bluuebunny/crossref_metadata_2025 huggingface dataset:
Skyrmionics—Computing and memory technologies based on topological excitations in magnets
Authors: Vakili Hamed , Xu Jun-Wen , Zhou Wei , Sakib Mohammad Nazmus , Morshed Md Golam , Hartnett Timothy , Quessab Yassine , Litzius Kai , Ma Chung T. , Ganguly Samiran , Stan Mircea R. , Balachandran Prasanna V. , Beach Geoffrey S. D. , Poon S. Joseph , Kent Andrew D. , Ghosh Avik W.
Published: August 2021

Solitonic magnetic excitations such as domain walls and, specifically, skyrmionics enable the possibility of compact, high density, ultrafast, all-electronic, low-energy devices, which is the basis for the emerging area of skyrmionics. The topological winding of skyrmion spins affects their overall lifetime, energetics, and dynamical behavior. In this Perspective, we discuss skyrmionics in the context of the present-day solid-state memory landscape and show how their size, stability, and mobility can be controlled by material engineering, as well as how they can be nucleated and detected. Ferrimagnets near their compensation points are promising candidates for this application, leading to a detailed exploration of amorphous CoGd as well as the study of emergent materials such as Mn4N and inverse Heusler alloys. Along with material properties, geometrical parameters such as film thickness, defect density, and notches can be used to tune skyrmion properties, such as their size and stability. Topology, however, can be a double-edged sword, especially for isolated metastable skyrmions, as it brings stability at the cost of additional damping and deflective Magnus forces compared to domain walls. Skyrmion deformation in response to forces also makes them intrinsically slower than domain walls. We explore potential analog applications of skyrmions, including temporal memory at low density—one skyrmion per racetrack—that capitalizes on their near ballistic current–velocity relation to map temporal data to spatial data and decorrelators for stochastic computing at a higher density that capitalizes on their interactions. We summarize the main challenges of achieving a skyrmionics technology, including maintaining positional stability with very high accuracy and electrical readout, especially for small ferrimagnetic skyrmions, deterministic nucleation, and annihilation and overall integration with digital circuits with the associated circuit overhead.
Strain-tuning PtSe2 for high ON-current lateral tunnel field-effect transistors
Authors: Kaniselvan Manasa , Yoon Youngki
Published: August 2021

We use full-band quantum transport simulations to show that monolayer platinum diselenide (PtSe2) tunnel field-effect transistors (TFETs) can deliver high ON currents (ION) under biaxial tensile strain, while maintaining a sub-60 mV/dec subthreshold swing. When strained, monolayer PtSe2 develops a lower effective mass and a small gap across which an efficient tunneling can occur, translating to a high ION when used in a TFET channel. At a drain voltage of 0.8 V and OFF current of 1×10−7 μA/μm, a simulated device with a 5% strained channel has an ION > 116 μA/μm, which is three orders of magnitude greater than that of the unstrained unoptimized device. The corresponding I60 is also increased by 600 times. This improvement comes at a reasonable cost of degradation in the OFF state and has a minimal effect on the switching characteristics down to 10 nm channel length. Our results present the mechanical flexibility of 2D materials as a powerful tuning parameter toward their use in high-performance tunneling devices.
Hardness of as-synthesized cubic boron nitride (111) bulk single crystals
Authors: Gao Lihua , Zhang Xiangfa , Wang Mingzhi , Gao Faming
Published: August 2021

The cubic boron nitride is the second most important superhard materials. To date, the effect of crystallographic anisotropy of the {111} plane on the Knoop microhardness of cubic boron nitride single crystals has not been experimentally obtained. Herein, we measure the detailed Knoop hardness and Vickers hardness for the {111} plane of the amber cubic boron nitride. We find that the crystal orientation dependence of Knoop hardness for amber samples is remarkable and has an obvious regular pattern. The Knoop hardness for amber samples shows a minima about 5° from ⟨110⟩ directions, which is different from the traditional viewpoint that the minimum hardness is on ⟨110⟩ directions. Raman spectra of cubic boron nitrides are measured and help us to explain the hardening of samples.
Materials for emergent silicon-integrated optical computing
Authors: Demkov Alexander A. , Bajaj Chandrajit , Ekerdt John G. , Palmstrøm Chris J. , Ben Yoo S. J.
Published: August 2021

Progress in computing architectures is approaching a paradigm shift: traditional computing based on digital complementary metal-oxide semiconductor technology is nearing physical limits in terms of miniaturization, speed, and, especially, power consumption. Consequently, alternative approaches are under investigation. One of the most promising is based on a “brain-like” or neuromorphic computation scheme. Another approach is quantum computing using photons. Both of these approaches can be realized using silicon photonics, and at the heart of both technologies is an efficient, ultra-low power broad band optical modulator. As silicon modulators suffer from relatively high power consumption, materials other than silicon itself have to be considered for the modulator. In this Perspective, we present our view on such materials. We focus on oxides showing a strong linear electro-optic effect that can also be integrated with Si, thus capitalizing on new materials to enable the devices and circuit architectures that exploit shifting computational machine learning paradigms, while leveraging current manufacturing infrastructure. This is expected to result in a new generation of computers that consume less power and possess a larger bandwidth.
An approach combining the lattice Boltzmann method and Maxwell–Stefan equation for modeling multi-component diffusion
Authors: Huang Ju'an , Li Zhiyuan , Li Na , Bao Cheng , Feng Daili , Jiang Zeyi , Zhang Xinxin
Published: August 2021

