Dispersion Analysis Method Research Articles

Improved mechanical and microscopic properties of ultra-high-performance concrete with the addition of hybrid alkali-resistant glass fibers

Ultra-high-performance fiber-reinforced concrete (UHPFRC), wherein steel fibers are a primary component, is a new cementitious material with high tensile strength and impact resistance. However, steel fibers are susceptible to corrosion in the alkaline environment of concrete matrices. By contrast, alkali-resistant glass fiber (ARGF) exhibits better corrosion resistance. However, few studies have explored the effects of ARGF on UHPFRC, leaving the optimum ARGF content and its enhancement mechanism unclear. Therefore, this study proposes a UHPFRC design that utilizes AR-GF in place of steel fibers. The effects of different types, lengths, and admixtures of AR-GF are investigated using mechanical tests, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results show that the splitting tensile strength and flexural strength of the UHPFRC increase with fiber length and fiber dosage. The optimum fiber mixing ratio is 30 kg/m3 of 12 mm-long Anti-Crak® 62.4 combined with 0.05 kg/m3 of 6 mm long Anti-Crak® HD, leading to a 23.3 % increase in splitting tensile strength and 15.8 % increase in flexural strength compared to those of undoped concrete. By analyzing the ARGF dispersion pattern at the fracture surface of the flexural test, the ARGF dispersion analysis method was proposed. SEM shows that the ARGF is coated with C-S-H, which increases its adhesion to the concrete matrix. XRD confirms that ARGF does not affect the hydration reaction of the cement in the UHPFRC. Finally, a model of ARGF-reinforced UHPFRC is established to elucidate the reinforcing mechanism. This study provides guidance and a reference for the application of UHPFRC in engineering projects.

Simulations of nerve signal propagation in axons

PurposeIn the literature, soliton solutions of the Heimburg–Jackson model have been proposed by Drab et al. (2022), but for the considered models, i.e. Eq.(1) and Eq.(2), the existence of solitons, the dispersion analysis and the pseudospectral method have been studied (Engelbrecht et al., 2006, 2018, 2020; Tamm et al., 2017, 2022; Peets et al., 2013). Therefore, the gap should be filled by this work.Design/methodology/approachWhen nonlinear terms, dissipative terms and forcing terms are ignored, the system (Eq.(2)) reduces to a single, sixth-order partial differential equation (Tamm et al., 2022). In this work, our aim is to propose analytical solutions in the explicit form via ansatz-based method. Therefore, the parameter effects in wave profile will be proposed clearly in figures.FindingsWhile progress has been made in signal propagation in nerves, thanks to many experimental studies and theoretical predictions over the last two centuries, the results obtained in this study may answer new questions that arise.Originality/valueIn the literature, the existence of solitons, dispersion analysis and pseudospectral method have been investigated for the Heimburg-Jackson model (Engelbrecht et al., 2006, 2018, 2020; Tamm et al., 2017, 2022; Peets et al., 2013), and this study fills the gap in soliton solutions. Additionally, when nonlinear terms, dissipative term and forcing terms are ignored, the system (Eq.(2)) reduced to a single equation that is sixth-order partial differential equation (Tamm et al., 2022). In this work, our aim is to propose analytical solutions in the explicit form via ansatz-based method. Therefore, the parameter effects in wave profile will be proposed clearly in figures.

МОДЕЛЮВАННЯ ТА ОПТИМІЗАЦІЯ РЕЖИМУ ТЕРМООБРОБКИ ТРУБЧАСТИХ ЕЛЕМЕНТІВ ФЕРМЕННИХ КОНСТРУКЦІЙ ЛІТАЛЬНИХ АПАРАТІВ З ВУГЛЕПЛАСТИКУ

