Experimental-theoretical Method Research Articles

Photonuclear partial reaction cross sections: Systematic uncertainties and reliability

The well-known significant systematic disagreements between cross sections of partial photoneutron reactions (γ,1n) and (γ, 2n) obtained in various experiments majority of which have been carried out at Livermore (USA) and Saclay (France) were analyzed using the objective physical criteria of data reliability. It was found that experimental data for more than 50 nuclei from 51V to 209Bi in general do not meet those criteria and therefore are more or less unreliable. The experimental-theoretical method based on the Combined PhotoNuclear Reaction Model (CPNRM) was used to evaluate partial reaction cross sections that meet the reliability criteria. It was shown using the analysis in detail of differences between evaluated and experimental cross sections that the major sources of large systematic uncertainties in obtained cross sections are certain shortcomings of experimental neutron multiplicity sorting method have been used for indirect separation of partial reactions. It was shown that the newly evaluated cross sections of partial photoneutron reactions differ significantly (at least noticeably) from the ones obtained using the method of neutron multiplicity sorting but agree with experimental data obtained by alternative methods used for reliable direct separation of partial reactions. The consolidated review of many problems with partial photoneutron reaction experimental data reliability and some ways to solve ones are presented.

Experimental-Theoretical Method for Assessing the Stiffness and Adhesion of the Coating on a Spherical Substrate

Experimental-Theoretical Method for Assessing the Stiffness and Adhesion of the Coating on a Spherical Substrate

A calculation method for residual stress of cold expanded hole based on measured springback

Cold expansion can improve the fatigue life of bearing hole by introducing compressive residual stress. However, there is yet difficulty to measure the stress of hole wall because of the geometry and device limitations. In this study, a calculation method of residual stress based on the experimental-theoretical method is proposed by considering the circumferential symmetry of cold expansion. Stress and displacement are analyzed in the loading and unloading stages, and the measured springback is used in the unloading stage. The residual stress accuracy of the proposed method is significantly better than that of the classical elastic–plastic theory. Moreover, the effects of interference, expansion cycles and expansion speed on surface integrity and fatigue life are analyzed. It is found that interference is the most influencing parameter in coad expansion process, and there is a saturation effect of interference on improving the residual stress and fatigue life of bearing holes.

Cross sections of partial photoneutron reactions: the problems with reliability and new data

The (𝛾, 1𝑛), (𝛾, 2𝑛) and (𝛾, 3𝑛) reactions cross sections the majority of which were obtained using beams of quasimonoenergetic annihilation photons were discussed. The significant systematic uncertainties of the experimental results far exceeding the achieved statistical accuracy were considered. The results of experiments for about 50 nuclei from 51V to 209Bi were analyzed using objective physical criteria of data reliability. It was shown that in many cases the systematic uncertainties of experimental cross sections were significant and data do not satisfy physical criteria. The experimental theoretical method for evaluation of cross sections satisfying those criteria was described. The systematic uncertainties of several types due to shortcomings of the method of photoneutron multiplicity sorting used in experiments and specific features of neutron detectors used. The new evaluated reliable cross sections of the partial reactions and total photoneutron reaction (𝛾, 1𝑛)+(𝛾, 2𝑛)+(𝛾, 3𝑛) were presented.

Experimental and theoretical determination of the speed of sound in lung parenchyma of rabbits

The purpose of the study was to develop an experimental-theoretical method for determining the speed of sound in the lung parenchyma. The method is based on the measurement of the characteristics of the impedance of the Helmholtz resonator, that contains lungs under study. The input impedance of the Helmholtz resonator corresponds to the parallel connection of the lung impedance and a resonator. The modified two-microphone method is used to measure the resonant frequency and input impedance response of the product of the resonator chamber volume (lungs). The experimental system consisted of a loud speaker, a wave guide, two microphones for the measurement, and the end empedance node in the form of a connecting tube extended to the inside of the Helmholtz resonator with specified geometric characteristics. When the lungs are added to the Helmholtz resonator, the frequency increases, but not linearly with the decrease in their volume, indicating that the speed of sound is abnormal low in the lung parenchyma. The difference between the calculated and measured resonant frequencies is used to determine the speed of sound in the lung parenchyma. The measurements were carried out on air and collapsed lungs of 8 apparently healthy rabbits. Two variants of sound transmission in the lung parenchyma, corresponding to isothermal and adiabatic processes, are considered. The results of measurement and calculation demonstrate that the speed of sound in the lung parenchyma of an apparently healthy rabbit is 21-22 m/s, what is in accord with modern theoretical concepts.

