Values Of Radius Research Articles

Оптическая система для малогабаритного космического аппарата дистанционного зондирования Земли формата CubeSat

The paper considers relevance of creating the small-sized high-resolution optical systems for the small spacecraft. It describes the current state of domestic and foreign systems engaged in the Earth remote sensing of the CubeSat format that confirmed the need to develop domestic multi-component satellite constellations. Unlike the large-sized spacecraft, the CubeSat standard implies introduction of the micro-format satellites. In order to reduce overall dimensions of the system and minimize the chromatic aberrations effect on the image quality in selecting the optical scheme components, mirrors are preferred, as a rule. Among all possible design schemes, the Ritchey --- Chretien optical scheme is the most promising due to its simplicity, small overall dimensions and high optical performance in a wide spectral range for the CubeSat satellites. Main optical and technical parameters, as well as the optical system characteristics for a small spacecraft are provided. For typical systems, the paper proposes a calculation technique; and a simulation model was created making it possible to assess the optical system image quality. The root-mean-square value of the point scatter spot radius in the image plane was taken as the criterion in evaluating the image quality. It is shown that the Ritchey --- Chretien optical scheme and its elements are characterized by its relative easiness in implementation due to using the studied technologies of the lens and mirror elements manufacture and ensuring high image quality and required overall dimensions, which makes it possible to use them in creating a multi-component satellite constellation

Stratospheric aerosol size reduction after volcanic eruptions

Abstract. The stratospheric aerosol layer plays an important role in the radiative balance of Earth primarily through scattering of solar radiation. The magnitude of this effect depends critically on the size distribution of the aerosol. The aerosol layer is in large part fed by volcanic eruptions strong enough to inject gaseous sulfur species into the stratosphere. The evolution of the stratospheric aerosol size after volcanic eruptions is currently one of the biggest uncertainties in stratospheric aerosol science. We retrieved aerosol particle size information from satellite solar occultation measurements from the Stratospheric Aerosol and Gas Experiment III mounted on the International Space Station (SAGE III/ISS) using a robust spectral method. We show that, surprisingly, some volcanic eruptions can lead to a decrease in average aerosol size, like the 2018 Ambae and the 2021 La Soufrière eruptions. In 2019 an intriguing contrast is observed, where the Raikoke eruption (48∘ N, 153∘ E) in 2019 led to the more expected stratospheric aerosol size increase, while the Ulawun eruptions (5∘ S, 151∘ E), which followed shortly after, again resulted in a reduction in the values of the median radius and absolute distribution width in the lowermost stratosphere. In addition, the Raikoke and Ulawun eruptions were simulated with the aerosol climate model MAECHAM5-HAM. In these model runs, the evolution of the extinction coefficient as well as of the effective radius could be reproduced well for the first 3 months of volcanic activity. However, the long lifetime of the very small aerosol sizes of many months observed in the satellite retrieval data could not be reproduced.

Evaluation of direct beam energy received by convex solar collectors and their optimal orientations

We use analytical and numerical methods to evaluate the daily beam energy received by some convex surfaces. Spherical, hemispherical, cylindrical, and semi-cylindrical convex surfaces with arbitrary tilt angles have been investigated and compared with a flat surface of unit area. Diffusive irradiations (sky and ground) were not considered. For hemispherical and semi-cylindrical surfaces, the optimal orientations at which the received beam energy is maximal were obtained for each day of the year. The dependence of the optimal tilt angle on the day of the year is qualitatively the same as for the flat surface. Clear sky condition has been assumed to hold in this work. It is shown that a flat surface per unit of its area receives highest beam energy among other convex surfaces whereas a sphere receives the least amount. Furthermore, the received daily beam energy per unit of the ground-occupied area has been calculated. In this case, a cylindrical surface with a range of values of radius to height ratio receives the highest amount of energy whereas a flat surface receives the least. This aspect becomes noticeable in places where there are some limits, e.g., land price or any other limitation on the available surface area.