The article analyzes the current state of development of dimensionally stable tubular elements (TE) and technological problems arising during their production. It is shown that along with empirical methods of studying the influence of various technological schemes on the dimensional stability of tubular elements, it is useful to use the optimal temperature-time mode for heat treatment and, based on it, select the optimal technological scheme. Modeling and determination of the optimal mode of heat treatment of tubular elements were performed. The study of the TE heat treatment mode was carried out in two stages, first by methods of mathematical modeling and optimization, and then by empirical enumeration of various technological schemes. At the first stage, the material properties, which are parameters of the mathematical model, were studied, and the optimal curing modes were calculated. At the second stage, the calculated optimal curing modes were supplemented with various technological methods that cannot be mathematically modeled, and a study was carried out on the influence of the resulting combined heat treatment mode on the geometric characteristics and dimensional stability of carbon fiber TE. The mathematical model of the process of heat treatment and curing of TE in a heat chamber, when heated by a heating air flow, is a system of differential equations: thermal conductivity and curing kinetics. A mathematical model of the process of heat treatment of tubular elements manufactured by the winding method is proposed, the ways of optimizing the curing mode of carbon fiber TE are shown. A numerical calculation of temperature-conversion fields during curing and calculation of optimal curing modes of tubular elements are performed taking into account various process schemes. The values of heat capacity C and thermal conductivity l are calculated depending on the temperature T, the degree of curing b and the filling coefficient g, Безфітингова ферма з вуглепластику Безфітингова ферма з вуглепластику Безфітингова ферма з вуглепластику the power of heat release W and the thermal effect of the curing reaction Q of carbon fiber. Optimum curing modes for a plate made of composite polymer material are obtained, calculated from the data obtained as a result of studying material samples. Temperature-time curing modes are obtained, which are optimized for different thicknesses of the studied material. The statistical hypothesis about the significance of the influence of the process flow chart and reinforcement pattern on the wall thickness of a tubular element and its compressive strength was proved by the dispersion analysis method. The influence of process flow charts and heat treatment modes on the geometric and mechanical characteristics of carbon fiber tubular elements of aircraft truss structures was studied. The statistical hypothesis about the significance of the influence of the process flow chart and reinforcement pattern on the deviation of the wall thickness of tubular elements and their strength characteristics was tested. The significance of the influence of process flow charts with different heat treatment modes on the average wall thickness of a carbon fiber tubular element was statistically proven.

Comparative immunohematological profile of <i>Pelophylax ridibundus</i> and <i>P. lessonae</i> (Amphibia: Ranidae) infected with hemoparasites

The direction of adaptive reactions of healthy and Hepatozoon spp.-infected green frogs from water bodies of the Nizhni Novgorod region with various hydrochemical conditions was studied. During the observation period, infection of pool frogs and an increase in the total population indicators of infection of male and female marsh frogs with Hepatozoon spp. were revealed. Hypertrophy of the morphometric parameters of infected blood erythrocytes compared with healthy cells was revealed in marsh frogs. The content of neutrophil granulocytes in the blood of infected marsh frogs was higher compared to healthy individuals, while the level of immune complexes did not differ. In infected pool frogs, an increase in the level of large immune complexes in the blood serum and the enlargement index was revealed compared to healthy ones against the background of a general decrease in the body’s resistance in conditions of severe pollution of their habitat with heavy metals and sulfates. For marsh frogs, a correlation was established between the proportion of infected erythrocytes and the content of myelocytes and young forms of neutrophils in the blood; while for pool frogs – with the content of neutrophils and the enlargement index of immune complexes. The method of multifactorial dispersion analysis revealed a significant influence of such factors as gender and the interaction of gender/infection with hemoparasites on the immune status of amphibians.

Numerical study on guided-wave reflection and transmission at water pipe joint using hybrid finite element method

AbstractThis study investigates guided-wave reflection and transmission at a water pipe joint. The system comprises a linearly elastic pipe filled with water with a joint that is modeled as a discontinuity of the solid region. Wave reflection and transmission are solved using the finite element method (FEM) with radiation conditions for reflected and transmitted guided waves into infinite waveguides. For the radiation conditions, the reflected and transmitted waves are expressed by modal expansion using the semi-analytical finite-element (SAFE) dispersion analysis method. This study extends the hybrid SAFE-FEM to the coupled fluid–solid axisymmetric problem. Numerical results demonstrate that the hybrid SAFE-FEM provides sufficiently accurate solutions. The propagation modes, similar to the modes in a solid pipe, are strongly or perfectly reflected by the joint. However, the modes are transmitted through the joint with little scattering after they converge to the modes in a water bar. The crossing of dispersion curves with those for modes in a solid pipe causes mode conversion and induces scattering attenuation.