QUALITY STUDIES OF PLASTIC PARTS OILFIELD EQUIPMENT

The article considers the quality of plastic parts of oilfield equipment depending on the modes of manufacturing their various designs and the composition of press materials. By adjusting the regime parameters in the manufacture of parts, quality indicators are determined: tensile strength, hardness of parts, and others. The use of parts made of plastic materials for the development of the oil field equipment industry can be considered efficient from a technical and economic point of view. Also, in order to improve the quality, strength and longevity, plastic masses, which are an alternative product to metals and non-metals, have started to be used. Studying the performance indicators of the used plastic materials is considered mandatory. The quality of details made of plastic masses depends on many factors, and the indicators of these factors appear during operation. The quality indicators of products made of plastic materials in oil field equipment are distinguished by the presence of unlimited possibilities, greater than structural materials. Parts made of such materials have high performance indicators and are used in the preparation of parts with different constructions using uncomplicated processing methods. For the development of the oil industry, ways to increase the durability and longevity of the equipment used in this industry should be investigated. Based on the results, an experimental-theoretical method for determining the main quality criteria (shrinkage deformation and other quality indicators, strength, hardness, surface roughness) of plastic parts is proposed. The developed technique for the design of plastic parts makes it possible to estimate the expected life of parts, taking into account their operating conditions. Keywords: quality, plastic parts, press materials, performance, shrinkage.

The study of calculation of equivalent stress of details in oil field equipment

The analysis of the specification of resistance of plastic details (thermosetting group, phenoplast, and aminoplastic with various fillers) and using the data on materials while manufacturing details of oil field equipment operated in conditions of Absheron region has been carried out. Based on the results, an experimental-theoretical method of definition of major criterion of quality (shrinkage strain, hardness, steadiness, surface roughness) of plastic details is offered. Developed technique in the structure of plastic details allows the estimation of predictable resource of details considering the conditions of their exploitation.

A novel experimental-theoretical method to improve MMP estimation using VIT technique

In the gas injection process for enhanced oil recovery (EOR), the interfacial tension (IFT) and the minimum miscibility pressure (MMP) are two key parameters for evaluating the miscibility condition. The vanishing interfacial tension (VIT) method is an efficient method for measuring the interfacial tension of oil and gas versus pressure and can estimate the minimum miscibility pressure. A problem in the VIT test of a hydrocarbon system is that during this test, oil and gas densities vary due to the composition variation of both phases. But in the conventional interfacial measurement, this issue is ignored, and the initial and non-equilibrium densities are utilized for estimating the interfacial tension. In this study, it is tried to nominate a novel method for estimating the most accurate value of IFT. Hence, for this purpose, first a VIT test has been performed for a hydrocarbon gas and a live oil system and using the axisymmetric drop shape analysis (ADSA), the oil droplet has been analyzed, and the geometry factor, which has been defined in this paper, was calculated. After that, the volume of oil droplet and the gas have been measured and were used for vapor-liquid-equilibrium (VLE) or flash calculation using Peng-Robinson equation of state (PR-EOS). By VLE calculation fulfillment, the final composition of two phases is determined. Eventually, the densities of two phases have been calculated for VIT modification. Finally, the IFT results were plotted versus the pressure steps, and the MMP were estimated. Furthermore, to evaluate the results of VIT test and its modification, slim tube displacement (STD) test, which is known as the most reliable laboratory method for measuring the MMP in the oil industry, has been performed. The results show that the values obtained for MMP values for the VIT test with the corrected densities which are lower than the values obtained for the VIT test for not-corrected densities and the suggested experimental-theoretical method has been estimated the MMP more accurately. The MMP obtained by VIT test and modified VIT method was equal to 3858.72 and 3722.0 psi, respectively. Meanwhile, the slim tube test has measured the MMP equal to 3667.13 psi.