Modeling and Optimization of Surface Integrity and Sliding Wear Resistance of Diamond-Burnished Holes in Austenitic Stainless Steel Cylinder Lines

This article outlines a technology for hole-finishing in short-length cylinder lines to improve wear resistance. The technology is based on an optimized diamond-burnishing (DB) process. The latter was implemented on conventional and CNC lathes, milling machines, and machining centers using a simple burnishing device with an elastic beam. The material used in this study was AISI 321 austenitic stainless steel. The governing factors used were the radius of the diamond insert, burnishing force and feed rate. The objective functions relating to surface integrity characteristics were selected on the basis of their functional importance relative to the wear resistance of the processed hole surface: height and shape roughness parameters, surface microhardness, and surface residual axial and hoop stresses. The one-factor-at-a-time method (used to reduce the factor space), a planned experiment, and regression analyses were used. The multi-objective optimization tasks, which were defined for three diamond insert radius values of 2, 3, and 4 mm, were solved via the Pareto-optimal solutions approach available for a non-dominated sorting genetic algorithm (NSGA-II). Using the optimal values of the governing factors selected from the Pareto fronts, cylinder lines were processed. Samples were then cut from these cylinder lines for reciprocating sliding wear tests under two modes: dry friction and boundary lubrication friction. Additionally, wear test samples were cut from the cylinder line, which was finished with traditional grinding. A finite element simulation was then used to select an appropriate pressing force. The results obtained from the reciprocating sliding wear tests under both the dry and boundary lubrication friction regimes show that to minimize the wear on cylinder lines made of AISI 321 steel, DB with a diamond insert of radius 2 mm is the optimal finishing process.

Biosynthesis of Ag@Au bimetallic nanoparticles from Hymenaea courbaril extract (Jatobá) and nonlinear optics properties

Green synthesis of metal nanoparticles (NPMs) has been considered an innovative and sustainable alternative to produce metallic nanoparticles, due to the use of biological structures or parts thereof as reducing and stabilizing agents. This study reports, for the first time, the use of leaf extract from Hymenaea courbaril (Jatobá) as a reducing and stabilizing agent in the synthesis of bimetallic nanoparticles (Ag@AuNPs) in different proportions. Also, the nonlinear optical properties were investigated with continuous laser excitation at 532 nm by Thermal lens spectroscopy and Z-scan technique. The leaf extract is composed of chemical groups such as tannins, flavonoids, and others, confirmed by infrared spectroscopy, responsible for the process of chemical reduction. The UV–VIS spectra confirmed the formation of nanoparticles, through the presence of typical Surface Plasmon Resonance (SPR) bands characteristic of these nanostructures, ranging from 433 nm to 508 nm, depending on the proportion of silver and gold precursors. The nanostructures have an average hydrodynamic radius value of 48 nm and all exhibit a negative surface charge. TEM analysis shows that the Ag@AuNPs were spherical-like shape. The thermo-optical properties were investigated using thermal lens spectroscopy and showed thermal diffusivity values in the range of (8–10) × 10−4 cm2/s, depending on the SPR position. The Z-scan technique shows that the nonlinear refractive index is negative, and we observe the reverse saturable absorption. The results obtained indicate that these nanostructures have potential for nonlinear optics and photothermal applications.

Kepler Light Curve Modeling of KIC 9788457

Eclipsing binary systems are significant objects for astrophysical studies since they offer more accurate fundamental stellar parameters (mass, radius). Therefore, in this study, the first binary modeling of KIC 9788457 is presented to estimated the fundamental stellar parameters of the system. The photometric data of the system were taken from Kepler that provides high-quality data. When the light curve was checked it was found that the more luminous massive component has a significant light contribution into total. Therefore, using the spectral energy distribution and also B-V values Teff value was estimated for the primary component. Utilizing this Teff value, the binary modeling of the system was carried out. As a result, fundamental physical parameters of KIC9788457 were obtained. The radius (R) and mass (M) values of the components are M1=1.89 ± 0.05 Msun and R1= 2.03 ± 0.02 Rsun for the massive component and M2=0.81 ± 0.02 Msun and R2= 1.74 ± 0.03 Rsun for the less massive component, respectively. Additionally, the distance of the system was determined to be 1407 ± 85 pc.

Single and two-cells shape analysis from energy functionals for three-dimensional vertex models.

