bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lumbar Spine Sagittal Mismatch Deformity Negatively Affects Total Knee Arthroplasty Outcomes
Authors: Sheppard William L. , Upfill-Brown Alexander , McKay Kevin M. , Park Howard Y. , Shah Akash , Park Don Y. , Sassoon Adam A. 
Published: February 2021

AbstractThere is currently a paucity of data regarding the potential relationships between preexisting spinal deformity and clinical outcomes following total knee arthroplasty (TKA). We sought to expand upon this deficit. We hypothesize that lumbar sagittal mismatch deformity (MD) will correlate with a decrease in functional outcomes after TKA. This retrospective cohort comparison of 933 TKAs was performed between January 2017 and 2020. TKAs were excluded if they were not performed for primary osteoarthritis (OA) or if preoperative lumbar radiographs were unavailable/inadequate to measure sagittal parameters of interest: pelvic incidence, sacral slope, pelvic tilt, lumbar lordosis, and deformity mismatch. Ninety-four TKAs were subsequently available for inclusion and divided into two groups: those with MD as defined by |PI-LL| > 10 degrees and those without MD. The following clinical outcomes were compared between the groups: total postoperative arc of motion (AOM), incidence of flexion contracture, and need for manipulation under anesthesia (MUA). In total, 53 TKAs met the MD criteria, while 41 did not have MD. There were no significant differences in demographics, body mass index, preoperative knee range of motion (ROM), preoperative AOM, or opiate use between the groups. TKAs with MD were more likely to have MUA (p = 0.026), ROM <0 to 120 (p < 0.001), a decreased AOM by 16 degrees (p < 0.001), and a flexion contracture postoperatively (p = 0.01). Preexisting MD may adversely affect clinical results following TKA. Statistically and clinically significant decreases in postoperative ROM/AOM, increased likelihood of flexion contracture, and increased need for MUA were all noted in those with MD. This is a Level 3 study.
Injection locking and noise reduction of resonant tunneling diode terahertz oscillator
Authors: Hiraoka Tomoki , Arikawa Takashi , Yasuda Hiroaki , Inose Yuta , Sekine Norihiko , Hosako Iwao , Ito Hiroshi , Tanaka Koichiro 
Published: February 2021

We studied the injection-locking properties of a resonant-tunneling-diode terahertz oscillator in the small-signal injection regime with a frequency-stabilized continuous THz wave. The linewidth of the emission spectrum dramatically decreased to less than 120 mHz (half width at half maximum) from 4.4 MHz in the free running state as a result of the injection locking. We experimentally determined the amplitude of injection voltage at the antenna caused by the injected THz wave. The locking range was proportional to the injection amplitude and consistent with Adler’s model. While increasing the injection amplitude, we observed a decrease in the noise component of the power spectrum, which manifests the free-running state, and an alternative increase in the injection-locked component. The noise component and the injection-locked component had the same power at the threshold injection amplitude as small as 5 × 10−4 of the oscillation amplitude. This threshold behavior can be qualitatively explained by Maffezzoni’s model of noise reduction in general limit-cycle oscillators.
Primitive selection of the fittest emerging through functional synergy in nucleopeptide networks
Authors: Bandela Anil Kumar , Wagner Nathaniel , Sadihov Hava , Morales-Reina Sara , Chotera-Ouda Agata , Basu Kingshuk , Cohen-Luria Rivka , de la Escosura Andrés , Ashkenasy Gonen 
Published: February 2021

Significance
Research on the chemical origin of life comprises one of the most exciting topics in contemporary science. Prebiotic chemistry provided evidence that precursors of both nucleic acids and proteins might be formed in the prebiotic environment. Yet, studies on nonenzymatic replication—a central mechanism driving chemical evolution—focused largely on each class of these molecules separately. This paper reveals a successful attempt to replicate simple nucleopeptide chimeras. Most importantly, different mechanisms control the replication of complementary chimeras, leading to a clear selection of one over the other. We propose that related processes may have led to the emergence of the first functional nucleic-acid–peptide assemblies, which further developed into biological assemblies such as the ribosomes and viruses.
Properties of the P
c(4312) pentaquark and its bottom partner
Authors: Azizi K. , Sarac Y. , Sundu H. 
Published: February 2021