Four-Carbon Segmented Discrete Hydrocracking of Long-Chain Paraffins in MTT Channels Following a Pore-Mouth Mechanism

Hydrocracking of long-chain paraffins is a key process in petroleum refining. A fundamental understanding of the reaction on the bifunctional catalyst is of great importance for controllable cracking. In this work, a mechanism study on the hydrocracking of long-chain paraffins catalyzed by Pt/ZSM-23 has been carried out. The distribution and accessibility of acid sites on MTT channels are purposefully adjusted. Based on reasonable simplification, the reaction data are analyzed to reveal the shape selectivity, reaction path, and catalytic mechanism. The applicability of the pore-mouth mechanism in this system has been carefully verified by experiments. Both protonated cyclopropane (PCP) and β-scission paths occurred simultaneously at the pore mouths, accounting for 60 and 40%, respectively. The proportions of PCP and β-scission paths with different chain lengths inserted in the pore are quantitatively calculated, which are multimodal. Shape selectivity of the teardrop-shaped MTT skeletal structure is investigated by the joint experimental–theoretical method. The insertion of the paraffin chain in the MTT channel is discretely segmented by integral multiples of four sequential carbon atoms starting at one end of the chain, which is followed by cracking through the mixed PCP and β-scission paths at pore mouths.

Метод определения дальности действия береговой радиолокационной станции

The paper considers an experimental-theoretical method for testing a coastal radar station using a test target with a reduced effective scattering surface (ESR), which makes it possible to take into account the effect of precipitation of varying intensity when testing in conditions of lack of precipitation. The limitations are considered when choosing the ESR of a test target both along the upper limit, due to the technical parameters of the tested radar and the range of the radio horizon, and along the lower limit, due to sea waves and reflections from the sea surface.

Experimental-theoretical method for studying the vehicle airbag modules functioning

Introduction (problem statement and relevance). The airbag belongs to the passive vehicle safety system (SRS - Supplementary Restraint System) and is the most important (together with the seat belt) restraint system that protects the driver and passengers in a collision with static or moving objects. The main task of the SRS is to minimize injuries to the driver and passengers and reduce deaths in various road traffic accidents. For the development and testing of modern high-tech airbag modules, it is necessary to have informative theoretical and experimental methods for studying the non-stationary processes of their functioning.The purpose of the study was to develop an experimental-theoretical research method based on modern highly informative tools of experimental physics of fast processes and numerical methods for continuous media dynamics.Methodology and research methods. To study the functioning dynamics of vehicle airbag modules, an experimental method for determining the kinematic and acoustic parameters has been developed and implemented, and a mathematical model of an airbag functioning process has been formulated and implemented in the LS-DYNA environment with the help of corpuscular particles method.Scientific novelty and results. The created experimental-theoretical method allowed both to simulate the functioning processes of the developed and tested airbag modules, and to carry out field tests of these modules. In addition, the experiment made it possible to carry out a detailed verification of the numerical method for calculating the airbag operation, on the basis of which it was also possible to perform numerical calculations interaction of the airbag and an anthropometric dummy model.Practical significance. The developed method for studying the processes of airbag modules functioning is an important and necessary component of creating a scientific, technical and experimental base for the development and production of passive safety systems.

Investigation of the influence of the nature of surface deformation on coating adhesion

The effect of deformation of the surface of a supporting metal element on the adhesion of a thin polymer film has been studied by an experimental-theoretical method. A setup has been developed that allows testing of adhesive coatings at various deformations of the substrate surface of various materials. The adhesion properties of a polymer film to a metal substrate have been determined. An explanation of the results obtained is given.

