Radiative Strength Research Articles

Electromagnetic and Chemical Reactions of Unsteady Viscoelastic Flow of MHD Walter's‐B Through Vertical Porous Plates

ABSTRACTThis study examines the transient magnetohydrodynamic (MHD) flow of Walter's‐B viscoelastic fluid over a vertical porous plate within a porous medium, considering the effects of radiation and chemical processes. The nonlinear flow control equations are solved using a closed‐loop method, producing detailed numerical solutions for velocity, temperature, and concentration profiles. Velocity decreases with increasing permeability (K), Schmidt number (Sc), radiation (R), and magnetic field strength (M). In contrast, it increases with higher Prandtl number (Pr), permeability (K), and time (t). Temperature decreases with higher radiation but rises with Prandtl number and time. Concentration decreases with higher permeability and Schmidt number but increases with time. Notably, an increase in the Brownian motion parameter enhances heat and momentum transfer, thickening the velocity and thermal boundary layers. This research has practical applications in fields, such as blood oxygenators, chemical reactors, and polymer processing industries. The novelty of the study lies in its integration of radiation, chemical processes, and MHD flows in the analysis of viscoelastic fluids, a topic that has not been widely explored in previous studies. Future research could focus on optimizing MHD Walter's‐B viscoelastic flow systems, with particular attention to the effects of magnetic field strength and viscoelastic parameters on flow behavior.

Examining astrophysical gas cloud collapse using an optical depth-scaled, x-ray-irradiated, carbon-foam sphere

When stellar radiation interacts with a molecular cloud, the cloud's fate depends on the strength of the incident radiation and the radiation's mean-free-path within the cloud [F. Bertoldi, Astrophys. J. 346, 735–755 (1989)]. Under the right conditions, the radiation compresses the cloud and a star formation may occur. Where and when the stellar formation occurs in the cloud's collapse are open questions. Direct observation of the complete star–cloud lifecycle is nearly impossible due to the immense timescales and distances over which the interaction occurs. Laboratory astrophysics offers a way to investigate such a system by scaling the important astrophysical parameters to the laboratory. This work describes laboratory experiments to study the radiation-driven implosion of clouds, using x rays from a laser-irradiated, thin, gold foil as a surrogate star and a carbon-foam sphere as a surrogate cloud. An optically thick system, theoretically corresponding to a star-forming regime, was selected by choice of the foam density. Gold foil and sphere motions were imaged by x-ray radiography. Radiographic images show the formation of an interface between rarefied gold and carbon plasmas, a shock moving into the sphere, and a blunting of the initial sphere's shape. Measurements show that the shock moved linearly around 64 μm/ns into the sphere, and the gold–carbon interface formed by 2 ns at the sphere edge remained stationary. The deformation of the sphere was driven by the incident radiation and not by mechanical pressures applied by gold plasma. The blunting of the sphere was likely due to the geometric reduction of flux near the sphere's poles. Higher x-ray flux near the sphere's equator caused high compression and a faster shock, which flattened the sphere. We will discuss the results and implications of our observations.

The radiative torque spin-up efficiency of ballistic dust-grain aggregates

It is quintessential for the analysis of the observed dust polarization signal to understand the rotational dynamics of interstellar dust grains. Additionally, high rotation velocities may rotationally disrupt the grains, which impacts the grain-size distribution. We aim to constrain the set of parameters for an accurate description of the rotational spin-up process of ballistic dust grain aggregates driven by radiative torques (RATs). We modeled the dust grains as complex fractal aggregates grown by the ballistic aggregation of uniform spherical particles (monomers) of different sizes. A broad variation of dust materials, shapes, and sizes were studied in the presence of different radiation sources. We find that the canonical parameterization for the torque efficiency overestimates the maximum angular velocity $ RAT $ caused by RATs acting on ballistic grain aggregates. To resolve this problem, we propose a new parameterization that predicts $ RAT $ more accurately. We find that RATs are most efficient for larger grains with a lower monomer density. This manifests itself as a size- and monomer-density dependence in the constant part of the parameterization. Following the constant part, the parameterization has two power laws with different slopes that retain universality for all grain sizes. The maximum grain rotation does not scale linearly with radiation strength because different drag mechanisms dominate, depending on the grain material and environment. The angular velocity $ RAT $ of individual single dust grains has a wide distribution and may even differ from the mean by up to two orders of magnitude. Even though ballistic aggregates have a lower RAT efficiency, strong sources of radiation (stronger than $ 100$ times the typical interstellar radiation field) may still produce rotation velocities high enough to cause the rotational disruption of dust grains.