Interaction of integral parameters of physical state and biological age of students aged 17-19 years old in the process of adaptation to standard and experimental physical education programs

Background and Study Aim. The process of adaptation to physical education programs is a critical factor influencing the health and physical development of students. Understanding how these programs affect both the physical state and biological age of students can significantly improve their effectiveness. The aim of the study is to investigate the interaction between integral parameters of physical state (PS) and biological age (BA) of students aged 17-19 years old in the process of adaptation to standard and experimental physical education (PE) programs. Material and Methods. The study involved 140 first-year students of the National University of Telecommunications - 80 males and 60 females. In the course of the research, the indices of functional state, physical fitness (PF) and physical development (PD), biological age (BA) were recorded in young men and women of the control (CG) and experimental (EG) groups. To process the experimental material, methods of dispersion and canonical analysis were used and multiple correlation and determination coefficients were calculated. Results. It was revealed that the impact of PS integral parameters on students' BA is stronger than the inverse influence of BA on PS parameters. The degree of BA reduction under the influence of the studied factors is most pronounced in the EG of girls and boys. The variability of the group of PD and PF indices is accompanied by the variability of most of the BA parameters’ dispersion in all studied groups of students. The factor of gender has the greatest impact on the BA of students. Girls have lower initial values of BA and it’s a more pronounced decrease by the end of the experiment. The effectiveness of the impact of an aerobically oriented experimental program on the improvement of students’ PS and reduction of BA was confirmed. Under the influence of the experimental program, the BA of EG girls decreases to a greater extent in comparison with EG boys and students of both control groups. Changes and differences in BA of boys and girls of EG and CG are due to the combined impact of the factor of PE software and that of adaptation changes of students' PS in the annual process of PE. In the group of boys and girls more pronounced influence on BA in the course of the experiment was produced by the factor of software and adaptation changes, respectively. Conclusions. The gender factor has the strongest impact on students' BA - girls have lower initial values of BA and it’s a more pronounced decrease by the end of the experiment in comparison with boys. Adaptation changes of PS in the process of software implementation are accompanied by a decrease in BA in the experimental groups. One of the criteria and confirmations of the effectiveness of the developed PE program is the degree of mutual influence of PS integral parameters, which is most pronounced in the reduction of BA in the experimental groups of girls and boys.

SYNTHESIS OF MULTICOMPONENT HEAT-SHIELDING RADIATION-RESISTANT CERAMICS WITH VARIATION OF STOICHIOMETRY OF CERAMIC COMPONENTS

The paper presents the results of obtaining multicomponent heat-protective radiation-resistant ceramic materials based on the WO3–Bi2O3–ZnO–TeO2–CeO2–ZrO2 compounds obtained by mechanochemical solid-phase synthesis with further annealing at a temperature of 1000 °C. The introduction of doping substances into the structure in the form of metal oxides makes it possible to prevent undesirable structural changes in ceramics and improve the durability and stability of the system. The choice of the synthesis of ceramics based on zirconium oxide is associated with the presence of several valuable physical and mechanical properties of the substance, and, as a consequence, the possibility of application in the field of functional materials for use in a variety of technical fields. The processes of phase formation in multicomponent ceramics based on oxide refractory compounds (WO3, Bi2O3, ZnO, TeO2, CeO2, ZrO2) were studied by scanning electron microscopy, energy dispersive and x-ray phase analysis methods. Using a combination of the presented methods, the following results were obtained, which make it possible to comprehensively characterize the samples under study, as well as establish the dependence of the influence of variations in the oxides used on the phase composition and morphological features of the ceramics. Analysis of morphological parameters showed that with increasing dopant concentration, a denser structure of agglomerates is formed, which is associated with sintering of particles at higher dopant concentrations. According to the obtained results of energy dispersive analysis, it was found that the addition of ZrO2 results a slight redistribution of elements in the structure, so the atomic content of Ce, W, Bi, and Te decreased by 2.58; 3.38; 2.12; 1.91 times, respectively, and the atomic content of Zn increased by 1.32 times. Analysis of diffraction patterns showed that the studied samples WO3-Bi2O3-ZnO-TeO2-CeO2-ZrO2 are characterized by the content of Zn3(TeO6), ZnTeO3, CeO2, Bi2O3, Bi2WO6, ZnWO4, Ce5Zr3O16, ZnO, (Zr0.98Ce0.02)O2 phases.