Estimation of electric loads dynamics in the gas fields of Western Siberia taking into account the life cycle of the fields

All gas fields go through four periods of their life cycle with their technological scheme changes. The engineering of electricity supply system for gas fields in West Siberia was performed without taking into account the final stage of their life cycle. To extend the period of profitability of low-pressure Cenomanian gas at the final stage of the life cycle an energy-intensive technology of gas compression distribution with usage of mobile compressor units (MCU) is implemented. The implementation of this technology in the gas fields requires the construction of a new electricity supply system or the reconstruction of the entire existing one. The objective of the paper is to assess the dynamics of electric loads of gas fields, considering the entire life cycle. The average annual calculated electric load for each life cycle period for active fields in West Siberia for 2019 is determined. The coefficient of increase in electric load is calculated. The tasks are solved using the empirical method (measurement, comparison) and the experimental-theoretical method (analysis and synthesis). The analysis shows that during the life cycle of a gas field, when the well outcrop and average reservoir pressure decrease over time, the calculated electrical load increases in many times.

Load distribution factor along the power transmission lines as a factor in choosing a voltage class

Gas fields differ from industrial enterprises by long power transmission lines with low electrical loads (low density), which grow many times during the life cycle. Power supply to gas well clusters is carried out according to the scheme - “main circuit with one through line with transformer substations distributed along the line”. The distribution of transformer substations along the transmission line affects the voltage loss, and, consequently, the choice of voltage class. The purpose of the research is to quantify the distribution of transformer substations along the power line to develop a mathematical model for calculating the optimal voltage class. To achieve this goal, the following tasks are solved: five power supply schemes are built for gas well clusters; electric moments are calculated for each scheme; the load distribution coefficient is determined. The problems were solved using an experimental-theoretical method (analysis and synthesis) and a software product – Mathcad. As a result, the coefficient is calculated in the work - for even load distribution, when placing the entire load at the end of the line and when placing the load at the beginning of the line.

STUDY OF THE HEAT-CARRYING FLUID TEMPERATURE INFLUENCE IN THE HEAT SUPPLY SYSTEM ON THE INDOOR AIR TEMPERATURE

This article presents a brief history of the country’s heat supply system development. The types of heat supply systems are considered, their brief characteristics are given. Methods for determining the heat load for household needs (heating and hot water supply) of urban residents are presented. The study of the coolant temperature influence on the air temperature in the room was carried out. The study used an experimental-theoretical research method. As a part of the experimental study, the data of temperature measurements in one of the heating points in Tyumen were requested. Within the framework of a theoretical study, the air temperature in a living room was calculated, depending on the coolant temperature according to the schedule of the CHPP and according to the supply in the supply heat pipe. In carrying out the theoretical study, standard methods were used for carrying out thermal calculations of heat supply systems, statistical research methods, as well as standard computer programs. The need to regulate heat energy is determined and the types of regulation are considered. The analysis of the adopted temperature schedule of the CHPP was carried out and a comparison was made with the calculated temperature schedule. The solution of the equation for determining the air temperature in the room is given. The air temperature in the room depends simultaneously on two factors: the temperature of the heating medium and the temperature of the outside air. As a result of the study, the presence of a discrepancy between the temperatures of the network water supplied to consumers and the created air temperature in residential premises was determined. The intersection point of the calculated temperature schedule and the CHP schedule was determined. The necessity of observing the calculated temperature schedule of the central quality regulation has been substantiated. The necessity of heat supply at a constant flow rate of the heat carrier has also been substantiated.