Impact of nuclear level density and radiative strength function models on the S factors of (α, γ) reactions relevant to p-nuclei production

Abstract The astrophysical S factors of (α, γ) reactions are crucial inputs to nuclear reaction network simulations for studying p-nuclei production. Previous work revealed considerable discrepancies between theoretical and experimental S factors using different nuclear level densities (NLD) and radiative strength functions (RSF). Accordingly, in this article, we studied the influence of six RSF and four NLD models on the astrophysical S factors of (α, γ) reactions on 16 target nuclei. The microscopic NLD and RSF models under investigation are based on the Hartree–Fock + Bardeen-Cooper-Schrieffer (HFBCS) and Hartree–Fock-Bogulubov (HFB) mean-field calculations. The obtained results have shown that within the α-OMP proposed in Nhu Le and Quang Hung (2022 Phys. Rev. C 105 014602), RSF and NLD models used in the S factor computation yield root mean square (rms) deviations of less than 0.750, and phenomenological NLD and RSF models provide better predictions for astrophysical S factors than microscopic ones in all cases considered. More research is needed on NLD and RSF models to improve prediction accuracy and reduce deviations in calculations of the S factors of radiative α captures.

Multi-criteria decision analysis using GIS in assessing suitability for a solar-powered biomass briquetting plant in the Gambella region, Ethiopia

Biomass briquetting presents a promising avenue for alternative cooking energy, enhancing livelihoods, and fostering sustainable development. This study underscores the abundant biomass resources in the Gambella region, primarily composed of savanna and woody savanna, which encompass 77 % of the land area, consisting mainly of forest and agricultural waste. Leveraging these resources can ensure a renewable and sustainable cooking energy supply, aligning with Sustainable Development Goals (SDGs) related to clean energy and environmental conservation. Consequently, this thesis endeavors to identify optimal sites for establishing solar-powered non-wooden biomass briquetting plants across the region. Various spatial and non-spatial datasets, including solar radiation, slope, land use/land cover (LULC), and proximity to roads, rivers, and towns, were utilized for area delineation and mapping. Parameters such as solar radiation, slope, and river streams were derived from 30 m resolution digital elevation models (DEMs). The Analytical Hierarchy Process (AHP) was employed to calculate criteria weights for overlay analysis, resulting in a suitable solar farm site map. The study reveals that land use/land cover exerts the most significant influence, with a weight of 46.58 %, followed by solar radiation strength (20.42 %), slope (15.52 %), proximity to roads (8.26 %), proximity to rivers (5.46 %), and proximity to towns (3.77 %). By integrating parameter suitability and weight assignment in ArcGIS spatial analysis, a suitability map was generated, highlighting highly suitable areas predominantly along the North-South axis through central Gambella. This area covers approximately 12,094.49 km², constituting 47 % of the study area. These findings have practical implications, as they can inform local policymakers and actors in strategically addressing the region's dire need for sustainable cooking energy. This contribution can support the development of localized renewable energy strategies and promote long-term energy security in line with local energy policies.

INTEGRAL YIELDS OF PHOTONEUTRON REACTIONS ON TIN ISOTOPES 118Sn AND 124Sn IN THE NEAR-THRESHOLD ENERGY REGION

The integral yields of the photonuclear reactions 118Sn(,n)117mSn and 124Sn(,n)123mSn, which are of interest for studying scenarios of the formation of atomic nuclei in stars, are measured in the near-threshold energy region. The experimental data are compared with the results of theoretical calculations performed using the TALYS nuclear reaction code. The dependence of theoretical predictions on the choice of models of the nuclear level density and the radiative strength function is investigated.