The lattice Boltzmann method is an appropriate mesoscopic-scale tool for investigating the diffusion processes. However, since the state-of-the-art multi-component diffusion lattice Boltzmann (LB) models are based on the kinetic theory and start from the lattice Bhatnagar–Gross–Krook model, some defects cannot be avoided: they are only suitable for steady flow and there are limitations for setting the velocity and viscosity in lattice units. We devise a new incompressible LB model for ideal gases in solid oxide fuel cells (SOFCs), which is based on the advection–diffusion equation and coupled with the Maxwell–Stefan (M–S) equation by relaxation time. The coupled M–S equation is used for correction, considering the driving force in a multi-component diffusion system. Our LB model is implemented to predict the concentration overpotentials of a porous anode in a SOFC. The overpotentials are calculated from an H2–H2O–Ar ternary mass transport simulation and compared to the corresponding experimental results and several published continuum-scale and LB computations, demonstrating that our model offers a better consistency with the experimental measurement. Moreover, a Stefan tube is simulated for benchmarking against the local parameters; this is compared with the related experimental data and demonstrates the accuracy of our LB model.
Collision rates of permeable particles in creeping flows
Authors: Reboucas Rodrigo B. , Loewenberg Michael
Published: August 2021

Binary collision rates are calculated for the permeable particles undergoing (i) Brownian motion, (ii) gravity sedimentation, (iii) uniaxial straining flow, and (iv) shear flow. Darcy's law is used to describe the flow inside the permeable particles, and no-slip boundary conditions are applied at particle surfaces. A leading-order asymptotic solution of the problem is developed for the weak permeability regime K=k/a2≪1, where k=12(k1+k2) is the mean permeability and a=a1a2/(a1+a2) is the reduced radius; ai, ki (i = 1, 2), respectively, is the radius and permeability of each particle. The resulting collision rates are given by the quadrature of the pair mobility functions for permeable particles in the near-contact lubrication region and size-ratio-dependent parameters obtained from standard hard-sphere pair mobility functions. Collision rates in shear flow vanish below a critical value of the permeability parameter K* that increases with diminishing size ratio. The analogous problem of pair collision rates of particles with small-amplitude surface roughness δa is also analyzed. The formulas for the collision rates of rough particles provide accurate analytical approximations for the collision rates of permeable particles for all four aggregation mechanisms and a wide range of size ratios using an equivalent roughness δ=0.72K2/5.
Nearly touching spheres in a viscoelastic fluid
Authors: Dandekar Rajat , Ardekani Arezoo M.
Published: August 2021

We theoretically investigate the forces and moments acting on two nearly touching spheres immersed in a second-order fluid. We divide the problem into four sub-classes, where each class represents the translational or rotational motion of the spheres either along the line joining the centers or the axis, which is oriented perpendicular to the line joining the centers. Using a regular perturbation solution methodology with the Deborah number as the small parameter, we obtain analytical expressions for the hydrodynamic forces and the moments experienced by the spheres for each sub-class considered. We find that, while the introduction of viscoelasticity does not generate any torques on the spheres, the viscoelastic contribution to force is non-zero and acts along the line joining the sphere centers for each sub-class. For asymmetric sub-classes, the presence of viscoelasticity produces a lift force on the spheres. We validate our method with the reciprocal theorem approach and find our force estimates to be accurate for small sphere separations. The analytical expressions obtained in this study can be utilized in computational schemes to study the behavior of a suspension of particles immersed in a viscoelastic fluid.
The future of smallholder farming in developing countries in the face of climate change: a perspective with a focus on Pakistan
Authors: Wynn P. C. , Warriach H. M. , Iqbal H. , McGill D. M.
Published: August 2021

The fragile balance in the world’s carbon equilibrium through the discovery of cheap carbon-based fuels in the nineteenth century has led to mass industrialisation and an explosion in the world human population, including that of Pakistan. Farmers worldwide will need to adapt their production systems to accommodate global warming and increased climate extremes resulting from these man-made environmental changes. The focus will need to be on smallholder farmers who generate 53% of the world’s food but who are least equipped to accommodate climate change. The most major limitation will be fresh water supply, no more exemplified than in Pakistan as Himalayan snowfall decreases and peak snow melt comes earlier in spring, limiting irrigation water for summer C4 crops such as corn, millet, sorghum and sugarcane. These are destined to replace the traditional C3 crops of wheat and rice, which will not be as suited to climate change conditions resulting from a projected mean 2°C rise in ambient temperature. Smallholder farmers will need to access superior-quality seed for crop cultivars for both human food and animal forage bred to withstand climatic change. Quantitative genetic selection programs for tropically adapted livestock must be implemented with a major focus on Pakistan’s Nili Ravi and Kundhi buffalo, together with Sahiwal cattle servicing the milk consumption needs of Pakistan’s burgeoning population of 211 million. The quality of forage available for livestock emanating largely from crop residues needs to be improved to meet the country’s greenhouse-gas production targets in line with international expectation. The challenge remains for governments to sustain marketing chains that allow them to be profitable when operating in an increasingly hostile environment. The conservation of soil fertility through increased carbon sequestration will be an important imperative. It is likely that females will play a more important role in directing adaptation in these communities. Successful adjustment will be dependent on effective extension programs working with all sectors of the community including males, females and children from all walks of life in both rural and urban environments. Failure to do so will lead to rapid increases in climate refugee numbers, which the world can ill-afford.
A multi-scale assessment of fire scar mapping in the Great Victoria Desert of Western Australia
Authors: Ruscalleda-Alvarez Jaume , Moro Dorian , van Dongen Richard
Published: August 2021