EXPERIMENTAL-THEORETICAL METHOD OF DETERMINING THE FRICTION COEFFICIENT DURING THE MOTION OF THE SOIL IN A CYLINDRICAL PIPE WITH A HORIZONTAL DEVELOPMENTS

Purpose. The aim of the work is to develop an experimental-theoretical method for determining the coefficient of friction when soil moves in a cylindrical pipe, which in modern construction conditions must be known in theoretical studies to assess the magnitude of pressure, soil density and other factors when laying utility lines in a closed way. Methodology. Based on the analysis of modern methods and methods of force impact on the soil mass and mechanical and technological processes that occur in the soil mass when laying engineering communications using the static puncture method and the punching method. To develop and describe an experimental-theoretical method for determining the coefficient of friction during soil movement in a cylindrical pipe, which must be determined in theoretical studies to assess the magnitude of pressure, soil density and other factors. To formulate the main tasks that need to be solved in the future and establish the criteria for their use for the study of mechanical processes when performing horizontal workings by compaction of the soil mass. Findings. The analysis of domestic and foreign scientific and technical sources on the laying of engineering communications by a closed method is carried out. In particular, an experimental-theoretical method for determining the coefficient of friction when soil moves in a cylindrical pipe has been developed and described, which must be determined in theoretical studies to assess the magnitude of pressure, soil density and other factors when laying utility lines in a closed way. The main tasks that need to be solved in the future are formulated and the criteria for their use for the study of mechanical processes when performing horizontal workings by compaction of the soil mass are formulated. It is also necessary to solve the problem of the non-stationary equation of soil motion, taking into account the coefficient of friction to the outer surface of the pipe. Scientific originality. In this work, based on the analysis of scientific and technical sources of force impact on a continuous soil massif, established information about the processes in the soil massif during excavation by the static puncture method and the punching method. In particular, the basic dynamic properties of soils have been established and theoretical foundations have been formulated for the study of mechanical processes during horizontal workings by compaction of a soil massif. Practical value. On the basis of these data, it was possible to develop an experimental-theoretical method for determining the coefficient of friction when soil moves in a cylindrical pipe, in particular, when laying pipes using a closed punching method. This coefficient must be known to assess the magnitude of pressure, soil density and soil plasticity zone and other factors.

Mathematical modeling in the problems of the geodesic control of the stressed-formated state of the gas pipelines at above-ground parts

Geodetic methods of monitoring the stress-strain state of gas pipelines in the areas of overhead pipeline crossing involve obtaining discrete data on the deformation of its axis in the form of a set of three coordinates (x, y, z). For their elaboration a mathematical model of the experimental-theoretical method of geodetic control of gas pipelines’ SSS is proposed. The simulation process was performed on the basis of geodetic discrete data, based on which, using the Lagrange interpolation polynomial, the equation of the line of bending of the axis of the gas pipeline was obtained, which allowed to pass further to the bending moments along the entire span. The accuracy of the proposed method has been estimated, which showed that the obtained bending moment diagrams reflect the SSS of gas pipelines with an accuracy of 1.5% in the central part of its span, and with the approach to the peripheral sections the error increases to 6%. It is shown that the obtained expression of the maximum bending moment allows us to form the required number of additional equations for the disclosure of a statically indeterminate system of "gas pipeline-support", taking into account the possibility of fastening on stretch marks. The mathematical model is presented aimed at decomposition of overburden gas pipeline structures, which allows to model the SSS at each of the spans separately within the integral structure.. It is established that additional stretch marks reduce the maximum bending stress by 22%, and in case of loss of one of the stretches of the bearing capacity of the gas pipeline SSS increases by 11.1-14.8% depending on the previous stretch tension. The proposed mathematical model for the processing of discrete data forms the basis of the experimental-theoretical method of geodetic control of the gas pipelines’ SSS, taking into account their structural and technological factors.

New 209Bi photodisintegration data and physical criteria of data reliability

The well-known problem of noticeable disagreements between photoneutron cross sections from various experiments was discussed in detail for 209Bi. Data for partial photoneutron reactions cross sections obtained at Livermore (USA) using quasimonoenergetic annihilation photons and the method of neutron multiplicity sorting were analyzed using the objective physical criteria and the experimental-theoretical method for evaluation. Because of significant systematic uncertainties involved in the method for determining the neutron multiplicity, experimental data do not satisfy the criteria of reliability and differ noticeably from the evaluated data. The new experimental data for 209Bi (γ, in) reactions with i = 1–4 were obtained using quasimonochromatic laser Compton-scattering (LCS) γ-ray beams at the NewSUBARU synchrotron radiation facility and the novel technique of direct neutron-multiplicity sorting with a flat-efficiency detector. It was found that new σ(γ, 1n), σ (γ, 2n), and σ (γ, 3n) contradict noticeably to the Livermore data. It was shown that at the same time the new 209Bi photoneutron cross-sections are in good agreement with data evaluated using experimental-theoretical method and assuring the reliability of those.