Determinations of transition probabilities and oscillator strengths of some levels in Eu I

Through combining experimental branching fractions (BFs) with radiative lifetimes, transition probabilities and oscillator strengths of Eu I for 39 lines from 16 excited levels were derived for the first time. The energies range from 27852.90 to 41443.70 cm-1. The BFs were determined in this work using the Fourier transform spectra available from National Solar Observatory database, and the lifetimes were obtained from literature. Furthermore, BFs for 22 lines, previously reported in the literature, were also determined for comparisons. The new results reported in this work will enrich spectral database and are expected to be widely used in many fields.

Numerical investigation of electromagnetic [Cu + TiO2/H2O]h hybrid nanofluid flow with solar radiation over an exponential stretching surface

AbstractThe idea of a hybrid nanofluid (HNF) has sparked curiosity among many scientists because of its ability to enhance thermal characteristics, leading to elevated rates of heat transfer (HT). These HNFs are utilized in various engineering and industrial settings, such as electronics cooling, manufacturing, naval structures, biomedical applications, and drug delivery. The current study investigates the analysis of irreversibility in EMHD [Cu + TiO2/H2O]h flow over a stretching sheet with radiation and viscous dissipation. The governing PDEs are converted into ODEs using similarity variables. These ODEs are then solved using the RKF method along with a shooting technique. The effects of different physical parameters on the velocity and temperature distributions of the HNF, as well as on HT and surface drag force, are thoroughly examined and presented in graphs. The velocity of [TiO2/water]n flow declines as the magnetic field strength rises, but it rises with greater electric field values for [Cu + TiO2/water]h. The temperature of the [Cu + TiO2/water]h increases with elevated levels of radiation, Eckert number, and heat generation strength. Higher Reynolds and Brinkman numbers result in a rise in entropy generation for [Cu + TiO2/H2O]h, whereas the Bejan number decreases to the same extent. The HT rate in [Cu + TiO2/H2O]h increases by 3.05% as the Eckert number rises, while it drops by 4.01% when there is significant thermal radiation. Skin friction reduces by 3.21% in [TiO2/water]n as the electric field strength increases, whereas it decreases by 4.05% with an increase in magnetic field strength. These discoveries offer valuable perspectives on furthering the utilization of HNFs in engineering and industrial operations.

Kaleidoscope of irradiated disks: MUSE observations of proplyds in the Orion Nebula Cluster

In the Orion Nebula Cluster (ONC), protoplanetary disks exhibit ionized gas clouds in the form of a striking teardrop shape as massive stars irradiate the disk material. We present the first spatially and spectrally resolved observations of 12 such objects, known as proplyds, using integral field spectroscopy observations performed with the Multi-Unit Spectroscopic Explorer (MUSE) instrument in Narrow Field Mode (NFM) on the Very Large Telescope (VLT). We present the morphology of the proplyds in seven emission lines and measure the radius of the ionization front (I-front) of the targets in four tracers, covering transitions of different ionization states for the same element. We also derive stellar masses for the targets. The measurements follow a consistent trend of increasing I-front radius for a decreasing strength of the far-UV radiation as expected from photoevaporation models. By analyzing the ratios of the I-front radii as measured in the emission lines of Hα, [O I] 6300 A, [O II] 7330 A, and [O III] 5007 A, we observe the ionization stratification, that is, the most ionized part of the flow being the furthest from the disk (and closest to the UV source). The ratios of ionization front radii scale in the same way for all proplyds in our sample regardless of the incident radiation. We show that the stratification can help constrain the densities near the I-front by using a 1D photoionization model. We derive the upper limits of photoevaporative mass-loss rates (Ṁloss) by assuming ionization equilibrium, and estimate values in the range 1.07–94.5 × 10−7 M⊙ yr−1, with Ṁloss values decreasing towards lower impinging radiation. We do not find a correlation between the mass-loss rate and stellar mass. The highest mass-loss rate is for the giant proplyd 244–440. These values of Ṁloss, combined with recent estimates of the disk mass with ALMA, confirm previous estimates of the short lifetime of these proplyds. This work demonstrates the potential of this MUSE dataset and offers a new set of observables to be used to test current and future models of external photoevaporation.