Fire management is increasingly acknowledged as a necessary tool to maintain diversity in desert environments such as the Great Victoria Desert of Australia, but it needs to be informed by accurate fire history data. We compared and assessed the utility of Landsat-derived and Moderate Resolution Imaging Spectroradiometer (MODIS)-derived burnt area mapping (30 m and 250 m resolution, respectively) for sub-regional, landscape and habitat scale management. We did so by using Sentinel-2-derived, 10 m resolution, burnt area mapping as a reference, to determine the most appropriate product to support land management planning. At the landscape scale, Landsat had significantly lower average omission and commission errors (3.4% and 8.0%, respectively) compared with that of MODIS (42.2% and 19.9%, respectively). At the habitat scale, Landsat burnt area percentage was more accurate, in plots of 500 m × 500 m (root mean square error (RMSE) 0.6% to 8.6%), but offered lower accuracy when estimating partially burnt habitat plots of 120 m × 120 m (RMSE 14.1% to 23.9%). Only Landsat-derived fire scar mapping provided enough detail to produce reliable fire history maps to inform fire management and biodiversity conservation operations at a sub-regional scale, landscape scale and a habitat scale of 500 m by 500 m.
α-Synuclein kinetically regulates the nascent fusion pore dynamics
Authors: Nellikka Rohith K. , Bhaskar Bhavya R. , Sanghrajka Kinjal , Patil Swapnali S. , Das Debasis
Published: August 2021

Significance

The accumulation of nonfunctional α-synuclein (α-synFL) oligomers is the hallmark of Parkinson’s disease (PD), affecting millions of people worldwide. Although α-synFLhas a central role in PD, its cellular function is unclear until now. Understanding the normal function of α-synFLis critical to envisage the molecular basis of abnormal cellular secretion under disease conditions. Previous studies indicated that it can regulate various steps of membrane fusion. Fusion pores are the crucial kinetic intermediates during membrane fusion, through which vesicular secretion occurs from different cell types. Here, we describe a function of α-synFLin regulating the microsecond fusion pore transitions. This study offers an insight into how abnormal secretion occurs under pathological conditions in which nonfunctional α-synFLaccumulates.
Noise-induced properties of active dendrites
Authors: van Vreeswijk Carl , Farkhooi Farzada
Published: August 2021

Significance

Neurons integrate input via their dendritic trees, displaying a wide range of nonlinear processing due to their voltage-dependent active calcium channels. We reveal that in vivo–like fluctuating input enhances nonlinearity in a single dendritic compartment and shifts the input–output relation to exhibit nonmonotonous or bistable dynamics. In particular, with the slow activation of calcium dynamics, we analyze noise-induced bistability and its timescales. We further show in a multicompartmental model neuron with realistic synaptic input that noise-induced bistability persists. These noise-induced orders could provide far-reaching implications for the dendritic function in the processing of in vivo–like fluctuating input.
The Fermi–Dirac distribution provides a calibrated probabilistic output for binary classifiers
Authors: Kim Sung-Cheol , Arun Adith S. , Ahsen Mehmet Eren , Vogel Robert , Stolovitzky Gustavo
Published: August 2021

Significance

While it would be desirable that the output of binary classification algorithms be the probability that the classification is correct, most algorithms do not provide a method to calculate such a probability. We propose a probabilistic output for binary classifiers based on an unexpected mapping of the probability of correct classification to the probability of occupation of a fermion in a quantum system, known as the Fermi–Dirac distribution. This mapping allows us to compute the optimal threshold to separate predicted classes and to calculate statistical parameters necessary to estimate confidence intervals of performance metrics. Using this mapping we propose an ensemble learning algorithm. In short, the Fermi–Dirac distribution provides a calibrated probabilistic output for binary classification.
Folding and misfolding of potassium channel monomers during assembly and tetramerization
Authors: Song Kevin C. , Molina Andrew V. , Chen Ruofan , Gagnon Isabelle A. , Koh Young Hoon , Roux Benoît , Sosnick Tobin R.
Published: August 2021