Perinatal Consequences in Pregnant Women Suffering from Metabolic Syndrome

The aim of the study was to evaluate perinatal outcomes in pregnant women suffering from metabolic syndrome
 Material and methods. The study was carried out on the basis of Maternity House No. 7" (Odesa) in 2014-2021. 57 women with metabolic syndrome were examined. Anthropometric parameters, basic metabolism, leptin content and lipid profile, frequency of complications of pregnancy and childbirth were evaluated. Statistical processing was carried out by methods of dispersion and correlation analysis using Statistica 13.0 software (TIBCO, USA).
 Research results.
 The average age of the examined women was 27.4±1.1 years. Of them, 16 (28.1%) pregnant women were primiparous, and 41 (71.9%) pregnant women gave birth again. BMI in all women was above 25 kg/m2 (on average 29.2±0.6 kg/m2) with a fat content of 47.3±2.4%. During pregnancy, leptin level was on average 39.3±1.6 ng/ml, LDL content was 1.8±0.1 mmol/l. The presence of metabolic syndrome significantly increased the frequency of obstetric and perinatal complications. The possible relationship between the identified disorders and qualitative changes in the intestinal microbiome is discussed.
 Conclusions:
 
 In women with manifested metabolic syndrome, the course of pregnancy was complicated by preeclampsia in 24.6% of cases, placental dysfunction in 29.8% of cases. The threat of premature birth occurred in 40.4%, gestational diabetes – in 31.6% of women.
 With metabolic syndrome, the frequency of operative delivery increases to 35.1%. The main indications for a cesarean section were a clinically narrow pelvis, a severe form of preeclampsia, and weakness of labor that cannot be corrected with medication.
 During childbirth, women in labor with metabolic syndrome often experience such complications as weakness of labor (19.3%), premature discharge of amniotic fluid (24.6%). The main complication of the postpartum period was subinvolution of the uterus (15.8%).
 Most of the children born had signs of macrosomia, which closely depended on leptin concentration (r=-0.31).
 The proven existence of a strong correlation between the level of leptin production and LDL (rs=0.76).

Interrelations of physical state parameters and biological age of students in the process of physical education