Abstract
We present an analysis of the newly observed pentaquark

to shed light on its quantum numbers. To do that, the QCD sum rules approach is used. The measured mass of this particle is close to the

threshold and has a small width, which supports the possibility of its being a molecular state. We consider an interpolating current in a molecular form and analyze both the positive and negative parity states with spin-

. We also consider the bottom counterpart of the state with similar molecular form. Our mass result for the charm pentaquark state supports that the quantum numbers of the observed state are consistent with

.
Estimation of dynamically changing navigation parameters of the group of autonomous vehicles
Authors: Korolev L Y 
Published: February 2021

Abstract
The estimates of natural and mutual coordinates and speeds of movement of autonomous vehicles moving the structure have been integrated. Cases of application of navigation systems of different accuracy for an arbitrary number of sets in a group are considered. There are given expressions for covariance matrices of integration errors in two ways. The first method is formulated based on a Kalman vector filter. The second algorithm consists of a two-step evaluation procedure involving a static evaluation and a Kalman filter. Results of comparative analysis of efficiency of the considered methods are presented.
Eigenvalues and eigenvectors of Ising model on hypercube
Authors: Kryzhanovsky B , Litinskii L 
Published: February 2021

Abstract
For a multidimensional Ising model, we expressed eigenvalues of the connection matrix in terms of the spin-spin interaction constants and trigonometric polynomials. In such systems, the eigenvectors are the Kronecker products of the well-known eigenvectors for the one-dimensional case. When boundary conditions are periodic, it is possible to obtain rigorous expressions for the eigenvalues when there is an arbitrary long-range interaction in the system.
Mathematical model of the interaction of a torch discharge with film elements
Authors: Novomeysky D N , Piganov M N 
Published: February 2021

Abstract
The process of interaction of a flare discharge with a resistive film is described. The thermal balance equation is considered. Taking into account the exponential dependence of electrical conductivity on temperature a mathematical model of the interaction of a flare discharge with a resistive film is constructed based on this equation. Increasing the mathematical model accuracy for this interaction is considered.
Methods for determining the location parameters of GTE blade profiles based on their measurement results
Authors: Bolotov M A , Pechenin V A , Ruzanov N V , Grachev I A 
Published: February 2021

Abstract
The location parameters of the actual profile of the blades of a gas turbine engine relative to its nominal position are used to assess the quality of these parts manufacture. The complex shape of the aerodynamic surfaces of the blades, as well as the errors in their manufacture make it difficult to unambiguously determine the displacement and rotation of the actual profile. The use of various methods for calculating the parameters under consideration may result in mismatching values, which raises the question of a reasonable choice of the methods used. This paper presents two methods for determining the geometric parameters of the location of the aerodynamic profiles of the blades, taking into account the features of their manufacture and the requirements of the existing industry standard. Also, the work evaluated the effectiveness of the proposed methods in determining the processing parameters of the blades of a gas turbine engine.
Modeling of physical processes of interaction of ultrasonic wave with metal structures for detection of defects
Authors: Mozhayko A A , Manninen S A , Davydov V V , Yu Rud V 
Published: February 2021

Abstract
In the article the features of the physical processes modeling of the ultrasonic wave interaction to the metal structures are considered. The mathematical model for calculating the acoustic field of a single element of a 32-element electromagnetic acoustic phased array of SV-waves is developed. The computer simulation of the process of reflection of the ultrasonic beam from a defect is carried out. The developed model allows to study the influence of the shape, size, location of defects in the plate, as well as the geometric parameters of the plate, on the formation of the reflected signal.
Mathematical modeling of spectra of nuclear magnetic resonance signals for investigation of condensed media in express mode
Authors: Makeev S S , Kuptsov V D , Davydov V V , Dudkin V I , Yu Rud V 
Published: February 2021