Significance

Ion channels exist in all organisms. Here, we connect the folding of potassium channel monomers to the kinetics of tetramerization. Rather than adopting a native-like conformation once inserted into the bilayer, monomers initially exist as a structurally heterogeneous ensemble in a protein-dense region. This early clustering of monomers may be a general phenomenon that assists in the assembly of multimeric membrane proteins by pre-localizing the subunits. Folding can occur along fast or slow (misfolded) pathways that can be modulated with mutations that trap monomers in a native-like state. In spite of its name, the C-terminal “tetramerization” domain in KcsA does not enhance tetramerization, suggesting it may play another role in channel function.
Proton loss of inner radiation belt during geomagnetic storm of 2018 based on CSES satellite observation*
Authors: Zhang Zhen-Xia , Shen Xu-Hui , Li Xin-Qiao , Wang Yong-Fu
Published: August 2021

The proton distribution in inner radiation belt is often affected by strong geomagnetic storm disturbance. Based on the data of the sun-synchronous CSES satellite, which carries with several high energy particle payloads and was launched in February 2018, we analyzed the extensive proton variations in the inner radiation belt in a wide energy range of 2 MeV– 220 MeV during 2018 major geomagnetic storm. The result indicates that the loss mechanism of protons was energy dependence which is consistent with some previous studies. For protons at low energy 2 MeV–20 MeV, the fluxes were decreased during main phase of the storm and did not come back quickly during the recovery phase, which is likely to be caused by Coulomb collision due to neutral atmosphere density variation. At higher energy 30 MeV–100 MeV, it was confirmed that the magnetic field line curvature scattering plays a significant role in the proton loss phenomenon during this storm. At highest energies > 100 MeV, the fluxes of protons kept a stable level and did not exhibit a significant loss during this storm.
Nonlinear oscillation characteristics of magnetic microbubbles under acoustic and magnetic fields
Authors: Zhao Lixia , Shi Huimin , Bello Isaac , Hu Jing , Wang Chenghui , Mo Runyang
Published: August 2021

Microbubbles loaded with magnetic nanoparticles (MMBs) have attracted increasing interests in multimode imaging and drug/gene delivery and targeted therapy. However, the dynamic behaviors generated in diagnostic and therapeutic applications are not clear. In the present work, a novel theoretical model of a single MMB was developed, and the dynamic responses in an infinite viscous fluid were investigated under simultaneous exposure to magnetic and acoustic fields. The results showed that the amplitude reduces and the resonant frequency increases with the strength of the applied steady magnetic field and the susceptibility of the magnetic shell. However, the magnetic field has a limited influence on the oscillating. It is also noticed that the responses of MMB to a time-varying magnetic field is different from a steady magnetic field. The subharmonic components increase firstly and then decrease with the frequency of the magnetic field and the enhanced effect is related to the acoustic driving frequency. It is indicated that there may be a coupling interaction effect between the acoustic and magnetic fields.
Increasing the efficiency of post-selection in direct measurement of the quantum wave function
Authors: Wen Yong-Li , Zhang Shanchao , Yan Hui , Zhu Shi-Liang
Published: August 2021

Direct weak or strong measurement of quantum wave function based on post-selections has been widely explored; however, the efficiency of the measurement is heavily limited by the success probability of post-selection. Here we propose a modified scheme to directly measure photon–s wave function by simply inserting a liquid crystal plate before the post-selection stage. Numerical simulations demonstrate that our modified method can significantly increase the efficiency of post selection. Our proposal would speed up the quantum wave function measurement with high resolution and high fidelity.
Residual symmetries, consistent-Riccati-expansion integrability, and interaction solutions of a new (3+1)-dimensional generalized Kadomtsev-Petviashvili equation
Authors: Wu Jian-Wen , Cai Yue-Jin , Lin Ji
Published: August 2021

With the aid of the Painlevé analysis, we obtain residual symmetries for a new (3+1)-dimensional generalized Kadomtsev–Petviashvili (gKP) equation. The residual symmetry is localized and the finite transformation is proposed by introducing suitable auxiliary variables. In addition, the interaction solutions of the (3+1)-dimensional gKP equation are constructed via the consistent Riccati expansion method. Particularly, some analytical soliton-cnoidal interaction solutions are discussed in graphical way.
Application of the bi-characteristic method for reconstructing the effective frequency of electron collisions in the ionosphere
Authors: Kryukovsky A S , Lukin D S , Mikhaleva E V , Rastyagaev DV
Published: August 2021

A method has been developed to reconstruct the effective frequency of electron collisions in the Earth’s ionosphere, based on data on the attenuation of short-wave radiation during vertical sounding of the ionosphere by a frequency-modulated radio signal. Numerical modeling was carried out based on the Hamilton-Lukin bi-characteristic method.
Specific features of the propagation of frequency modulated radio signals in the ionospheric plasma in the presence of local inhomogeneities
Authors: Kryukovsky A S , Lukin D S , Popchenko O V , Rastyagaev D V
Published: August 2021

The features of the propagation of frequency-modulated radio signals reflected from the anisotropic ionosphere containing local inhomogeneities of the electron concentration are investigated. On the basis of the Hamilton-Lukin bi-characteristic method, mathematical modeling of vertical sounding ionograms was carried out both in the case of propagation of an ordinary wave and in the case of propagation of an extraordinary wave. The results of numerical simulation are presented.
Testing of generalized Helmholtz equations for gyrotropic waveguides
Authors: Shirapov D Sh , Itigilov G B
Published: August 2021