Vertex models have been extensively used for simulating the evolution of multicellular systems, and have given rise to important global properties concerning their macroscopic rheology or jamming transitions. These models are based on the definition of an energy functional, which fully determines the cellular response and conclusions. While two-dimensional vertex models have been widely employed, three-dimensional models are far more scarce, mainly due to the large amount of configurations that they may adopt and the complex geometrical transitions they undergo. We here investigate the shape of single and two-cells configurations as a function of the energy terms, and we study the dependence of the final shape on the model parameters: namely the exponent of the term penalising cell-cell adhesion and surface contractility. In single cell analysis, we deduce analytically the radius and limit values of the contractility for linear and quadratic surface energy terms, in 2D and 3D. In two-cells systems, symmetrical and asymmetrical, we deduce the evolution of the aspect ratio and the relative radius. While in functionals with linear surface terms yield the same aspect ratio in 2D and 3D, the configurations when using quadratic surface terms are distinct. We relate our results with well-known solutions from capillarity theory, and verify our analytical findings with a three-dimensional vertex model.

Model-independent traversable wormholes from baryon acoustic oscillations

In this paper, we investigate the model-independent traversable wormholes from baryon acoustic oscillations. Firstly, we place the statistical constraints on the average dark energy equation of state ωav by only using BAO data. Subsequently, two specific wormhole solutions are obtained, i.e, the cases of the constant redshift function and a special choice for the shape function. For the first case, we analyze the traversabilities of the wormhole configuration, and for the second case, we find that one can construct theoretically a traversable wormhole with infinitesimal amounts of average null energy condition violating phantom fluid. Furthermore, we perform the stability analysis for the first case, and find that the stable equilibrium configurations may increase for increasing values of the throat radius of the wormhole in the cases of a positive and a negative surface energy density. It is worth noting that the obtained wormhole solutions are static and spherically symmetrical metric, and that we assume ωav to be a constant between different redshifts when placing constraints, hence, these wormhole solutions can be interpreted as stable and static phantom wormholes configurations at some certain redshift which lies in the range [0.32, 2.34].

Technical variability of cornea parameters derived from anterior segment OCT fitted with Fringe Zernike polynomials.

This study uses bootstrapping to evaluate the technical variability (in terms of model parameter variation) of Zernike corneal surface fit parameters based on Casia2 biometric data. Using a dataset containing N = 6953 Casia2 biometric measurements from a cataractous population, a Fringe Zernike polynomial surface of radial degree 10 (36 components) was fitted to the height data. The fit error (height - reconstruction) was bootstrapped 100 times after normalisation. After reversal of normalisation, the bootstrapped fit errors were added to the reconstructed height, and characteristic surface parameters (flat/steep axis, radii, and asphericities in both axes) extracted. The median parameters refer to a robust surface representation for later estimates of elevation, whereas the SD of the 100 bootstraps refers to the variability of the surface fit. Bootstrapping gave median radius and asphericity values of 7.74/7.68 mm and -0.20/-0.24 for the corneal front surface in the flat/steep meridian and 6.52/6.37 mm and -0.22/-0.31 for the corneal back surface. The respective SD values for the 100 bootstraps were 0.0032/0.0028 mm and 0.0093/0.0082 for the front and 0.0126/0.0115 mm and 0.0366/0.0312 for the back surface. The uncertainties for the back surface are systematically larger as compared to the uncertainties of the front surface. As measured with the Casia2 tomographer, the fit parameters for the corneal back surface exhibit a larger degree of variability compared with those for the front surface. Further studies are needed to show whether these uncertainties are representative for the situation where actual repeat measurements are possible.

Thermodynamics of non-linear magnetic-charged AdS black hole surrounded by quintessence, in the background of perfect fluid dark matter

In this paper, we study the thermodynamic features of a non-linear magnetic-charged AdS black hole surrounded by quintessence, in the background of perfect fluid dark matter(PFDM). After having constructed the corresponding metric, we analyse the structure of the horizon. We find that the existence of inner or outer horizon are constrained by the presence of dark matter. Afterwards, we put out the mass and the temperature of the black hole, in order to get its entropy. Subsequently, we find the expression of the pressure which leads us to get the table of critical values and the isothermal diagram. Especially, we find that the critical values of the temperature and the pressure increase as the dark matter parameter increases. Also, analysing the isothermal diagram, we observe a van der Waals-like behaviour remarked by the presence of a first-order phase transition when we cross the critical temperature. Additionally, we compute and plot the heat capacity and the Hessian matrix of the black hole mass. For the heat capacity, we find that a second-order phase transition occurs, leading the black hole to move from stable phase to unstable one. Furthermore, it comes out that this phase transition point is shifted towards higher values of the horizon radius, as we decrease the dark matter density and increase the quintessence density.