Background and Study Aim. The objective of the study is to investigate the relationships of students' biological age (BA) with the parameters of functional and physical fitness (PF) in the process of adaptation to standard (university) and experimental physical education programs. Material and Methods. The studies were conducted at the National University of Telecommunications of Ukraine and involved 140 students aged 17-18 years old, comprising 80 boys and 60 girls. We recorded 55 indices of students' functional state and physical fitness, and determined their Body Mass Index (BMI). The experimental data were processed using methods of correlation, dispersion, and regression analysis. Mathematical models describing the relationships between BMI and key indicators of students' physical well-being were developed. Results. The impact of the program on 17-18-year-old students is marked by a decrease in BMI, an increase in the levels of physical fitness and overall well-being among both the experimental group of girls and boys. Additionally, there is a reduced correlation between BMI and the parameters of their physical health. The key indices of functional state and physical fitness determining the BMI of male and female students were identified. Multiple regression models were developed to illustrate the dependence of male and female BMI on somatic and functional indices. Quantitative characteristics of the degree of partial and total impact of key indices on male and female BMI were provided. It was found that the key indicators of students' physical state (PS) structure, which exerted the most significant influence on BMI, differ between young men and women. In young men, the key indicators influencing BMI include the following: Vital capacity (VC) accounts for 51.9% of BMI variation; self-perceived health status (SPHS) contributes 15.3%; static balancing (SB) affects 8.5%; inspiration breath-hold time (IBH) influences 8.4%; expiration breath-hold time (EBH) has a 0.8% impact; systolic blood pressure (SBP) plays a role with 4.6%; the number of sit-ups in 30 seconds (SU30s) is associated with 0.9%; and left hand muscle strength has a 0.6% influence. In girls, the key indicators are VC (34.5% of BMI variation), SBP (23.1%), and SB (7.9%). Conclusions. The experimental program of increased motor activity leads to an increase in the functional and motor capabilities of students, while simultaneously decreasing their BMI. Among the parameters studied, changes in vegetative parameters have the greatest impact on reducing students' BMI during the annual cycle of long-term adaptation to physical loads. In contrast, changes in somatic parameters and physical fitness parameters have a lesser influence on students' BMI. The calculated equations of multiple regression serve as model characteristics that reflect the relationships between BMI and the key indicators of functional state and physical fitness in 17-18-year-old students. These equations can be utilized to estimate, model, and predict the BMI of 17-18-year-old students of different genders when altering the parameters of their physical state in various conditions of daily life and activity.

A frequency-Hankel transform method to extract multimodal Rayleigh wave dispersion spectra from active and passive source surface wave data

Rayleigh wave dispersion energy spectra have been widely used to extract dispersion curves and invert underground S-wave velocity structures for engineering geophysics and seismology. We develop a frequency-Hankel (F-H) transform method to extract high-quality multimodal Rayleigh wave dispersion energy spectra from active and passive source Rayleigh wave data. The F-H transform method is inspired by the frequency-Bessel (F-J) transform method and considers the physical meaning of Green’s functions for Rayleigh wave dispersion analysis. The F-H transform method can naturally avoid crossed artifacts caused by converging waves on F-J spectrograms and obtain more multimodal dispersion spectra of the same quality with fewer Rayleigh wave data than the F-J transform method. Synthetic and field Rayleigh wave data from active and passive sources for near-surface exploration and ambient noise tomography are used to demonstrate the validity, accuracy, and applicability of the F-H transform method. The F-H transform method unifies the formulas of the F-J transform method and its modifications for active and passive sources of Rayleigh wave data. The F-H transform method is a robust and efficient multimodal Rayleigh wave dispersion analysis method for active and passive source Rayleigh wave data.

Изучение прочностных характеристик оттаивающих грунтов с учетом их снижения при динамическом воздействии

In recent years, despite the negative impact of global warming on permafrost, there has been an increase in the length of railways in the Arctic zone. The bearing capacity of thawing permafrost soils at the base of the roadbed is reduced, especially under the influence of increased vibrodynamic load, therefore, the study of their strength characteristics is becoming increasingly relevant. The article examines the adhesion and the angle of internal friction of thawing soil, and presents the results of triaxial tests using the method of orthogonal experiments. The patterns of changes in the strength characteristics of thawing soil under the influence of such factors as the initial temperature of soil samples, humidity and the load stage are determined. Based on the method of dispersion analysis (ANOVA), the influence of initial temperature of soil samples, humidity and the load stage on the strength characteristics of the soil was studied. Based on the results of triaxial tests, the regression equations of the dynamic coupling and the dynamic angle of internal friction were obtained. The results of the research can be used to calculate the bearing capacity of thawing permafrost soils at the base of the roadbed.