Universal generalized Helmholtz equations were tested for gyrotropic waveguides with arbitrary orthogonal cross-sectional shapes with arbitrary magnetization and general Helmholtz equations for gyrotropic waveguides with arbitrary orthogonal cross-sectional shapes with longitudinal magnetization, which are obtained from generalized Helmholtz equations. From the general Helmholtz equations for gyrotropic waveguides are derived the partial Helmholtz equations for gyrotropic waveguides with certain orthogonal cross-sectional shapes (in particular: rectangular, round, elliptical) with a specific (longitudinal, normal, tangent) magnetization. General Helmholtz equations for gyrotropic waveguides with arbitrary orthogonal cross-sectional shapes in longitudinal magnetization and partial Helmholtz equations for gyrotropic elliptic waveguides in longitudinal magnetization are used during testing.
Regional and temporal changes in the main parameters of frequency dispersion in wideband transionospheric radio communication channels
Authors: Ivanov D V , Ivanov V A , Ryabova N V , Kislitsin A A
Published: August 2021

We propose a method for carrying out experimental studies into the effect of dispersion in transionospheric radio channel, taking into account system and geophysical factors separately. The method is based on the mathematical model of frequency dispersion, which is distinguished by introducing a reference frequency. This allowed us to separate geophysical and frequency variables in studying dispersion. Experiments were focused on the features of the influence of geophysical factors on the frequency dispersion in wideband channels at the reference frequency. There is presented a rule for its recalculation into different operating frequencies. The features of phase dispersion depending on the latitude of the signal receiver were revealed.
The vertical profile of the refraction coefficient for microwave radiation in the troposphere and its variability
Authors: Kuznetsov A , Seroukhova O , Simakina T , Kryukova S
Published: August 2021

On the basis of data from 8 aerological stations: St. Petersburg, Tallinn, Sukhinichi, Bologoye, Velikiye Luki, Smolensk, Ryazan and Dolgoprudny, the variability of the refractive index vertical profile in the troposphere is shown. It is noted that the presence in the troposphere of inversions of the altitudinal temperature profile and narrow zones with increased and decreased water vapor content leads to sharp changes in the index refractive index gradient and determines the type of radio wave refraction.
Simulation of methane concentration measurements by lidar in a cloudy atmosphere
Authors: Grigorievsky V I , Tezadov J A
Published: August 2021

Simulation of the vertical profile of methane concentration in the Earth’s atmosphere is simulated in the absence of direct visibility on the spacecraft (SC)-Earth surface route. At high latitudes, clouds cover the Earth’s surface for a significant time, so it is important to use all possibilities so that there are no significant windows of uncertainty in data acquisition along the entire path, including the lower troposphere. For modeling purposes the vertical profile of methane concentration was approximated by a sixth-degree polynomial, and the profile was refined by varying its coefficients until is coincide with the experimental data. The proposed method of using the reflected and scattered signal from clouds and cloud formations and extrapolating data along the vertical profile of methane to the entire path in the absence of direct visibility of the Earth’s surface ensures uninterrupted data acquisition, thereby increasing the accuracy and reliability of statistical materials for determining the methane concentration, and, consequently, its influence on the dynamics of the climate in general.
Radiosonde studies of internal waves in the southern near-equatorial atmosphere of the Earth
Authors: Gubenko VN , Kirillovich I A , Andreev V E
Published: August 2021

Radiosonde measurement data of the wind speed, conducted on 28 February and on 15 November 2007, have been used for the internal gravity waves (IGWs) identification and determination of their parameters in the Earth’s lower stratosphere over Cocos Islands (coordinates: latitude –12.04°S and longitude –96.90°E). A wind speed hodograph analysis has shown that observed fluctuations are wave-induced while the wave energy propagates upwards. Using the results of a wind speed hodograph analysis, dispersion equation and polarization relations, we have obtained the magnitudes of key IGW characteristics such as the intrinsic frequency, amplitudes of vertical and horizontal perturbations of the wind speed, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase (and group) speeds, wave kinetic, potential and total energy. An original method for determining the wave ground-based frequency and azimuthal angle of IGW propagation in the Earth’s atmosphere has been proposed. Application of the developed method to radiosonde measurements, conducted on 28 February 2007, has given a possibility to establish that the wave ground-based frequency is equal to 14.0· 10−4 rad/s and it corresponds to the actual wave period T=1.25 hours.
Investigations of the Atmospheric Moisture Contents Variations Using Ground-Based Microwave Radiometers
Authors: Karavaev D M , Shchukin G G
Published: August 2021

The method of microwave radiometry for investigations of the atmospheric water vapor and integrated cloud liquid water content is considered. Some results of experimental studies of temporal and spatial variations in the integrated water vapor and cloud liquid water contents using ground-based microwave radiometers during different meteorological condition as well as during developments of dangerous weather phenomena are presented. The results of the experiments confirm the prospects of using microwave radiometric information for forecasting of dangerous weather events associated with the development of convective clouds and thunderstorms.
Effects of radiation of quantum-structural elements of clouds in remote sensing of the atmosphere Effects of radiation of quantum-structural elements of clouds in remote sensing of the atmosphere
Authors: Ganzha A A , Kuznetsov I E
Published: August 2021