Numerical Modelling Strategies for Column Rocking Behavior in Traditional Timber Structures

ABSTRACT As a typical feature of traditional Chinese timber structures, columns with floating foot joints are prone to rocking under horizontal force. The column rocking behavior plays an important role in resisting lateral loads. This paper proposes modelling strategies for the rocking behavior of traditional timber columns. The proposed model can capture the contact state of the column foot via a series of distributed axial springs and the possible sliding via a horizontal spring. It has a lower computational cost than refined finite element (FE) models and is independent of numerical calibration compared to rotational spring models. The modelling strategies were validated against refined FE models and experimental data available in the literature. The principle behavior of the approach was carefully investigated including contact stiffness, distribution modes, spring numbers, column bending effects, and computational efficiency. Results show that the effective compression height of the column foot can take the value of the column radius to determine spring stiffness. Column bending needs to be considered in the mechanical analysis of column foot joints for slender columns. The case study on the lateral stiffness of traditional timber frames confirms the applicability of the proposed model in the structural analysis of ancient timber buildings.

Sensitivity of Mass Distribution with Respect to Pitch Motions of High-Speed Craft

Beside of environmental conditions, ship characteristics also greatly affect in ship behavior when operating at sea, called seakeeping ability. The shape of the hull, appendages, damping, and the weight distribution of ship are some of the factors that determine how the ship motion response occurred. This paper examines how much the pitch motion is influenced in high-speed craft due to the changing of the gyration radius. By using the strip theory method, and by taking the irregular head sea condition and a wave height of 4 meters, then the ship speed and the wave period are varied to determine the pitch motion amplitude at 3 values ​​of gyration radius: 0.2, 0.25 and 0.3 of the ship's length. The results of the study show that at higher ship speeds, the gyration radii greatly influence the pitch amplitude. As for changes in the wave period, the influence is significant at value of 5 second. From these two results, it is clear that the ship's gyration radii must be determined precisely to be able to predict an accurate pitch motion response on a high-speed craft.

Failure criterion for brittle materials with U‐notches: Unification of characteristic length‐based and grain size‐based criteria

AbstractHere, the limitations of characteristic length‐based (Lchb) and grain size‐based (Gb) criteria with two or three parameters were pointed out employing the apparent toughness tests of 12 different ceramics at a large span range of U‐notch root radius (ρ) values. After comprehensively considering the potential influencing factors of stress intensity factor (Kc), ρ divided by critical notch tip radius (ρc) was proposed as the independent variable, and the data of 21 materials (covering ceramics, plastics, resins, rocks, and metals) was summarized and discussed to establish a simple and more applicable Kc prediction model. Results indicated that Kc/KIc was a power function of ρ/ρc with a power exponent n of 0.5 for ideal materials and less than 0.5 for actual materials. It was also found that ρc can be calculated simply by KIc2/(πσ02), where σ0 represented the inherent strength. This semiempirical criterion succeeded in unifying the Lchb and Gb criteria without introducing more parameters to increase the prediction accuracy of the Kc at the U‐notch root for brittle materials like ceramics.

Quasiperiodic oscillations around hairy black holes in Horndeski gravity

Testing gravity theories and their parameters using observations is an important issue in relativistic astrophysics. In this context, we investigate the motion of test particles and their harmonic oscillations in the spacetime of non-rotating hairy black holes (BHs) in Hordeski gravity, together with astrophysical applications of quasiperiodic oscillations (QPOs). We show possible values of upper and lower frequencies of twin-peak QPOs which may occur in the orbits from innermost stable circular orbits to infinity for various values of the Horndeski parameter q in relativistic precession, warped disk models, and three different sub-models of the epicyclic resonant model. We also study the behaviour of the QPO orbits and their position relative to innermost stable circular orbits (ISCOs) with respect to different values of the parameter q. It is obtained that at a critical value of the Horndeski parameter ISCO radius takes 6M which has been in the pure Schwarzschild case. Finally, we obtain mass constraints of the central BH of microquasars GRS 1915+105 and XTE 1550-564 at the GR limit and the possible value of the Horndeski parameter in the frame of the above-mentioned QPO models. The analysis of orbits of twin peak QPOs with the ratio of upper and lower frequencies 3:2, around the BHs in the frame of relativistic precession (RP) and epicyclic resonance (ER4) QPO models have shown that the orbits locate close to the ISCO. It is obtained that the distance between QPO orbits and ISCO is less than the error of the observations.

