bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new multipath channel estimation and mitigation using annihilation filter combined tracking loop implementation in software GPS receivers
Authors: Elango G Arul , Jr René 
Published: December 2021

Abstract
The multipath effect causes severe degradation in the positioning of commercial GPS receivers. Due to multipath error, the positioning accuracy could reach a few of 10 m. If the cumulative Multipath delay is less than 0.1–0.35 chips, then it is difficult to mitigate in GPS receivers. This causes severe degradation in GPS signals and can cause a measurement bias. To alleviate this problem, the estimation of multipath parameters using annihilating filter and its mitigation in the GPS tracking loop is proposed in this work. The estimation of randomly generated multipath signals can be performed in the receiver with a lower sampling rate when compared to the larger bandwidth of the GPS baseband signal. Here, the frequency components of the multipath signal in superimposed complex exponentials have been transformed from the time delay and the amplitude of the path observables. The Rayleigh fading model in the urban scenario has been simulated in which the amplitude and the phase of the number of paths (i.e. the frequency component of superimposed complex exponentials) are set and this fading signal is convolved with GPS signal that forms the multipath faded signal. In the GPS receiver post-processing stage, with the help of the annihilation filter, the multipath components are estimated, then an inverse/adaptive filter and compensation technique are further applied to mitigate the multipath component. The mean square error with the different number of paths with noisy environments is analyzed utilizing the cadzow denoising algorithm. The simulation results of the proposed technique employed in the tracking module of the software GPS receiver under severe multipath conditions indicate a substantial enhancement in the performance of the GPS receiver with minimal code and carrier phase error when compared to the least squares and adaptive blind equalization channel techniques. Moreover, the positioning accuracy is also calculated with the inclusion of multipath components in two satellites out of six satellites used in the simulation, the results showed that the annihilation filter improved the mean position accuracy up to 9.3023 m.
Quantitative and nondestructive determination of residual stress for SiO2 thin film by laser-generated surface acoustic wave technique
Authors: Zhang Li , Xiao Xia , Qi Haiyang , Huang Yiting , Qin Huiquan 
Published: December 2021

Abstract
The laser-generated surface acoustic wave (SAW) technique is a promising method to measure the mechanical properties of thin films quickly and nondestructively. Residual stress is inevitable during the processing and manufacturing of integrated circuits, which will have a major impact on the physical and mechanical properties of the thin film materials and cause deterioration to the structural strength. In this study, the SAW technique based method is proposed for quantitative and nondestructive measuring the residual stress in the nanostructured films. The method is verified by the experiment measuring the SiO2 films in the thickness range of 100–2000 nm. The experimental procedures, including signal excitation, reception and processing, are described in detail. By matching the SAW experimental dispersion curve with the calculated theoretical dispersion curve containing the residual stress, the residual stress of the SiO2 films along [110] and [100] crystallographic orientation of the Si wafer is successfully quantified. The determination results are ranged from −65.5 to 421.1 MPa and the stress value increases as the film thickness decreases, revealing the residual stress of the SiO2 film is compressive. Meanwhile, the conventional substrate curvature method as a comparison is used to verify the correctness and superiority of the proposed SAW method for the residual stress determination.
Efficient gradient computation for optimization of hyperparameters
Authors: Xu Jingyan , Noo Frederic 
Published: December 2021

Abstract
We are interested in learning the hyperparameters in a convex objective function in a supervised setting. The complex relationship between the input data to the convex problem and the desirable hyperparameters can be modeled by a neural network; the hyperparameters and the data then drive the convex minimization problem, whose solution is then compared to training labels. In our previous work (Xu and Noo 2021 Phys. Med. Biol.
66 19NT01), we evaluated a prototype of this learning strategy in an optimization-based sinogram smoothing plus FBP reconstruction framework. A question arising in this setting is how to efficiently compute (backpropagate) the gradient from the solution of the optimization problem, to the hyperparameters to enable end-to-end training. In this work, we first develop general formulas for gradient backpropagation for a subset of convex problems, namely the proximal mapping. To illustrate the value of the general formulas and to demonstrate how to use them, we consider the specific instance of 1D quadratic smoothing (denoising) whose solution admits a dynamic programming (DP) algorithm. The general formulas lead to another DP algorithm for exact computation of the gradient of the hyperparameters. Our numerical studies demonstrate a 55%–65% computation time savings by providing a custom gradient instead of relying on automatic differentiation in deep learning libraries. While our discussion focuses on 1D quadratic smoothing, our initial results (not presented) support the statement that the general formulas and the computational strategy apply equally well to TV or Huber smoothing problems on simple graphs whose solutions can be computed exactly via DP.
An overview of tritium retention in dust particles from the JET-ILW divertor
Authors: Otsuka T , Masuzaki S , Ashikawa N , Torikai Y , Hatano Y , Tokitani M , Oya Y , Asakura N , Hayashi T , Tanigawa H , Iwai Y , Widdowson A , Rubel M 
Published: December 2021

