as an auto-oscillatory system belonging to a special class of nonlinear dissipative systems capable of generating undamped oscillations. It is established that a water-water power reactor with a turbulent flow of a coolant is an open system of high complexity with a large number of elements, the connections between which are not predetermined, but probabilistic. Elements of the coolant circuit with negative dissipation (negative friction) are identified. It is shown that they self-organize chaotic turbulent pulsations and vortices into ordered wave oscillations, the frequency of which is determined by the Thomson (Kelvin) formula. In radio engineering circuits, an electronic self-oscillating generator with transformer feedback has similar properties. The presence of negative resistance in nonlinear dynamical systems leads to self-organization of chaotic turbulent perturbations and generation of self-oscillations in the form of acoustic standing waves (ASW). On the basis of theoretical and experimental data, the reliability of a previously unknown property of a reactor with connected pipelines - the ability to generate several ASW simultaneously-was confirmed. The use of DAMNR in the design and operation of nuclear power plants allows to identify the sources of ASW occurring in the coolant, the conditions for their occurrence and frequency.
Study and quantitative assessment of the structural inhomogeneities parameters of composite materials
Authors: Chichigin B A , Kokurov A M , Subbotin D E
Published: December 2021

The possibility of determining the size of the delamination region and the depth of its location in non-metallic multilayer weakly conductive materials using a unique pulsed eddy-current equipment by scanning the sample and registering the region of increasing amplitude of the differential signal has been practically confirmed. The nonstationary thermal and holographic interferometry method is used to obtain information on the shape and size of the bundles. For experimental testing, samples were used made of carbon fiber composite materials with artificially created defects in the structure of the material in the form of delaminations of various sizes and shapes.
K-means clustering of zebrafish embryos images acquired with AOTF-based hyperspectral microscope
Authors: Burlakov A B , Shirokov S V , Huang C C , Khokhlov D D
Published: December 2021

Model organism studies are widely implemented in biomedical research fields. Zebrafish is a common and convenient model organism. To provide in vivo investigation of living zebrafish the non-invasive imaging methods are implemented. Hyperspectral imaging utilizing acousto-optic tunable filters is a perspective modality for zebrafish embryos and larvae automated observation. In this paper, the hyperspectral microscope based on the acousto-optical tunable filter is described. Using the hyperspectral image arrays obtained with the described setup, the K-means clustering algorithm is tested. The results obtained for different number of clusters are presented and discussed.
Physiologically based control of the process of gentle light awakening
Authors: Fedortsov A B , Silivanov M O
Published: December 2021

The well-being of a person and the efficiency of his production activities are largely determined by the correspondence of the biorhythms of a person to his working schedule. As it was established at the molecular and genetic level, the main physical factor that allows us to control human biorhythms is light (Nobel Prize 2017). Modern studies of ophthalmologists have found a third type of photoreceptors in human eyes, in addition to rods and cones. These receptors are not intended for receiving images, but primarily for correcting biorhythms, including controlling the process of awakening. The third type of receptors are sensitive mainly in the short-wave, blue region of the visible spectrum. In recent years light-emitting diodes have appeared. However, these devices do not take into account the current requirements for the spectrum of the awakening radiation, and even more so do not allow it to be adjusted during the awakening process according to the necessary program. We offer a technology for gentle awakening of the employee, based on modern concepts of ophthalmology and biorhythmology. The technology uses computer control of the physical factors of awakening-light and sound.
Orthogonal ray scheme: a method for processing interference patterns and reconstructing the shape of a test convex mirror
Authors: Gavlina A E , Novikov D A , Askerko M V
Published: December 2021

This report is devoted to the processing of the interference pattern of the tested mirror, obtained using the orthogonal ray scheme, where the convex testing surface is illuminated by a collimated beam, which is perpendicular to the optical axis of the surface. The interference pattern is created by two wavefronts, one of which is reflected from the mirror, while the other wavefront bypasses the mirror and travels directly to the detector plane. The result of interference pattern processing is a topography map formed by several tangential profiles. The proposed method is suited for large diameter convex spherical and aspherical mirrors and does not require a priori information of surface under the test, such as the vertex radius of curvature and the conical constant. Theoretical foundation of the data processing method are presented.
Radiation hardness of PantherPix hybrid pixel detector
Authors: Dudas D. , Kafka V. , Marcisovsky M. , Neue G. , Marcisovska M. , Prusa P. , Koniarova I. , Semmler M.
Published: December 2021