Central hole radius optimization of fuel pellet in WWER–1000 using artificial bee colony and genetic optimization algorithms

The central hole of fuel pellets was traditionally proposed to improve the fuel performance in WWER-1000 reactors. One way to achieve higher fuel consumption is to increase the heat transfer and optimize the average temperature of the fuel, provided that the pressure on the cladding remains within the standard range. Contrary to conventional design methods, we propose a methodology to find the optimum value of the central hole radius using FRAPCON3.1 equipped with Genetic algorithm (GA) and Artificial Bee Colony (ABC). Two optimization methods have been chosen to check the effect of the variation of the optimization method on the final result. The optimization algorithms execute FRAPCON3.1 for different sizes of the fuel pellet central hole, and a defined fitness function is evaluated for each suggested radius. The outcome proves efficient for different working regimes of the reactor. A sample test–case is invoked at the end proving the superiority of the optimized radius found through our approach over the initial Russian vendor's. Results reveal that while the average pellet temperature has decreased, the cycle length has become longer, both achievements under safety criteria.

Simulation of turning traffic at a controlled inter-section

Problem. Optimizing the parameters of traffic light regulation can reduce delays and queues of vehicles, increase the throughput of intersections, and thus increase the quality of the functioning of the city's transport network. This question is especially relevant for Ukraine, because in these conditions it is impossible to carry out a significant modernization of the city's transport network, but within the framework of the post-war reconstruction of the city, it is possible to carry out the improvement of the geometric parameters of the intersection. However, among all the factors that affect the throughput of a regulated intersection, in the scientific literature and normative documents, insufficient attention is paid to the geometrical parameters of the intersection itself. Goal. The geometric parameters of the intersection first of all affect the characteristics of the movement of the selected rotating streams, and through this - the saturation of the stream. Therefore, it is of interest to simulate the movement of turning traffic at an intersection and compare the results with empirical models. Methodology. To estimate the permeability of the selected turning lanes, the correction of the ideal saturation flow is most often used with coefficients, the values ​​of which are either calculated depending on the geometric parameters of the intersection (for example, F. Webster's methodology), or are taken as constant (Posіbnik НСМ 2000). The flow saturation value for the selected turning lane was also calculated taking into account the minimum safe distance of the vehicles in the traffic flow. It is shown that these methods give different values ​​of flow saturation. Results. To check the degree of influence of the rotary flow traffic radius on the flow saturation of the selected traffic, simulation modeling of the robot of the conditional adjustable intersection was carried out in the program PTV VISSIM. The parameters of the model were chosen in such a way that a sufficiently long queue was released before the stop line. In the process of imitation, after turning on the green signal, the virtual detector fixed the number of cars that passed through the dedicated right-turn lane. Practical value. The results showed that for selected turning lanes, the saturation flow increases with an increase in the radius of the turning flow trajectory, which corresponds to the classical formula of F. Webster, when the radius value is up to 15 m. Therefore, adjusting the saturation flow for selected turning flows is appropriate this time. When the flow moves along a path with a larger radius, the saturation flow does not depend on the geometry of the intersection.

Quantum dust cores of black holes

We describe the ground state for a gravitationally collapsed ball of dust as the direct product of wavefunctions for dust particles distributed over an arbitrary number of nested layers. This allows us to estimate the expectation value of the global radius as well as the effective energy density and pressures for the dust core of quantum black holes. In particular, the size of the quantum core does not depend on the number of layers and the mass function is shown to grow linearly with the areal radius up to the outermost layer.