ЭКСПЕРИМЕНТАЛЬНО-ТЕОРЕТИЧЕСКИЙ МЕТОД НАХОЖДЕНИЯ УПРУГИХ МОДУЛЕЙ РЕЗИНОПОДОБНЫХ МАТЕРИАЛОВ НА БАЗЕ АКУСТИЧЕСКОЙ СИСТЕМЫ VERASONICS

The experimental-theoretical method for determining the elastic characteristics of rubber-like materials is presented. This method is founded on the technology SWEI (Shear Wave Elasticity Imaging) with using the open architecture Verasonics speaker system that implements a method for generating and measuring shear wave velocity in rubbery media. The SWEI method makes it possible to measure the shear wave velocity (and, accordingly, elastic characteristics: Young's and shear modules) in soft biological tissues and finds application in medical diagnostics – shear wave elastography. The results of measuring the elastic characteristics of rubber-like media are presented. For physical modeling, polymer CIRS phantoms (Model 049 Elasticity QA Phantom Spherical) were used as measurement media. Young's modules of different types of polymer calibrated phantom measured on the Verasonics acoustic system are comparable with the tabular values. Numerical modeling of the evolution of shear waves in rubber-like media is carried out. Numerical analysis was performed using the k-Wave programming package. This programming package is based on k-space transition, where spatial gradients are computed using a Fast Fourier Transform scheme and temporal gradients are computed using a corrected k-space difference scheme. The k-Wave programming package combines the optimization of the MATLAB programming environment for working with matrix operations and a set of tools that allows you to simulate an ideal (non-dissipation) propagation environment using parameters such as density and sound velocity for a given rubber-like material. The combination of these factors allows you to model 2D and 3D spaces while maintaining high computational speed. For polymer CIRS phantoms, the results of physical and numerical modeling are compared to determine the elastic characteristics of rubber-like media.

Photodisintegration of <sup>127</sup>I: Systematic Uncertainties of Experiments and Data Evaluated Using Physical Criteria

The experimental data for photoneutron reaction cross sections for 127I obtained using beams of quasimonoenergetic annihilation photons and the method of neutron multiplicity-sorting at Livermore (USA) and Saclay (France) were analyzed using objective physical data reliability criteria. It was found that data of both laboratories contain significant systematic uncertainties and therefore are not reliable. New data for partial and total photoneutron reactions cross sections for 127I satisfied physical criteria of data reliability were evaluated using experimental-theoretical method based on both experimental neutron yield reaction cross-section and results of calculation in the combined photonucleon reaction model (CPNRM). The neutron yield reaction cross-section obtained at Saclay (France) was used in evaluation procedure. The newly evaluated cross sections for partial (γ, 1n), (γ, 2n) and (γ, 3n) reactions for 127I were used for discussion in detail the problems of significant disagreements between experimental data for many nuclei obtained at Saclay and Livermore. It was found that systematic uncertainties of experimental data for the (γ, 1n), (γ, 2n), and (γ, 3n) reactions cross sections for 127I obtained at both laboratories are of different nature. One of the reasons of noticeable systematic uncertainties of cross sections obtained are the shortcomings of the procedures used to separate counts into 1n, 2n, and 3n events. At the same time it was shown that the main reason of significant disagreements between new evaluated data and data obtained at Livermore experiment for 127I is the loss of many neutrons from the (γ, 1n) reaction. This situation is analogous to those in Livermore experiments for 75As and 181Ta.