Влияние поверхностной модификации на морфологические характеристики и микротвердость стали ХВГ

During the experiment, carried out in two stages, a thin-film coating of molybdenum is obtained on substrates made of steel grade HVG. The first stage included preliminary ion implantation of molybdenum. The second stage is the production of a thin-film molybdenum coating by balanced magnetron sputtering. During the study using scanning electron microscopy, microphotographs are obtained that visually confirmed the uniformity and homogeneity of the thin-film coating. The values of average surface roughness Sa is obtained by probe microscopy suggest that it decreases after applying a thin-film coating. Using the energy dispersive analysis method, the mass concentration of molybdenum on the surface of the modified tool steel was determined, which is 92,4 %. Experimental modes of modification of KhVG steel with a thin-film coating have been obtained, which have a significant effect on the average roughness and microhardness of its surface. It has been shown that the experimental modes used in the work make it possible to obtain a strengthening of the surface of HVG steel after applying a thin-film coating of molybdenum, with preliminary ion implantation several times. The adhesion force between the thin-film coating and the HVG steel substrate is determined. High adhesion values obtained using the method proposed by Gerald Frankel from Ohio State University indicate good quality of the applied coating. All of the above indicates the prospects of using the above-mentioned methodology in the mechanical engineering industry.

Strategies for optimizing the single GdSrFeO4 phase synthesis

Abstract This work provides data on strategies for single GdSrFeO4 phase solid state synthesis. Earlier works have shown that under the solid-state synthesis conditions, the GdSrFeO4 preparation is hampered by the formation of non-target product: Gd2SrFe2O7. This work approach led to the solid-phase synthesis GdSrFeO4 scheme change. GdSrFeO4 was characterized by X-Ray, scanning electron microscopy/energy dispersive X-ray spectroscopy, dilatometry and complex thermal analysis methods. GdSrFeO4 is stable in the wide range of studied temperatures 40–1,400°C in air. The sintering start temperature was determined to be 985°C. GdSrFeO4 has a thermal expansion coefficient of 30 × 10−6 K−1. The thermal stability is excellent for further investigation and potential for application of the materials as SOFC, for example. The study of catalytic stability of the obtained GdSrFeO4 is to be a subject of future work as well.

The effect of hydrogel on one- and two-year-old saplings of English oak Quercus robur L.

Survival rate of English oak ( Quercus robur L.) saplings (one- and two-year-old) on experimental plots under different hydrological conditions (long-interval flooding, short-interval flooding, no flooding) and the effect of hydrogel on the survival of the planted stock were studied. At present, these studies are relevant for the floodplain forest ecosystem of the Volga River, since the forests of this region are experiencing huge natural and anthropogenic loads, therefore, developments are needed for their conservation and restoration. The purpose of the research was to study the method of planting English oak ( Qurcus rbur ) with annual and biennial saplings using hydrogel to restore and increase the biodiversity of degraded forest phytocenoses in conditions of the Volga-Akhtuba floodplain in the north of the Astrakhan region. In the work, the following methods were used: soil moisture was determined by the thermostatic-weight method (B.A. Dospekhov); experimental data were processed by the method of dispersion analysis using Microsoft Excel. According to the results of the study, the best survival rate (83 %) was observed in one-year-old saplings of English oak in the variant with using hydrogel in no-flooding site.

Эффективность использования разного уровня ферментированного рапсового шрота в рационах лактирующих коров в период раздоя

Purpose. Evaluation of the effectiveness of using different levels of fermented rapeseed meal in the diets of lactating cows during the milking period. Materials and Мethods. Scientific, economic and physiological experiments were carried out in the conditions of the farm of Delta-F LLC in the Sergiev Posad district of the Moscow region on three groups of Holstein cows: control, experimental 1 and 2. Cows from the control group were fed the main diet with the addition of 2.5 kg of traditional rapeseed meal, animals from experimental 1 additionally received 1.25 kg of natural rapeseed meal and 1.25 kg of fermented rapeseed meal, from experimental 2 – 2.5 kg of fermented rapeseed meal. The physiological experiment was carried out at the end of milking period, for which 3 heads were selected from each group. The amount of feed given and consumed was weighed daily. Sampling of feed, milk, preservation of feces and urine was carried out according to generally accepted methods. Data processing was carried out using specialized computer software using methods of dispersion and correlation analysis. Results. During the 92-day experiment, it was found that the animals of the experimental groups (1 and 2) were characterized by high parameters of gross and daily milk yield. The gross milk yield of natural and 4% fat milk was higher in cows of the 1st experimental group compared to the control group by 3.3 and 4.4% (P≤0.05), and the protein yield was by 5.1 kg (P≤0.05). The inclusion of different levels of fermented rapeseed meal in the diet had a positive effect on protein digestibility in animals of the experimental groups. The highest amount of digestible nitrogen, as well as nitrogen excreted in milk, was observed in cows of the 1st and 2nd experimental groups. Conclusion. The addition of fermented rapeseed meal (1.25 kg) into the diet of cows during the milking period and the content of non-cleavable protein at a level of at least 39.3% has a positive effect on animal productivity and milk quality.