Application of nanotechnology in breast cancer screening under obstetrics and gynecology through the use of CNN and ANFIS

Breast cancer is the leading reason of death among women aged 35 to 54. Breast cancer diagnosis still presents significant challenges, and preventing the disease's most severe symptoms requires early detection. The role of nanotechnology in the tumor-treatment has recently attracted a lot of interest. In cancer therapies, nanotechnology plays a major role in the medication distribution process. Nanoparticles have the ability to target tumors. Nanoparticles are favorable and maybe preferable for usage in tumor detection and imaging due to their incredibly small size. Quantum dots, semiconductor crystals with increased labeling and imaging capabilities for cancer cells, are one of the particles that have received the most research attention. The design of the research is cross-sectional and descriptive. From April through September of 2020, data were gathered at the State Hospital. All pregnant women who came to the hospital throughout the first and second trimesters of the research's data collection were included in the study population. 100 pregnant women between the ages of 20 and 40 who had not yet had a mammogram comprised the research sample. 1100 digitized mammography images are included in the dataset, which was obtained from a hospital. Convolutional neural networks (CNN) were used to scan all images, and breast masses and mass comparisons were made using the malignant-benign categorization. The adaptive neuro-fuzzy inference system (ANFIS) then examined all of the data obtained by CNN in order to identify breast cancer early using inputs based on the nine different inputs. The precision of the mechanism used in this technique to determine the ideal radius value is significantly impacted by the radius value. Nine variables that define breast cancer indicators were utilized as inputs to the ANFIS classifier, which was then used to identify breast cancer. The parameters were given the necessary fuzzy functions, and the combined dataset was applied to train the method. Testing was initially performed by 30% of dataset that was later done with the real data obtained from the hospital. The accuracy of the results for 30% data was 84% (specificity =72.7%, sensitivity =86.7%) and the results for the real data was 89.8% (sensitivity =82.3%, specificity =75.9%), respectively.

Intrusion Monitoring Based on High Dimensional Random Matrix by Using Ultra-Weak Fiber Bragg Grating Array

In order to ensure that a perimeter security system can work effectively, a convenient and effective event detection algorithm has an important engineering significance. Given the above background, in this paper, we propose a high reliability intrusion event recognition method and vibration sensing system, based on ultra-weak fiber Bragg grating array, by using high dimensional random matrix. We obtain a high sensitivity optical interference signal by constructing a patch-matched optical interference system, then compose the demodulated interference signal into a high-dimensional random matrix. The statistical characteristics of the matrix for the Marcenko-Pastur (M-P) law and ring law are used to confirm the presence of intrusion events efficiently, which can reflect the limit spectrum distribution of the high-dimensional random matrix; meanwhile, the abnormal state quantity and moment are obtained. Further, the average spectral radius value is used to judge the fault cause. Field experimental results show that the proposed method can effectively obtain the correct monitoring data for the sensor array. By comparing the monitoring results of normal operation and crusher operation, we can detect the intrusion event in 4.5 s, and the accuracy rate can reach more than 90%, which verifies that the proposed high-dimensional random matrix analysis method can work properly, proving a practical engineering application prospect.

Pre-filter analysis for retrieval of microphysical particle parameters: a quality-assurance method applied to 3 backscatter (β) +2 extinction (α) optical data taken with HSRL/Raman lidar.

We analyze the solution space of 3β+2α optical data inferred from lidar measurements, i.e., backscatter coefficients at three wavelengths and extinction coefficients at two wavelengths. These optical data are governed by microphysical parameters that can be expressed in terms of particle size distribution, effective radius, and complex refractive index (CRI). In our analysis, we consider two scenarios of the solution space. First, it can be expressed in terms of monomodal particle size distributions represented either by fine modes or by coarse modes. Secondly, the particle size distributions contain a fine mode as well as a coarse mode. Consideration of both scenarios and different values of the effective radius and CRI allows us to find synthetic 3β+2α optical data and corresponding intensive parameters (IPs) such as lidar ratios, backscatter- and extinction-related Ångström exponents at the available measurement wavelengths. Based on interdependencies between synthetic IPs and various microphysical properties, the qualitative and quantitative criteria for the optical data quality-assurance tool are developed. We derive the conditions of smoothness, closeness, convergence, and stability of the solution space for the quantitative criteria to test the quality of the 3β+2α optical data. Our novel methodology, to the best of our knowledge, can be used not only for particles of spherical shape, but also for cases in which particles are irregularly shaped. Another strength of our methodology is that it also works for the case of a size-dependent and wavelength-dependent CRI. We show the potential of this methodology for a measurement case from the ORACLES campaign. Data were taken with NASA Langley's airborne HSRL-2 instrument on September 24, 2016.