Preparation of barium alumino-silicate based ceramsite from bauxite, coal gangue and barite: Physical properties, microstructure, and γ-ray shielding behavior

Improving the strength of radiation shielding concrete and the safety of corresponding structures is crucial. However, radiation shielding ultra-high performance concrete (RS-UHPC) often faces the issues of high volume shrinkage and easy cracking. Using barium alumino-silicate-based ceramic as aggregate in concrete is a promising solution for its internal curing effect and excellent radiopacity. In this study, a barium alumino-silicate-based ceramsite (BASC) was developed using bauxite, coal gangue, and barite. The effects of boric anhydride (2 %, 5 %, 8 %), barite powder dosages (20 %, 40 %, 60 %, 80 %), and sintering temperature (1260°C, 1280°C, 1300°C, 1320°C) on the apparent density, compressive strength, and water absorption of the ceramsite were investigated. The microstructure and reaction mechanism of the BASC were analyzed using TG-DSC, XRD, SEM-EDS, and low-field NMR techniques. The results showed that the addition of barite increases the apparent density of ceramsite but decreases its strength. The ceramsite with 60 % barite calcined at 1320°C has a density of 3120 kg/m3, water adsorption of 11.19 %, and a cylinder compressive strength of 11.2 MPa. The prepared BASC ceramsite exhibits a highly connected pore structure and good water retention capacity at this temperature. The ceramsite has many closely packed celsian and corundum crystallites, which give it good mechanical strength. Finally, the gamma-ray attenuation and autogenous shrinkage of UHPC prepared with this ceramsite was tested. The linear attenuation coefficient of the BASC-UHPC is 0.176 cm−1, comparable to UHPC prepared with lead glass. The BASC replacement for quartz sand reduces the 28d autogenous shrinkage of UHPC by 55.0 %. The research results can guide the application of BAS-based ceramsite in radiation-shielding ultra-high performance concrete.

Analyzing the long-term effects of e-glass mortar on sustainability and radiation shielding using ANOVA.

Significant investigations were performed on the use and impact on physical properties along with mechanical strength of the recycled and reused e-glass waste powder. However, it has been modeled how recycled display e-waste glass may affect the characteristics and qualities of dune sand mortar. This study investigates the long-term feasibility of using recycled display e-glass waste as a partial substitute for dune sand at varying percentages (5%, 10%, 15%, and 20%). The main focus is on evaluating its effectiveness in radiation shielding, strength properties, and durability for long-term development under the heating environmental process. Statistical analyses, including analysis of variance, are used to assess the significance of factors and their interactions on these characteristics. Additionally, a regression equation derived from the model offers insights into the quantitative relationship between the factors and properties. The results of the experiments led to the conclusion that the most effective proportion of e-glass waste to include in mortar is 20%, with the weight of dune sand. Including e-glass waste, they significantly increased the five characteristics of the mortar, making it suitable for high-strength mortar applications continue up to 68MPa. The ANOVA model used in this study was trained using the same experimental research design and was critical in predicting the properties of the mortar. The model produced an accurate result with an R2 value greater than 0.99. E-glass replacements exhibit remarkable radiation shielding, characterized by pozzolanic activity and superior internal bonding due to its compact texture, contributing to enhanced long-term strength.

Application of microwave technology to extract pure sesame oil

The purpose of the study was to use microwave technology to extract pure sesame seed oils. The findings of investigations on how microwave treatment affects sesame seed yields for oil and cake are reported. It has been demonstrated that the radiation strength and duration of processing have a major impact on oil production. Studies have shown the possibility of increasing the yield of sesame oil, compared to obtaining oil with preliminary heat treatment of sesame seeds, by 1.97% by treating them with steam and subsequent treatment with microwave radiation for 12 minutes. In these circumstances, the oil output is 33.72%, the cake yield is 66.28%, and the moisture content is reduced to 3.77%. The oil content of the seeds, the intensity of the microwave radiation, and the length of the process are the primary factors affecting the amount of oil released. The best technical parameters have been determined, at which 33.72% of the oil and 66.28% of the cake are extracted.