Abstract
Tritium (T) retention characteristics in dust collected from the divertor in JET with ITER-like wall (JET-ILW) after the third campaign in 2015–2016 (ILW-3) have been examined in individual dust particles by combining radiography (tritium imaging plate technique) and electron probe micro-analysis. The results are summarized and compared with the data obtained after the first campaign in 2011–2012 (ILW-1). The dominant component in ILW-1 dust was carbon (C) originating from tungsten-coated carbon fibre composite (CFC) tiles in JET-ILW divertor and/or legacy of C dust after the JET operation with carbon wall. Around 85% of the total tritium retention in ILW-1 dust was attributed to the C dust. The retention in tungsten (W) and beryllium (Be) dominated particles was 100 times smaller than the highest T retention in carbon-based particles. After ILW-3 the main component contributing to the T retention was W. The number of small W particles with T increased, in comparison to ILW-1, most probably by the exfoliation and fragmentation of W coatings on CFC tiles though T retention in individual W particles was smaller than in C particles. The detection of only very few Be-dominated dust particles found after ILW-1 and ILW-3 could imply stable Be deposits on the divertor tiles.
Exploration of interacting dynamical dark energy model with interaction term including the equation-of-state parameter: alleviation of the H0 tension
Authors: Guo Rui-Yun , Feng Lu , Yao Tian-Ying , Chen Xing-Yu 
Published: December 2021

Abstract
We explore a scenario of interacting dynamical dark energy model with the interaction term Q including the varying equation-of-state parameter w. Using the data combination of the cosmic microwave background, the baryon acoustic oscillation, and the type Ia supernovae, to global fit the interacting dynamical dark energy model, we find that adding a factor of the varying w in the function of Q can change correlations between the coupling constant β and other parameters, and then has a huge impact on the fitting result of β. In this model, the fitting value of H
0 is lower at the 3.54σ level than the direct measurement value of H
0. Comparing to the case of interacting dynamical dark energy model with Q excluding w, the model with Q including the constant w is more favored by the current mainstream observation. To obtain higher fitting values of H
0 and narrow the discrepancy of H
0 between different observations, additional parameters including the effective number of relativistic species, the total neutrino mass, and massive sterile neutrinos are considered in the interacting dynamical dark energy cosmology. We find that the H
0 tension can be further reduced in these models, but is still at the about 3σ level.
Linear time-delay circuit and stabilizing controller
Authors: Cong Yuhao , Zhang Yong , Hu Guang-Da 
Published: December 2021

Abstract
This paper is concerned with a linear time-delay circuit and its feedback control. We use electronic components such as resistors and capacitors to realize a linear time-delay system. The time-delays are generated by operational amplifiers and single-chip microcomputers. Based on the actual data measured by the oscilloscope, the parameters of the system are estimated using the least square method. Then a comparison study between the waveform image measured by the oscilloscope and the numerical simulation obtained by MATLAB verifies the effectiveness of the parameters estimations of the circuit system. Furthermore, the circuit system is unstable with a large time-delay, a feedback controller is designed to stabilize the circuit system using the optimization method in the literature. Finally, the experimental results in the linear time-delay circuit show the effectiveness of the optimization method.
Experimental demonstration of ghost imaging with speckled light in long-wavelength infrared range
Authors: Khasanov I Sh 
Published: December 2021

Abstract
Infrared imaging with a single-pixel camera can achieve radiometric accuracy not currently available with multi-pixel thermal cameras. One of the actively investigated single-pixel camera technology is ghost imaging. We propose an optical design to experimentally demonstrate classical ghost imaging in the long-wave infrared frequency range with speckled light without using a spatial light modulator. We obtained an example low-quality ghost image and then used the cross-correlation function to identify and explain the main difficulties in ghost imaging with a thermal camera.
Contribution of wave aberrations represented by Zernike polynomials to the cross-correlation function between distorted and actual speckle patterns
Authors: Blagova T V , Khasanov I Sh 
Published: December 2021

Abstract
Speckles are sensitive to the slightest inhomogeneities of the medium, which is used in optical research methods such as speckle interferometry. However, the stochastic nature of propagation of speckle fields complicates their accurate detection and processing. For example, aberrations in the optical system result in the decorrelation of the image of speckles with the actual speckles that are observed in free space. The report will consider the main types of wave aberrations of optical system and their influence on the correlation properties of speckle patterns. The research results can be used to optimize optical systems in which speckles play a significant role, for example, in classical ghost imaging.
Methodology for identifying gaseous constituents of the atmosphere
Authors: Krasnov A E , Ryzhkova D Yu , Vagin V A 
Published: December 2021