Abstract
In article the necessity of developing a mathematical model for converting the recorded NMR signal using a modulation technique into the spectrum for new investigations is substantiated. The comparison of various methods for describing the shape of the registration NMR signals to determine the line structure and various practical tasks solve is performed. A mathematical model for to represent the NMR signal in the form of a spectrum, taking into account the features of its registration from condensed matter is developed. Spectra of calculated and experimental NMR signals are presented. Its comparison is carried out.
Mathematical model of the distribution of electrical and thermal energy in the working element of an information and measurement system designed to study the process of initiating industrial explosives
Authors: Krivchenko E S , Nechaev A S , Moshchenskij Y V , Bogacheva O A 
Published: February 2021

Abstract
The use of sensitive explosives to detonate the main charge during perforation of solid rock layers, demolition of high-rise and strong structures, etc. is an inconvenient and dangerous method of initiation. This makes it urgent to develop and implement alternative methods for detonating explosives. One of these methods is to transmit a thermal pulse of the required power using thermal conductivity from a metal rod to an explosive. The determination of the thermal power of the pulse required for the occurrence of detonation is carried out by indirect measurements. The rating allocated by standard heat rod method is pretty rude, does not account for losses at the points of contact and spatial distribution of heat in the core, depending on the electric pulse parameters. In this paper, mathematical models of the formation of a thermal field in the rod, taking into account these factors, are constructed. Based on the results of the obtained models, numerical calculations are made for rods of different sizes and signals of different shapes and power. The results of the work allow us to determine the necessary initial and boundary conditions for a further description of fast-flowing thermal processes.
Comparison of methods for baseline determining of fluorescent detector signals of genetic analyzer
Authors: Batov Y V , Puzko D A , Petrov A I , Davydov V V , Yu Rud V 
Published: February 2021

Abstract
In article of the methods for baseline determining of signals from a fluorescent detector of a genetic analyzer are discussed. The simulated for signal which has characteristics identical to the characteristics of a real signal is performed. The comparison of the methods to the criterion of mean square error and calculation speed for model signals is done. A qualitative analysis of the effectiveness of methods on real signals is carried out. The theoretical calculations by these methods and research results are presented.
Investigation of 3D ultra-wideband bandpass filter model based on microstrip multimode resonators
Authors: Belyaev B A , Khodenkov S A , Shepeta N A , Popov A M 
Published: February 2021

Abstract
Here are the results of theoretical studies of microstrip multimode resonators with a short-circuited section of a strip conductor and ultra-wideband filter based on five-mode resonators. Electrical characteristics of microwave devices were obtained by means of numerical electrodynamic analysis of their 3D models. Substrates with dielectric constant of ε = 80 and ε = 9.8 were used in calculations. A synthesized filter with a 100% bandwidth has high frequency-selective properties and can be used in radio equipment of tropospheric and space communication with the advanced information transfer.
Research of optimality of the nanosatellite nominal reorientation trajectory
Authors: Chekashov A S , Kramlikh A V 
Published: February 2021

Abstract
Nanosatellites have serious limitations on the onboard energy. Therefore, it is necessary to find a method of constructing a nominal reorientation trajectory that will optimally use the resources available onboard. In this paper the process of constructing of a nominal reorientation trajectory in the plane of nanosatellite orbit is considered. The problem of constructing a nominal reorientation trajectory was solved using the inverse dynamic problem method and Pontryagin maximum principle. A comparison of the results obtained using these two methods was made. As a result, it was noted that the solution obtained by the inverse dynamic problem method is close to the solution obtained using the Pontryagin maximum principle. This allows us to speak about the optimality of the inverse dynamics problem method.
Investigation of the potential characteristics of a satellite multi-beam hybrid-mirror antenna by modeling the process of adaptation to random deformations of the reflector
Authors: Mochalov V V , Choni Yu I , Romanov A G , Yu Danilov I 
Published: February 2021