Efeito agudo da cinesioterapia e da eletroestimulação neuromotora sobre a variação térmica de indivíduos com insuficiência venosa crônica

Abstract Introduction: Chronic venous insufficiency (CVI) is a change in the venous system that can be caused by dysfunction in the triceps surae muscles. Objective: To evaluate the acute effect of neuromuscular electrical stimulation and kinesio-therapy on ankle joint flexibility, infrared radiation and triceps surae strength in individuals with CVI. Methods: We conducted a comparative study, in which ankle flexibility, dorsiflexion and plantar flexion strength and thermal variations of the calf were evaluated. An electrical stimulation session (1 kHz Aussie current with burst = 2 ms) was performed on the right lower limb (EG - electrostimulation group) and kinesio-therapy on the lower limb left (KG - kinesiotherapy group), with stretching and metabolic exercises involving the ankle. Results: Nineteen female patients were evaluated. Analysis of ankle flexibility did not demonstrate significant changes. In the assessment of muscle strength, there was no difference between groups, and in the intragroup assessment, only KG showed an increase for dorsiflexion (before treatment: 11.6 ± 3.5; 24 h after: 13.5 ± 3.0; p = 0.02), and for plantar flexion (before: 11.8 ± 6.3; 24 h later: 14.4 ± 5.06; p = 0.04). Regarding thermography, there was no intragroup difference, while in the intergroup assessment, KG showed an increase in temperature immediately and 24 h later (0.44 ± 0.68, p = 0.01 and 0.25 ± 0.83, p = 0.07, respectively). When analyzing the correlation between dorsiflexion and plantar flexion strength of both lower limbs with total range of motion of the right and left ankle, a positive correlation was observed only between the plantar flexion strength immediately after and 24 h later with range of motion and ankle in KG (r = 0.49, p = 0.03 and r = 0.51, p = 0.03, respectively). Conclusion: There were no significant differences between kinesiotherapy and electrotherapy when analyzing joint flexibility and muscle strength, but kinesiotherapy was superior in increasing calf temperature before and after 24 h of intervention.

Imprint of pairing correlation in (n, γ) and Maxwellian-averaged cross sections of an odd-odd 166Ho nucleus

The present paper investigates the impact of pairing correlation on the nuclear level density (NLD) and radiative strength function (RSF) of an odd-odd and rare-earth 166Ho nucleus. By employing the exact thermal pairing (EP) solution in conjunction with both the temperature-dependent independent-particle model (EP+IPM) for the NLD and the phonon damping model (EP+PDM) for the RSF, we achieve good agreement with the experimental NLD and RSF data, which have been recently extracted by using the Oslo method. Notably, without adding any extra parameters, our calculations successfully reproduce the pygmy dipole resonances (PDR) and a portion of the strength around the region of scissor resonance (SR) in the RSF. This suggests that the SR in this nucleus may be less pronounced than that obtained in the previous analysis within the phenomenological model. These features are the consequences of the EP and the couplings of the PDM phonon to all the particle-hole (ph), particle-particle (pp), and hole-hole (hh) configurations within the EP+PDM, thus insisting on the importance of the underlying physics involved in this model. Utilizing the obtained NLD and RSF, we predict the 165Ho(n,γ)166Ho and Maxwellian-averaged cross sections, which exhibit remarkable agreement with all the available experimental data from the Experimental Nuclear Reaction Data and Karlsruhe Astrophysical Database of Nucleosynthesis in Stars. These results reflect the imprint of the pairing correlation on those quantities.