Научное обоснование использования древесины осины в деревянных клееных конструкциях

One of the promising materials for construction are wooden glued structures. According to the current regulatory documents, for the production of such structures coniferous wood is usually used, the reserves of which in industrially developed areas have significantly decreased over the last decades. At the same time, in a number of regions of Russia there is a significant raw material reserve of aspen wood, which has been successfully used in the construction of buildings and structures for many centuries. Its physical and mechanical characteristics differ from pine wood from 3.2 to 18.6 %. Therefore, it can be considered as an alternative source of raw materials for wooden house construction enterprises. To assess the degree influence of the combination of coniferous and aspen wood on the strength of the glue joint, as one of the main indicators of the quality of wooden glued structures, a set of theoretical and experimental studies was carried out. Maximum tangential and normal stresses of glue joint in pine and aspen blanks, which are significantly higher than those of solid wood, were determined by calculation. The values of shear strength in glued pine and aspen lamellas (4.46–8.06 MPa), obtained during the experiments at the 1st stage of research, were close to the strength of solid wood. At the 2nd stage the method of dispersion analysis was used, the results confirmed the assumption that when gluing lamellas up to 20 mm thick, the difference in the strength of the glue joint of structures made of pine and structures made of pine and aspen is insignificant. The obtained data serve as a basis for further work on diversification of raw material resources in the production of wooden glued structures due to the involvement of low-demand aspen wood in processing. For citation: Titunin A.A., Gevorgyan M.S., Fedotov A.A., Vakhnina T.N., Susoeva I.V. Scientific Substantiation of Aspen Wood Use in Wooden Glued Structures. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 6, pp. 149–161. (In Russ.). https://doi.org/10.37482/0536-1036-2023-6-149-161

Estimation of wave velocity and analysis of dispersion characteristics based on wavelet decomposition

Due to the complexity of the crustal medium and stratigraphic boundaries, seismic waves typically exhibit attenuation and dispersion after propagation through the medium. By studying the regularity of seismic wave dispersion, soil layer information can be extracted. Current spectral decomposition techniques take less account of signal filtering processing of seismic waves, and the complexity of the stratigraphy tends to reduce the accuracy of dispersion analysis. Based on the above, a new method for calculating the dispersion characteristics of a site from surface and downhole ground vibration recordings is proposed, which is simpler than the spectra analysis of surface waves (SASW) method and eliminates the need for multiple pickups and additional equipment. This method is based on wavelet decomposition and seismic wave filtering, and a numerical simulation example is established to verify the effectiveness of the method. Then, the records of the Tohoku earthquake on March 11, 2011 are used as actual strong earthquake examples for filtering and dispersion analysis. Finally, it is concluded that the seismic wave dispersion analysis method based on wavelet decomposition can effectively filter and analyze seismic waves in specific frequency bands.

Study of the Structural, Morphological, Strength and Shielding Properties of CuBi2O4 Films Obtained by Electrochemical Synthesis.

In this research, the formation processes of CuBi2O4 films were examined using atomic force microscopy, energy dispersive analysis and X-ray diffraction analysis methods. The films were synthesized through electrochemical deposition from sulfuric acid solutions at a potential difference of 3.5 V. The duration of film growth was set to between 10 and 90 min to assess the possibility of controlled film growth and preserve the stability of their structural properties during growth over an extended period. An analysis of the data obtained by X-ray diffraction revealed that the resulting film samples are highly ordered structures with a tetragonal CuBi2O4 phase. The results of the connection between the thickness of CuBi2O4 films and strength properties depending on the time of film deposition were obtained. The results of the shielding efficiency of low-energy γ-quanta using CuBi2O4 films were obtained.