The article shows that clouds and their elements are formed in the atmosphere in the form of large ensembles of quantum-structural (QS) clusters, which are able to radically change the radiation characteristics of the Earth’s atmosphere and other planets. The unique abilities of large ensembles to form fluxes of high-energy particles, antiparticles, and gamma rays (dark lightning) in the atmosphere are explained. Theoretical studies are supported by the results of field and laboratory experiments with quantum-structural filaments (QSF).
Capacities of TEC measurements by the low-cost GNSS receiver based on the u-blox ZED-F9P for ionospheric research
Authors: Kogogin D A , Nasyrov I A , Sokolov A V , Shindin A V , Ryabov A V , Maksimov D S , Zagretdinov R V
Published: August 2021

A prototype of a low-cost GNSS receiver assembled on base of the u-blox ZED-F9P module is described in the paper. The original low-cost GNSS receiver (OGNSS-R) allows made the parallel registration of 184 channels in the entire frequency range (1176 ÷ 1610 MHz) of the main GNSS (GPS, GLONASS, Galileo, Beidou) and recording raw data of carrier-phase, pseudorange (code) and signal strength measurements. The obtained data processing allows to calculate the slant total electron content (TEC), TEC variations and other most popular TEC-based indices of ionospheric activity. The comparative studies of these parameters and similar parameters obtained by simultaneous measurements on the professional geodetic GNSS receiver Trimble Alloy (KZN2 station of the IGS network) were preformed. The analysis showed the median value of the signal strength at the L1 frequency for the KZN2 station are 8% higher than that at the low-cost GNSS receiver based on the u-blox ZED-F9P module (KZN2–48.75 dBHz; OGNSS-R – 45dBHz). For the L2 frequency that difference is less than 2% (KZN2–49.4 dBHz; OGNSS-R – 48.5 dBHz). The median levels of relative slant TEC and TEC-based indexes of the ionospheric activity obtained by the Trimble Alloy receiver at KZN2 station are 25÷50% lower than for the u-blox ZED-F9P receiver. Thus, the using of starter kits such as the simpleRTK2b debug board based on the u-blox ZED-F9P module described in the paper, is really actual for creating a permanent network of GNSS-stations and/or for carrying out field measurements in experimental campaigns.
The Tangential Velocity Estimation Algorithm for Space-borne SAR
Authors: Khramov K K , Tolstov E F , Kostrov V V
Published: August 2021

This article presents a discussion of one of the important areas of application of synthetic aperture radars (SAR) – the moving target indication (MTI) mode. The principle of trajectory signal processing in MTI systems is based on the estimation of the Doppler frequency or phase shift of the echo signals due to the movement of objects. The paper describes an algorithm for estimating the tangential velocity of moving targets for the MTI system based on the use two apertures displaced along trajectory of SAR spacecraft. The structure of the MTI system based on the analysis of phase and amplitude radar images is considered. Further, the amplitude and phase characteristics of the moving target are obtained. The block diagram of the tangential velocity estimation algorithm is given. Simulation has been performed and the features of the operation of this algorithm are presented. The errors in estimating of the target tangential velocity are determined.
Mathematical models of noise characteristics of high-speed digital-to-analog converters of radar signal generators
Authors: Romashov V V , Romashova L V , Doktorov A N , Yakimenko K A , Sochneva N A
Published: August 2021

A mathematical model of the power spectral density of phase noise of high-speed digital-to-analog converters in one side frequency band of tuning is obtained. Calculated using the developed mathematical model of the power spectral density of phase noise of high-speed digital-to-analog converters from Analog Devices in the efficiency mode in the NRZ baseband showed a small error in comparison with the experimental characteristics. It is shown that in the 2 × NRZ oversampling mode, the phase noise level of the high-speed DAC is 7-8 dBc/Hz lower than in the main NRZ operation mode.
High-resolution experimental dual-wavelength remote sensing synthesized aperture radar: technical appearance and flight test results
Authors: Rovkin M E , Ermakov R V , Samuleev M S , Djakov I V , Yu Dostovalov M
Published: August 2021

A model of new high-resolution two-wavelength aviation synthesized aperture radar (SAR) for remote sensing of the Earth, technical appearance of the system and indicators achieved are presented in the article. The technique and results of conducted flight tests of the SAR prototype as well as examples of obtained radar images are given in the work. The achieved new SAR performance at spatial resolution was equal 0.21 m and 0.5 m in X-and L-band respectively with a viewing bandwidth at a maximum resolution of 8.4 km. In the light of the development of the use of UAVs in Russia, it is concluded that the creation of a compact version of high-resolution SAR with a reduced flight ceiling and maximum range is relevant.
Analysis of the directional pattern of a non-equidistant antenna array with a random arrangement of radiating elements in three-dimensional space
Authors: Tersin V V , Bulkin V V
Published: August 2021