The Structure Function of Mid-infrared Variability in Low-redshift Active Galactic Nuclei

Using the multi-epoch mid-infrared (MIR) photometry from the Wide-field Infrared Survey Explorer spanning a baseline of ∼10 yr, we extensively investigate the MIR variability of nearby active galactic nuclei (AGNs) at 0.15 < z < 0.4. We find that the ensemble structure function in the W1 band (3.4 μm) can be modeled with a broken power law. Type 1 AGNs tend to exhibit larger variability amplitudes than type 2 AGNs, possibly due to the extinction by the torus. The variability amplitude is inversely correlated with the AGN luminosity, consistent with a similar relation known in the optical. Meanwhile, the slope of the power law increases with AGN luminosity. This trend can be attributed to the fact that the inner radius of the torus is proportional to the AGN luminosity, as expected from the size−luminosity relation of the torus. Interestingly, low-luminosity type 2 AGNs, unlike low-luminosity type 1 AGNs, tend to exhibit smaller variability amplitude than do high-luminosity AGNs. We argue that either low-luminosity type 2 AGNs have distinctive central structures due to their low luminosity or their MIR brightness is contaminated by emission from the cold dust in the host galaxy. Our findings suggest that the AGN unification scheme may need to be revised. We find that the variability amplitude of dust-deficient AGNs is systematically larger than that of normal AGNs, supporting the notion that the hot and warm dust in dust-deficient AGNs may be destroyed and reformed according to the strength of the ultraviolet radiation from the accretion disk.

Multipurpose elastic metallized fabrics

This article substantiates the metallization of fabrics, which can be used to protect products from corrosion, rotting, erosion, and also be used for decorative and other purposes. The metallization process has been studied, which consists of applying thin layers of various metals to fabric: aluminum, chromium, cadmium, tin, zinc, silver, gold and other metals, as well as some alloys and inorganic substances or, instead, organic threads that penetrate very finely into textile. The article presents samples of metallized fabrics, as well as fabrics with shielding properties. As a result, a table is presented that characterizes the reduction in the strength of electromagnetic radiation when using such fabrics.

Influence of polypropylene fibers on the mechanical properties of radiation shielding concrete with barite aggregates

The brittleness of barite aggregates leads to inferior strength and toughness of radiation shielding concrete with barite aggregates (RSBC), which limits its application in high-pressure and high-heat nuclear engineering. This study aims to investigate the influence of polypropylene fibers on the mechanical properties of RSBC, and the effects of fiber type (PR40 and TMA20) and fiber content (3–9 kg/m3) on the mechanical properties of RSBC with water-to-binder (w/b) ratios of 0.44 and 0.39 are discussed. The microstructure of polypropylene fiber-reinforced RSBC was analyzed through scanning electron microscopy, revealing the underlying reinforcement mechanism of polypropylene fibers. The applicability of prediction formulas from typical codes was evaluated based on experimental data, and a reliable prediction model for the mechanical properties of RSBC was established. The findings showed that incorporating polypropylene fibers can significantly improve the compressive strength, splitting tensile strength, and flexural strength of RSBC. The addition of 9 kg/m3 PR40 and TMA20 fibers increased the 28-day compressive strength of RSBC by 17.9%–19.8% and 9.5%–16.2%, respectively; the 28-day splitting tensile strength increased by 12.1%–27.7% and 9.3%–26.1%, respectively; and the 28-day flexural strength increased by 19.3%–25.0% and 7.0%–13.5%, respectively. Adding PR40 fibers with a lower slenderness ratio yielded significantly better mechanical properties. Polypropylene fibers form a three-dimensional network structure in the concrete, acting as a bridge between the aggregate and cement mortar, enhancing the stability of interfacial transition zones, thereby effectively improving the macroscopic mechanical performance of RSBC. The mechanical property prediction models of EC 2 and GB 50010 for RSBC exhibit deviations, while the ACI 318 splitting tensile strength model and the flexural strength model established in this research demonstrate good predictive performance.