Abstract
Methodology for the analysis of concentrations of gaseous composite of atmosphere by the corresponding infrared (IR) spectrum, measured with the help of trajectory spectroradiometers (TSR) is observed. The developed algorithm for mathematical processing of the measurement results is briefly described, including the detection and estimation of the concentrations of the sought gases using the notch filtration of their spectral components, which makes it possible to significantly reduce the concentration identification error. The spectra of various substances in the mid-IR range are considered, and the results of approbation of the technique based on the TSR model with an external high-temperature radiation source on a 1 m path are presented.
Composite thin films based on multilayer carbon nanotubes and calcium phosphate with electrical conductive properties for bone tissue engineering
Authors: Zhovnir S Z , Savelyev M S , Kuksin A V , Kurilova U E , Gerasimenko A Yu , Fedotov A Yu , Lobzhanidze P V , Komlev V S 
Published: December 2021

Abstract
This work is aimed at developing of electrically conductive composite thin films based on calcium phosphates (CP) and multi-walled carbon nanotubes (MWCNT) for bone tissue engineering. A method based on the sputtering of an dispersion of CPs and MWCNTs on a substrate with subsequent exposure to a laser with different power values to form connected networks of nanotubes has been proposed. It is shown that the electrical conductivity of CP/MWCNT films reaches high values for dispersions with a MWCNT concentration of 1 mg/ml when exposed to laser radiation with a power of 2.1–3.0 W. It was found that ablation areas of CPs and MWCNTs as a result of exposure to a high-power laser are found in areas of the film with increased resistance.
Problems and methods of a closed-loop blood glucose control system construction
Authors: Litinskaia E L , Pozhar K V , Zhilo N M 
Published: December 2021

Abstract
The automation of the insulin therapy in the closed-loop blood glucose control system is accompanied by such problems as delays of the feedback and the controlling action effect on blood glucose dynamics, difficulties in low and high glucose levels advance detection and timely compensation, a human factor, complexity of a mathematical model of control object building, evaluation of blood glucose control efficiency. In the paper, these automation problems and methods for their compensation are considered. The closed-loop system based on the model predictive control, adaptive adjustment of the controlling action and decision-making support was developed. Experimental testing with UVA/Padova Type 1 Diabetes Mellitus Simulator showed that the application of suggested methods in the closed-loop allows increasing the efficiency of the blood glucose maintaining in the target range.
Lumped parameter model of the cardiovascular system with baroreflex
Authors: Rubtsova E , Telyshev D 
Published: December 2021

Abstract
The patient’s activity directly affects the state of the cardiovascular system (CVS). One of the mechanisms contribute to the regulation of the arterial blood pressure is the baroreflex. It is maintains an optimal level of the arterial pressure as a response to changes in the patient’s activity. The model developed in this work simulates CVS at the different patient’s activity levels. The model of baroreflex reproduces changes that occur during an increasing level of patient’s activity. The correlation between heart rate (79 bpm –rest, 123 bpm – exercise) and cardiac output (5.1 l/min –rest, 8.2 l/min – exercise) was achieved. The developed model can be used for personal modelling of various states of the CVS. The model parameters possible to apply for individual patient characteristics. For further development, the model can be integrated with the ventricular assist device during the heart failure state in order to study interactions in the biotechnical system.
Investigating the reliability of all-optical switches in transient mode
Authors: Barabanova E A , Vytovtov K A , Vishnevsky V M , Dvorkovich A V , Shurshev V F 
Published: December 2021

Abstract
In this paper the scheme of 8×8 all-optical switch with two duplicating switching elements and the algorithm of its functioning are presented. For calculating the reliability of all-optical switches, the analytical method based on the Markov process theory is presented. This method allows us to calculate reliability indicators of the all-optical switches as downtime coefficient and availability factor in stationary and transient modes and time of transient mode. The results of numerical calculations show that an increase in the number of duplicating elements by one gives decrease in the downtime coefficient by 6 percent, and the time of the transient process is halved in this case.
Application of acoustic microscopy for evaluation of numismatic material
Authors: Petronyuk Y S , Titov S A , Levin V M 
Published: December 2021

Abstract
A new non-destructive express method for assessing the authenticity of numismatic material is considered in the paper. Non-destructive methods of pulsed acoustic microscopy in the frequency range of 50-100 MHz were applied. Samples of silver coins dated 1924 and 1979 were examined. The characteristic values of the longitudinal and transverse sonic velocity of the samples were obtained. The method of hydrostatic weighing was used to measure the density of the metal. It was shown that assessment of the authenticity and the safety degree of coins can also be carried out by revealing the internal defects such as corrosion. Acoustic visualization in the reflection mode allows imaging the offset of the obverse relative to the reverse and to determine the centre of the coin deviation, which also confirms the quality of the minting.
Mathematical modeling of the eddy current testing of delamination cracks in multilayer CFRP objects
Authors: Shkatov P N 
Published: December 2021