A three-dimensional antenna array with a spherical surface was investigated. The channels were randomly placed at array points with a vertical and horizontal step equal to 0.45 wavelengths. For uniform filling of the sphere, the minimum allowable distance between the channels was introduced, depending on the number of channels and the sphere size. The maximum side lobe level depends on the number of channels. To calculate the path difference in a given direction, the coordinate system was rotated so that one of the coordinate axes coincided with the selected direction. To find the radiation pattern, the scalar product of the amplitude-phase distribution vector corresponding to the signal emission direction was calculated by the complex-conjugate vector of the amplitude-phase distribution corresponding to all possible directions of signal arrival from an external source.
Erratum: Embedded system for ultrasonic imaging of under-water concrete structures
Authors: Jain H. , Patankar V.H.
Published: August 2021

Many of the modern concrete structures such as sea-links and bridges are built in water. They require structural health monitoring (SHM) and audit to ascertain the quality and estimation of remaining useful life. To meet these requirements, a single-channel ultrasonic imaging system has been designed and developed to detect defects, porosities and rebar locations inside the Concrete/ Reinforced Cement Concrete (RCC) structures. This real-time and reconfigurable embedded system was evaluated by carrying out under-water imaging of Concrete and RCC test blocks. Conventionally, Ultrasonic Pulse Velocity (UPV) method is being utilized over three decades in Transmit-Receive (T-R) mode to estimate the density and strength of the concrete structure under test. UPV method requires a skill to interpret the data provided by the UPV instrument. The novelty of the single-channel system discussed in this paper is that it is capable of inspecting Concrete/ RCC structures both in Pulse Echo (PE) as well as in T-R mode. An application software has been developed using C# in a visual environment for image acquisition and the control of Data Acquisition (DAQ) hardware has been interfaced to the computer via USB. The imaging system performs data acquisition and coherent averaging of the RF bipolar data to achieve Signal-to-Noise Ratio (SNR) higher than 20 dB. The performance of the system was evaluated by acquiring B-Scan images of the water submerged concrete test blocks having Side Drilled Hole (SDH) and RCC blocks with one as well as two steel rebars, using 54 kHz water immersion transducer in PE mode. The acquired B-Scan images have revealed the internal details of the sample test blocks, resembling the defects generated in the test blocks. High voltage tone burst bipolar pulser with maximum output of (±350 V) has been specifically designed for this system to inspect highly attenuative porous and non-homogeneous Concrete/ RCC materials for the detection of SDH and reinforced steel bars in the concrete test blocks, using B-Scan imaging technique.
The Sensitivity of Maximum Magnitude Range Parameter in Bedrock Acceleration Calculation for 2500 Years of Return Period, Case Study: Bengkulu Province, Indonesia
Authors: Azwar C M , Syahbana A J , Sari A M , Irsyam M , Pamumpuni A , Sadisun I A
Published: August 2021

Infrastructure development such as multi-storey buildings, toll roads, bridges, housing, and others continue to be carried out to improve the economic region. Those things require planning and a good foundation in order to have a durable and earthquake-resistant building. Earthquake is one of the most destructive geological hazards and can trigger other geological hazards, such as landslides, tsunamis, liquefaction, and land subsidence. Bengkulu Province, Indonesia, is one of the susceptible areas to this hazard. The earthquake hazard assessment is important to do to reduce the risk of material and immaterial loss. This study aims to determine the sensitivity of the maximum magnitude range parameter using the probabilistic seismic hazard analysis (PSHA) method using USGS PSHA software. The result obtained from this study were in Bengkulu Province with all earthquake sources show the value of bedrock acceleration with 2500 years of return period in the range 1.2 – 1.5g. The observed sensitivity shows that Bengkulu Province has a sensitivity value in range of 0.01 – 0.03 with the highest value being in Bengkulu City with a value (0.02722) due to uncertainties of maximum magnitude with range of (+0.1) Mw and the fault source indicates that Lebong has a value of (0,05890742).
The Critical Path Method in Construction Project Rescheduling
Authors: Zakia  , Febrianti Dian
Published: August 2021

Generally, Projects have a deadline, which means the completion of the project must be on time because the successful implementation of a project is an important goal for both the project owner. Management involvement is required for executing the project more effectively and efficiently from the beginning of the task, project completion time and cost. The program needed to project scheduling, project completion time and cost. The problem discussed in this study is the CPM calculation result using Microsoft Project, how to identify the critical path and float in each activity with the CPM. The purpose is to obtain the results of time scheduling calculations using Microsoft project-based CPM, to analyze the critical path of the CPM, and to find out activities that have a grace period. Based on shop drawing, SNI analysis is carried out which is the starter to make project schedules with duration calculated from SNI analysis. The calculation result and data input carried out in Microsoft Project create 180 workdays with 22 activities are on a critical trajectory which takes 20,635 hours. After the authors reschedule the project implementation lasted 172 working days, there were 7 activities on the critical trajectory, spending 18,339 hours.
Effect of GGBFS on Compressive Strength, Porosity, and Absorption in Mortars
Authors: Sambowo K A , Ramadhan M A , Igirisa F
Published: August 2021