Hybrid pixel detectors (HPD) are nowadays well known and
widely used in fundamental research, e.g. in high energy physics
experiments. Over the last decade, segmented semiconductor detectors
have also found use in medicine. The total doses received by medical
radiation detectors often reach a significant level (up to several
hundreds of kGy per decade), especially in applications such as
transmission portal in-vivo dosimetry. Such doses might affect
detector properties. Therefore, it is necessary to evaluate their
performance after absorbing a significant radiation dose. PantherPix
is a novel 2D hybrid pixel detector which is designed specifically
for use in radiation therapy. As was concluded in earlier studies,
it is suitable for radiotherapy quality assurance (QA) and portal
dosimetry. In this paper, the PantherPix radiation hardness is
investigated using a 60Co source. The dependence on dose of the
full depletion voltage, leakage current, detector power consumption
and detector response are provided. The PantherPix radiation
tolerance has been shown to be adequate for common cumulative doses
delivered to radiation detectors in radiotherapy over several
decades and its performance has been verified for doses up to 3000
kGy.
A portable cosmic ray detector for school education
Authors: Bomben L. , Capelli S. , Fanzini C. , Lutsenko E. , Mascagna V. , Petroselli C. , Prest M. , Ronchetti F. , Selmi A. , Vallazza E.
Published: December 2021

This article describes the design, assembly and
characterization of a portable cosmic ray detector, developed by the
INSULAB group and suitable for teaching activities aimed at high
school students. It consists of a compact aluminum suitcase
containing three plastic scintillator modules coupled to
photomultipliers, readout by a custom compact electronics chain and
powered by a power bank. The modules operate in coincidence and the
system records the arrival time of each particle and the time over
threshold of the signal of each scintillator module. The data are
acquired and processed by a Raspberry PI connected to a touch screen
display for online monitoring. The procedure implemented for the
determination of the detector efficiency is reported, along with the
results of the measurements of the cosmic ray rate as a function of
the altitude and the zenith angle, performed in the laboratory and
in different locations outdoors.
Experimental 3-dimensional tracking of the dynamics of a single
electron in the Fermilab Integrable Optics Test Accelerator (IOTA)
Authors: Romanov A. , Santucci J. , Stancari G. , Valishev A. , Kuklev N.
Published: December 2021

We present the results of experimental studies on the
transverse and longitudinal dynamics of a single electron in the
IOTA storage ring. IOTA is a flexible machine dedicated to beam
physics experiments with electrons and protons. A method was
developed to reliably inject and circulate a controlled number of
electrons in the ring. A key beam diagnostic system is the set of
sensitive high-resolution digital cameras for the detection of
synchrotron light emitted by the electrons. With 60–130 electrons
in the machine, we measured beam lifetime and derived an absolute
calibration of the optical system. At exposure times of 0.5 s, the
cameras were sensitive to individual electrons. Camera images were
used to reconstruct the time evolution of oscillation amplitudes of
a single electron in all 3 degrees of freedom. The evolution of
amplitudes directly showed the interplay between
synchrotron-radiation damping, quantum excitations, and scattering
with the residual gas. From the distribution of measured
single-electron oscillation amplitudes, we deduced transverse
emittances, momentum spread, damping times, and beam
energy. Estimates of residual-gas density and composition were
calculated from the measured distributions of vertical scattering
angles. Combining scattering and lifetime data, we also provide an
estimate of the aperture of the ring. To our knowledge, this is the
first time that the dynamics of a single electron are tracked in all
three dimensions with digital cameras in a storage ring.
Remark on a promising design of the fissionTPC cathode
Authors: Fu J.Q.
Published: December 2021

The fission Time Projection Chamber (fissionTPC) has been
designed and built to make precision cross-section measurements of
neutron-induced fission by the NIFFTE Collaboration. The signal of
the cathode is implemented as trigger for the fissionTPC that
rejects alpha signal as background and selects only fission fragment
signal to be recorded. This short note is devoted to a discussion of
a promising way to improve the cathode signal performance by
segmenting the planar cathode into two parts. It is shown through
analytic calculations that the new cathode structure has better
signal-to-noise ratio and faster rise time.
An insect-scale robot reveals the effects of different body dynamics regimes during open-loop running in feature-laden terrain
Authors: Schiebel Perrin E , Shum Jennifer , Cerbone Henry , Wood Robert J
Published: December 2021

The transition from the lab to natural environments is an archetypal challenge in robotics. While larger robots can manage complex limb–ground interactions using sensing and control, such strategies are difficult to implement on small platforms where space and power are limited. The Harvard Ambulatory Microrobot (HAMR) is an insect-scale quadruped capable of effective open-loop running on featureless, hard substrates. Inspired by the predominantly feedforward strategy of rapidly-running cockroaches on uneven terrain (Sponberg, 2007), we used HAMR to explore open-loop running on two 3D printed heterogeneous terrains generated using fractional Brownian motion. The ‘pocked’ terrain had foot-scale features throughout while the ‘jagged’ terrain features increased in height in the direction of travel. We measured the performance of trot and pronk gaits while varying limb amplitude and stride frequency. The frequencies tested encompassed different dynamics regimes: body resonance (10–25 Hz) and kinematic running (30–40 Hz), with dynamics typical of biological running and walking, respectively, and limb-transmission resonance (45–60 Hz). On the featureless and pocked terrains, low mechanical cost-of-transport (mCoT) kinematic running combinations performed best without systematic differences between trot and pronk; indicating that if terrain features are not too tall, a robot can transition from homo-to heterogeneous environments in open-loop. Pronk bypassed taller features than trot on the jagged terrain, and higher mCoT, lower frequency running was more often effective. While increasing input power to the robot improved performance in general, lower frequency pronking on jagged terrain allowed the robot to bypass taller features compared with the same input power at higher frequencies. This was correlated with the increased variation in center-of-mass orientation occurring at frequencies near body resonance. This study established that appropriate choice of robot dynamics, as mediated by gait, frequency, and limb amplitude, can expand the terrains accessible to microrobots without the addition of sensing or closed-loop control.
A model-based strategy for quadruped running with differentiated fore- and hind-leg morphologies
Authors: Tseng Kuan-Yu , Lin Pei-Chun
Published: December 2021