Abstract
The stabilization of the beams of large-sized multi-beam hybrid mirror antenna (MBHMA), the reflector profile of which is subject to distortion due to changing operational factors, is a complicated technical task. One of the ways to maintain energy efficiency of the satellite communications system in these circumstances is to adapt the amplitude-phase distribution of the clusters of the antenna array to random deformations of the reflector. By statistical modeling, the potentially achievable characteristics of the system are evaluated. Three variants of adaptation of cluster excitation were modeled: a) for fixed clusters, b) for adaptation of excitation, c) for adaptation of weights and position of clusters, d) for adaptation of weights and cluster configurations. For multivariate calculations, we use the simplified model of MBHMA that we have proposed. Comparison with calculations in Ticra Grasp environment confirmed the correctness of the model. Not only radiation patterns, but also focal spots on the antenna array we calculated to determine the rational composition of cluster elements and the vector of their excitation coefficients. Beams gain within the service area for reflector deformations were the subject of analysis. The studies showed that gain decrease can be reduced to 0.1 … 0.2 dB instead of 1.6 dB taking place without adaptation.
Modelling of machining center vibration stability by the D-partitions method
Authors: Krol O S , Sokolov V I , Tsankov P , Logunov O M 
Published: February 2021

Abstract
The stability of operation, vibration-free processing of products various types at high-speed machining centers suggests the improvement of research in the field of the dynamics of machine tools and their main forming units. The three-dimensional models of the forming spindle node and the corner table of the machining center for the drilling-milling-boring type in the CAD environment KOMPAS-3D have been developed. An algorithm for analyzing the dynamic quality of the machine elastic parts based on the constructed static and frequency formular in the mathematical environment MAPLE is proposed. Programs have been developed and graphs of the main frequency characteristics and the hodograph of the transfer function for the spindle node in the specialized Signal Processing module have been obtained. The method of D-partitions using to estimate the vibration stability of the forming units on an example of 4 coordinate milling machining centers is introduced. Experiments on two variants of technological adjustments with different dimensions of the tool block (the cantilever part of the spindle assembly) were carried out. The analysis of stability in the plane of the cutting process optimized parameter (specific cutting force) was carried out. The region and the boundary of the stable functioning of the machine and, on this basis, the optimum modes of machining by the criterion of vibration stability are revealed.
The use of an algorithm for determining the thrust of an electric propulsion system during a flight into a geostationary orbit
Authors: Salmin V V , Chetverikov A S 
Published: February 2021

Abstract
The article deals with the problem of control during the flight to the geostationary orbit of interorbital transport vehicles with low-thrust electric propulsion systems. The analysis of the influence on the final trajectory parameters of disturbing factors of various kinds, including the presence of a systematic error in the implementation of electric propulsion thrust. An algorithm for narrowing the area of deviation of the final trajectory parameters during the flight to geostationary orbit using low-thrust engines has been developed, which includes an algorithm for forming nominal programs for controlling the thrust vector and an algorithm for refining the amount of thrust created by an electric propulsion system, based on measurements of the actual period of circulation.
Determination initial approximations in solving the problem of numerical optimization of a large-sized space structure using linear extrapolation of optimal solutions
Authors: Salmin V V , Peresypkin K V , Chetverikov A S , Tkachenko I S 
Published: February 2021

Abstract
The parameters of a large-sized space structure are determined using numerical optimization using the gradient method. The complexity of the boundary of the constraints makes the optimal solution poorly conditioned relative to the initial point of the iterative process. The initial point is selected based on the optimal solutions found with an incomplete set of design variables. The initial point is found by linear extrapolation of these optimal solutions. In the problem under consideration, this approach made it possible to obtain a better locally optimal solution than was possible with the help of an intuitive choice of the starting point.
Development of novel mathematical models of plate heat exchanger for the task of optimization main parameters of the aviation gas turbine engine with heat recovery
Authors: Omar H H , Kuz’michev V S , Tkachenko A Y , Thomas Jayachandran A V 
Published: February 2021