Abstract
We propose an approximate mathematical model making it possible to obtain estimates of the change in the eddy current signal under the influence of delamination in multilayer carbon fiber reinforced plastic (CFRP) objects. We give the dependences of the change in the eddy current signal on delamination in the CFRP objects for a new flaw detection method based on the comparison of eddy current signals from CFRP layers grouped by angular orientation.
Assessment automation of road traffic safety with account for road conditions of an individual itinerary
Authors: Skorobogatchenko D A , Borovik V V , Frolovichev A I 
Published: December 2021

Abstract
The paper substantiates the need to develop an automated system for traffic safety assessment in urban agglomerations, taking into account road conditions. The authors suggest a methodology for assessment of road traffic accidents, which makes it possible to take into account a wide range of factors affecting them. The methodology is based on complementing the traditional approach of final accident rate calculation with algorithms for collecting and analyzing data using Big Data tools, in particular, convolutional neural networks, fuzzy neural networks such as ANFIS, and cluster analysis using the k-means method. All accident rates are grouped according to the principle of homogeneity of acquisition of information for their calculation. Further, one of the data processing tools is applied to each group. As a result, labor intensity is reduced and the effectiveness of the application of the method of final accident rates increases. For practical calculations, the authors have developed a client-server application that uses data on geometric characteristics, current traffic situation, weather and climatic effects at the time of the trip along a specific itinerary. By means of application use, the analysis of traffic safety on a number of routes in Volgograd was carried out and the results are presented in comparison with the calculations made via the traditional method. It is shown that the use of information about the current situation on a specific section of the road network in terms of the current time significantly increases the accuracy of calculations.
The decision support system for conducting fire-prevention measures in woodlands
Authors: Sorokin A A , Maltseva N S , Puzankov D S , Shurshev V F , Galimova L V 
Published: December 2021

Abstract
Purpose of the work is to propose provisions for the aggregation of parameters of a climatic and anthropogenic nature. Regulations are necessary to determine the rating of forest areas in terms of fire hazard level. As a result of the study, theoretical provisions for the aggregation of variables have been proposed. Variables are described on different metric scales and affect the final result in different ways. The provisions are based on the methods of the theory of fuzzy sets and fuzzy inference. The computational complex for determining the rating of the forest areas is implemented in the form of a hierarchical system of fuzzy inference. It is based on the Takagi-Sugeno algorithm. Simulation of the complex operation was carried out. As a result, it was concluded that the generated output pattern has a stepped nature. This makes it possible to classify the analyzed elements into state groups. This allows you to solve the problems of planning work on the implementation of preventive and/or preparatory measures to eliminate or prevent forest fires. The prospect of further research is the formation of decision support systems in the control processes organization of forest areas.
Application of methods of multidimensional statistical analysis for the classification of signal fragments during cutting processing
Authors: Belov A V , Trufanov N N , Churikov D V , Kravchenko O V 
Published: December 2021

Abstract
The preliminary processing of the signal coming from the vibration sensor is performed. Spectral analysis methods allow identifying the distinctive zones corresponding to three parameters: the average amplitude of vibrations, the average value of the spectrum, and the complex parameter of the vibration density obtained using interpolation methods. Hence, the vector contains the listed parameters as components produce a vector space, and the equations of separating surfaces in three-dimensional space and classification errors are calculated.
The effect of shape and sizes of particles of wet quartz powders on complex dielectric permittivity in the frequency range of 10 kHz – 10 GHz
Authors: Bobrov P P , Kroshka E S , Rodionova O V 
Published: December 2021

Abstract
The results of experimental studies of complex dielectric permeability of river sand and powders of granules of fused quartz with narrow distributions of particles in size at the frequencies from 10 kHz to 10 GHz are presented. The granule particles are spheres and the sand particles are irregularly shaped. The samples were moistened with distilled water and NaCl salt solution with conductivity of 0.1 and 0.77 S/m. It has been shown that the shape of the particles affects the complex dielectric permittivity (CDP) in the low frequency part of the range only when proportion of the solution is small and its concentration is weak. At full saturation of the samples with the solution and its high concentration, as well as in all cases at frequencies above 100 MHz, the influence of the particle shape is small. In the mid-frequency part of the range (from units to tens of megahertz) in a sample of quartz granules with small particles, there is a strong relaxation process, leading to a significant increase in the real part of the CDP. A similar, but slight increase is observed in samples of sand with larger particles. In the high-frequency range, the effect of the shape and particle sizes is very weak.