This article introduces a model-based strategy for a quadruped robot with differentiated fore- and hind-leg ground reaction force patterns to generate animal-like running behavior. The proposed model comprises a rigid body and two eccentric spring-loaded inverted pendulum (eSLIP) legs with dampers. The eSLIP model extends the traditional SLIP model by adding a bar to offset the spring direction. The proposed two-leg eSLIP (TL-eSLIP) model’s fore- and hind legs were designed to have the same offset magnitude but in opposite offset directions, producing different braking and thrusting force patterns. The TL-eSLIP model’s reference leg trajectories were designed based on the fixed-point motion of the eSLIP model. Additionally, the legs were clock torque-controlled to modulate leg motion and stabilize the model to follow its natural dynamics. The model’s equations for motion were derived, and the model’s dynamic behavior was simulated and analyzed. The simulation results indicate that the model with leg offsets and in either trotting or pronking has differentiated leg force patterns, and it is more stable and has larger basins of attraction than the model without leg offsets. A quadruped robot was built for experimental validation. The experimental results demonstrate that the robot with differentiated legs ran with differentiated ground reaction force patterns and ran more stably than another robot with the same leg morphology.
A straightforward and miniature implementation method of postural synergies to replicate human grasp characteristics accurately and intuitively
Authors: Liu Yuan , Jiang Li , Liu Hong , Ming Dong
Published: December 2021

Postural synergies have great potential for replicating human grasp characteristics, simplify grasp control and reduce the number of hardware actuators required. However, due to their complex mapping relationship and jagged transmission ratio, the implemented mechanisms are always too bulky and loose, which greatly limits their application. With current solutions, the replication accuracy of motion characteristics or intuitive control is compromised, and hitherto no work in the literature has reported the replication errors. To overcome these limitations, we present a novel design framework to determine the actuation configuration, implementation scheme and physical parameters. In this way, the mechanism is miniaturized and can be compactly embedded in the palm of the hand. A self-contained synergistic robot hand with integrated mechanism, sensors and a suitable electrical system is built. The experiments demonstrate that the robot hand can accurately replicate the motion characteristics of two primary synergies, maintain intuitive control to simplify grasp control, has a good capability for anthropomorphic motion and can grasp different objects with versatile grasp functionality.
The potential of seaweed cultivation to achieve carbon neutrality and mitigate deoxygenation and eutrophication
Authors: Gao Guang , Gao Lin , Jiang Meijia , Jian Ao , He Linwen
Published: December 2021

Carbon neutrality has been proposed due to the increasing concerns about the consequences of rising atmospheric CO2. Previous studies overlooked the role of lost particle organic carbon (POC) and excreted dissolved organic carbon (DOC) from seaweed cultivation in carbon sequestration, that is to say, long term carbon storage in the oceanic sediments and in the water. This study assessed the potential of seaweed cultivation to achieve carbon neutrality of China by 2060 using a new method that included lost POC and excreted DOC. Based on the seaweed production in the years 2015–2019 in China, harvested seaweed removed 605 830 tonnes of carbon, 70 615 tonnes of nitrogen and 8 515 tonnes of phosphorus from seawaters annually; farmed seaweed sequestrated 344 128 tonnes of carbon and generated 2533 221 tonnes of oxygen annually. Among the seven farmed seaweeds, Gracilariopsis lemaneiformis has the highest capacities for carbon removal (9.58 tonnes ha−1 yr−1) and sequestration (5.44 tonnes ha−1 yr−1) and thus has the smallest cultivation area required to sequestrate 2.5 Gt CO2 that is annually required to achieve China’s carbon neutrality goal by 2060. The O2 generated by seaweed cultivation could increase dissolved oxygen in seawaters (0–3 m deep) by 21% daily with gas exchange excluded, which could effectively counteract deoxygenation in seawaters. Gracilariopsis lemaneiformis also has the highest N removal capacity while Saccharina japonica has the highest P removal capacity. To completely absorb the N and P released from the fish mariculture, a production level or a cultivation area two and three times larger (assuming productivity remains unchanged) would be required. This study indicates that seaweed cultivation could play an important role in achieving carbon neutrality and mitigating deoxygenation and eutrophication in seawaters. Cultivation cost could be offset to some extent by increased sales of the harvest parts of the seaweed for food and biofuel.