CONTROL INFORMATION OF STATISTICAL DATA BASED ON DISPERSION ANALYSIS

Problem statement. The accuracy and reliability of the source statistical material is the most important task of statistical observation. Even with a good organization of observations or conducting an experiment, for one reason or another, inaccuracies, errors, that is, registration errors, may appear. Analysis of the existing method of information control shows that it is too complicated, uses different criteria depending on the sample size, critical criteria values are selected from tables, calculation is performed using formulas and statistical functions of the Excel function master. The purpose of the article is to develop a method of information control based on dispersion analysis of observation data. Results. A single database of analogue objects is created. To correctly create a combined database, you need to be sure that the combined data belong to the same general population. The complexity of dispersion analysis depends on the size of the samples. If several samples of the same volume are combined, then it is easy to check their homogeneity with the help of the “One-factor dispersion analysis” tool, in the output of which the calculated and critical value F- Fisher's test - are given. The examples show that with the help of dispersion analysis it is possible not only to establish the homogeneity of samples, but also the reason for its violation. A method of dispersion analysis of the homogeneity of samples of different volumes was created using the “Descriptive statistics” tool of the analysis package. The adequacy check of the regression model of the active experiment was performed. The experiment plan determines the accuracy of the regression model. Some point is selected in the factor space and many points in its neighborhood are considered. An experiment is being conducted in this neighborhood, on the basis of which the first model is being built. The main requirement for the model is the ability to predict the direction of further experiments with the required accuracy. And the accuracy of this prediction in all search directions should be the same. A model that satisfies this requirement is called adequate. Checking the feasibility of this condition is called model adequacy analysis. In the process of conducting the experiment, it is necessary to make sure that the measured response values belong to the same general population and the technological process does not require regulation. For this purpose, is carried parallel experiments. After conducting 4 experiments according to the experiment planning matrix, it is necessary to make sure of the received response samples’ homogeneity and the reproducibility of the experiments. Conclusions. The performed calculations prove that: the existing method of information control is too complex and has significant disadvantages − different criteria are used depending on the sample size, critical values of the criteria are selected from tables, the calculation is performed using formulas and statistical functions of the Excel function master; the method of information control based on dispersion analysis does not have these disadvantages and is universal, because there is one criterion for small and large samples, the calculated and critical value of F-criterion are given in the initial information of the tool “One-factor dispersion analysis”, it can be used to create a single database analogue objects and to check the adequacy of the regression model at the active experiment.

A surface-wave seismic metamaterial filled with auxetic foam

Auxetic materials with negative Poisson's ratio (PR) exhibit superior mechanical properties with regard to energy absorption, while their potential for surface wave shielding is only in its beginnings. To attenuate surface waves in ultra-low frequencies (the starting frequency close to 0 Hz), which is the main scope of concern in seismic protection, this paper presents a novel type of seismic metamaterial (SM) with square pillars embedded as vibrators that is filled by auxetic foam. The designed SM is comprised of three commonly used construction materials, i.e., soil, concrete and auxetic foam. Combining the dispersive analysis and sound cone method, an ultra-low-frequency bandgap from 0 to 16.42 Hz is opened via the tensile resonance of the auxetic foam and the inverse dispersion effect. Furthermore, the parametric analysis further shows that filling material with a low Poisson ratio and low mass density is more favorable to widening the first complete bandgap (FCB), which means that foam is the ideal filling material for SM. The transmission spectra of the corresponding finite samples coincide well with the bandgap calculations. And the dynamic response of a scaled-down setup with a characteristic size of 1/10 of the original metamaterial is experimentally tested to validate the effectiveness of our study. We expect that this study prompts the engineering application of auxetic materials and ordinary building materials in seismic wave shielding at deep sub-wavelength frequencies.