Импульсные источники ИК-излучения с разрядом в смеси паров щелочных металлов

The paper presents results of research aimed at improving the serial pulsed sources of the IR-radiation based on a discharge in the cesium-mercury-xenon vapor mixture. To create the environmentally friendly gas-discharge source and increase the peak radiation strength, it proposes to replace the mercury buffer in a serial lamp with the rubidium vapor. Based on the thermodynamic analysis, necessity of using cesium as the main component in the plasma-forming medium of IR-radiation pulsed sources was proved. It was established that introduction into the cesium discharge of less than the 25 % (wt.) rubidium provided the required cesium vapor pressure and the plasma thermal conductivity. It was shown that the mass of the alloy with cesium played an important role in the discharge transition from unsaturated to the saturated vapors. Comparison results are presented in peak intensity of the studied IR-radiation gas-discharge lamps depending on amplitude and duration of the supply voltages in the repeated pulsed mode. A technique was developed to compare energy efficiency of the discharges under study, and the spectral research was performed confirming advantages of the IR-radiation pulsed source based on the cesium-rubidium-xenon discharge by the serial gas-discharge lamps

Investigate Cross-sections for (α, γ) reactions on p-nuclei 90Zr, 121Sb, 151Eu, and 162Er using Different Models of Radiative Strength Functions

In this work, we examine cross sections for (α, γ) reactions on p-nuclei, including 90Zr, 121Sb, 151Eu, and 162Er at astrophysically relevant energies. By using our recently developed α optical model potential (α-OMP), the (α, γ) cross sections were calculated within six models of radiative strength functions (RSF) which consisted of the microscopic HFB-QRPA model based on the BSk-14 Skyrme force, the HF-BCS theory using Skyrme parameters, the EGLO model, SMLO model, the empirical SMLO (SMLOg) and global semi-microscopic (D1M-QRPAg) models. The numerical results is then compared to the measured data of (α, γ) cross sections. For the considered (α, γ) reactions, the EGLO, SMLO, and HFB results are typically greater than the measured data. In addition, the comparison has indicated that the RSF models of SMLOg and D1M-QRPAg best fit the measured data with rms smaller than 0.2 within our proposed α-OMP. Therefore, for the (α, γ) reactions on the selected targets, RSF models of SMLOg and D1M-QRPAg are strongly recommended. The results are significant for a further systematic examination to evaluate which RSF model is most appropriate for studying (α, γ) reactions on p-nuclei in general.

Фильтрация сигналов при скачкообразных мультипликативных помехах

The problem of constructing the approximately optimal Bayesian algorithm of filtering the output signal for a linear stochastic dynamical system is solved. Non-linear mixture of the output signal and of the multiplicative interference was measured. This interference is a continuous-valued random process with the unknown distribution law within the given limits of [c(1), c(2)], c(1) &gt; 0, c(2) &gt; 0, and in the frequency range of [0, ∆ω]. The filtering algorithm is synthesized by the approximately optimal signal estimation method based on the theory of systems with random jump structure and the method of two-time parametric approximation of the phase coordinates probability distribution. The method consists in approximate replacement of the unknown probability densities of phase coordinates by the known distribution laws with the unknown mathematical expectations and covariances determined as a result of solving the problem. The proposed approximate-optimal filtering algorithm is based on replacement of the continuous-valued multiplicative interference by a random jump process, i.e., Markov chain with two states c(1), c(2) and equal intensities of transitions from one state to another q′ = 2∆ω. Conditional probability densities of the output signal for fixed states of the Markov chain c(1), c(2) are approximated by gamma distributions that depend on mathematical expectations and variances of the x(t) signal at the fixed c(1), c(2) and measurements x(t) in a mixture with the Markov jump interference. An example of constructing an algorithm for evaluating the distance from an aircraft to the object based on object irradiance measurement by the infrared direction finder was considered. Irradiance was equal to the radiation strength ratio to the square of the distance. Radiation strength, i.e., multiplicative interference, was the random process with unknown continuous distribution in a limited range. The approximate-optimal filter was constructed for distance evaluation by replacing this process with a two-state Markov chain and approximating the distance probability density by the Rayleigh distribution