Abstract
Nowadays, the task of increasing the economic and technical efficiency of the gas turbine engine and decrement of the specific weight and specific fuel consumption is one of the main targets in the development of the aviation gas turbine engine. A promising approach for decrement of specific fuel consumption and obtaining high thermal efficiency of the gas turbine engine (30% and above) is based on the concept of the recuperative cycle of the gas turbine engine. The article presents the computer-aided calculation for analysing the heat exchanger surface and developing novel mathematical models of heat exchanger in terms of weight goodness, flow passage goodness, and optimum weight and flow passage, furthermore, the study presents the novel mathematical models of the pressure drops in the air and gas channels of the heat exchanger. 18 different heat transfer surfaces for heat exchanger cores have been evaluated and the results are presented. The same hydraulic diameter assumed for all heat transfer surfaces and only their thermo-hydraulic performances evaluated during the calculation design. To assess the reliability of the obtained models, the results of the design calculations of the developed models compared with the data of other authors and with the data of the existing gas turbine engine with heat exchanger. The obtained models focus on mathematical design calculation for optimizing the main thermodynamic parameters of a gas turbine engine coupled with a heat exchanger at the stage of conceptual design of aviation gas turbine engine with heat recovery of exhaust gas.
The digital photoelasticity method and finite element analysis for determination of the multi-point crack-tip field series expansions for notched semi-disks
Authors: Stepanova L V , Belova O N 
Published: February 2021

Abstract
The digital photoelastic method for the construction of the multi-point crack-tip series expansions in isotropic elastic semi-disks is employed. The series of cracked specimens in the form of the semi-disk with vertical and inclined notches from optically active materials (polycarbonates) were produced and tested under three-point bending. The principal intent of this experimental procedure of the phototelasticity technique was estimation of the amplitude coefficients in the Williams expansion in which the non-singular high-order terms are taken into account. The first ten coefficients in the multi-point series expansion have been ascertained. To retrieve the points belonging to the isochromatic fringe patterns and having the minimum light intensity the digital image processing scheme was utilized. The scheme of the over-deterministic method for evaluation of the amplitude coefficients (fracture mechanics parameters) is applied. Additionally, the problem was reduced to the problem of minimizing the objective function which is the quadratic form for the stress field in terms of unknown fracture mechanics parameters. The finite element analysis for the same series of the notched specimens was performed. The demeanour of the stress field in the neighbourhood of the notch tip for different types of mixed mode loading was elucidated from finite element analysis. The coefficients of the asymptotic presentation of the stress and displacement fields are recovered from finite element results. It is shown that the multi-point coefficients are in good agreement with experimental observations.
Mathematical modeling of phytoplankton populations evolution in the Azov Sea
Authors: Belova Y V , Chistyakov A E , Leontyev A L , Filina A A , Nikitina A V 
Published: February 2021

Abstract
The paper describes the construction of a three-dimensional mathematical model of biogeochemical processes, considering the salinity and temperature influence on the phytoplankton populations development. The paper proposes a new difference scheme for solving convection-diffusion-reaction problems at large values of the Peclet grid number (2<Pe≤20), which is a linear combination of the central and the upwind leapfrog difference schemes. The three-layer difference scheme is more accurate than the traditional upwind leapfrog difference scheme for problems where convection prevails over diffusion. The construction of discrete equations for solving the problem of biogeochemical cycles on the basis of the scheme considering the filling of cells is described. The stationary regimes of phytoplankton dynamics problem were researched considering the transformation of phosphorus, nitrogen and silicon forms. Results of software complex, which allows to simulate biogeochemical processes in the Azov Sea, were described. The software package allows to forecast the dynamics of the Azov Sea ecosystem development in the conditions of modern salinization.