This research aims to determine the influence of Granulated Blast Furnace Slag (GGBFS) as an ingredient partially added cement in the making of mortar against compressive strength, porosity, and absorption of mortar. This method of research uses experimental methods. The Mortar mixture used is 1 PC: 2 PS and 0.5 cement factor. GGBFS variations are used at 0%, 10%, 20%, 30%, 40%, and 50% of the weight of cement. This research used cubes with a size 5 cm × 5 cm × 5 cm with a sample amount of 36 pieces with a test age of 7 days. The research results gained compressive strength mortar than mortar control, but at a percentage of 30%, GGBFS bagasse ash in a portion of cement has decreased in strength. Compressive strength at the age of 7 days obtained 10.93 MPa; 11.73 MPa; 17.33 MPa; 10.8 MPa; 16.27 MPa, and 16.8 MPa. The compressive strength the maximum average found in the variation of 20% and a variation of 20% GGBFS is a variation that meets the Type M Mortar plan’s compressive strength of 17.2 MPa.
Behavior of Curved Double Steel-Concrete Composite Shear Walls Under Cyclic Loading
Authors: Çobanoğlu Ö , Guo Q
Published: August 2021

In this study, effects of different curved structures on mechanical behavior of curved double steel-concrete composite shear (SC) walls under cyclic loading were investigated numerically. Firstly, the experimental results of a straight SC wall under cyclic loading were used to validate numerical result. After then, curved SC walls were designed in ABAQUS according to different radius-thickness (R/t) ratios (5,10,15,20,25,30,40). In numerical studies, in-plane monotonic response, cycling response, and out-of-plane monotonic response were investigated by changing the loading. The results showed that among all parameters, the R/t ratio:5 has better seismic performance by 11.87% than straight SC wall under cyclic loading. In addition, it was found that when the ratio of the radius of curvature to the section thickness values were greater than 10, curved SC walls behaved as straight SC walls. When the R/t ratio was bigger than 10, the ultimate load and damage of wall load dropped consistently. According to in-plane monotonic response results, R/t ratio:5 has a 13.6% better peak force than straight wall when it is compared with other R/t ratio values. Calculated results showed that although there is no effect in bearing capacity when R/t ≥ 10, it increased by 35.4% when R/t is 5.
Prediction Models of Infrastructure Resilience as a Decision Support System Based on Bayesian Network
Authors: Agustin A D , Adi T J W
Published: August 2021

The impact of climate change is the implication of global warming that affects people around the world, including Indonesia, which is causing more the intensity and type of natural disaster that causes a decrease or malfunction of a city. To reduce the impact of climate change is needed for the application of the concept of resilience. Resilience is the ability to withstand disturbances caused by external factors and the ability to recover if damage occurs. One of the natural disasters is an earthquake is a natural disaster that often occurs in Indonesia and generally causes significant damage to the physical condition of buildings and infrastructure. This study aims to create a prediction model to measure the impact of a disaster as a decision support system such as a mitigation strategy and responses to identify measures that can improve performance infrastructure to meet resilience goals. One of probabilistic methods is the Bayesian Network method. It is a graphical model probabilistic that represents a set of variables and freedom probabilistic usingconditional-probability-table. This research expects as a proposed method of assessing resilience infrastructure to cities in Indonesia when natural disasters occur, especially earthquakes.
The New Analysis of Discrete Element Method Using ARM Processor
Authors: Ma’arif F , Gao Z , Li F , Ghifarsyam H U
Published: August 2021

The discrete element method (DEM) is widely used to predict the motion over time of many particles, such as molecules or soil particles. The computational demands for DEM simulations are significant. Therefore, improved performance could address a spectrum of scientific and engineering applications. This paper proposes an accelerated implementation for the DEM using Advanced of Reduced Instruction Set Computing Machine. The method used in this research is to compare the results of the ARM versus x86 analysis. The case study refers to the investigation conducted by V. Ćmilauer using YADE programming. The results showed that the performance of ARM as a microprocessor was capable of DEM analysis. Furthermore, because the arm stands alone as a system, it runs both Ubuntu and Windows operating systems without affecting each other’s performance and capabilities. Finally, the study will focus on ARM processing as future works.
The Study of Bond Strength of Reinforced Concrete Structures on Severe Environment
Authors: Pramudiyanto  , Widodo S , Sumiyanto J
Published: August 2021

Reinforced concrete is a composite material made up of two components with unequal mechanical behaviour and physical features. This action is produced by the interaction between both of its components, plain concrete and reinforcing bars. In, general, the external load is applied to concrete and to the reinforcing bars receive its part of the load only from the surrounding concrete by bond. So, bond stress is the shear stress acting parallel to an embedded bar on the surface between the bar and the concrete. The aim of this research is to investigate the behaviour of concrete characteristic on severe environment, and the bond strength of steel reinforcement with two different treatments. The concrete compressive strength is taken to be 35 MPa, as recommended on standards. The test commenced are compressive test and bond strength test. The concrete compressive strength, (f’c
) have met the criteria, since the average compressive strength obtained from the test are above 35 MPa. The concrete quality control has a poor-quality control, which has coefficient of variation 10.99% against ACI 214R-11 requirement. The bond strength using painted reinforcement shows the relatively good performance rather than using waterproofed concrete and the bond strength using waterproofed concrete shows relatively flat performance. With the point of view of practical aspect, the waterproofed concrete seems to be more practical rather than painted reinforcement.