Physical Experimental Methods Research Articles

Method for Measuring Interface Pressure of High-Voltage Cables

In high-voltage cables, because of the close fit of their internal structures, interface pressure is generated between conductor and insulator, which affects the performance of the cable. Studies on the calculation and testing of the interfacial pressure of cable conductors are scarce because of the lack of a unified formula and the difficulty of direct measurement. As such, in this study, we devised two methods for calculating and measuring the interface pressure of cable conductors. In the first, we used two physical experimental methods. We used the friction between cable components to perform the calculation and create an experimental method for determining cable conductor interface pressure; on the basis of the equation of the pressure inside and outside a thick-walled cylinder using elasticity mechanics, we calculated the interface pressure on the basis of the measurement of the strain state of the inner and outer diameters of each layer of the cable under different assembly and stripping conditions. We verified the effectiveness of the methods through physical tests and simulations using a YJLW03 1 × 1200 high-voltage cable. Then, we used simulation software ANSYS and SolidWorks to calculate the interface pressure. With different simulation settings, we obtained results regarding interface pressure. Lastly, these simulated values were individually compared with two physical tests, and the error was calculated. Results obtained in the ANSYS environment showed that interface pressure values determined by the geometric interference normal stress, geometric interference pressure, contact interference normal stress, and contact interference pressure methods were 39.75, 36.84, 5.76, and 36.57 MPa, respectively. In SolidWorks software, we used the contact-stress and X-axis normal stress methods. Results were all 37.36 MPa. Then, simulation results and experimental results were compared, and error was calculated. The comparison showed that the X-axis orthogonal stress method was the most accurate. Errors between the X-axis orthogonal stress method and the two physical experiments were 1.5% and 0.48%. Through the above simulation and physical experiments, we determined the interface pressure between conductors and insulators in a high-voltage power cable. We obtained the cable interface pressure value through two kinds of physical experiments, and these two methods were clearly reliable. Simulation experiments showed that using SolidWorks software to simulate this problem obtained better results. Research results provide technical support and reference for the calculation and measurement of cable interface pressure and the optimization of cable performance.

Recent Progress in Research of Metal Melt Structure

This article reviews the research methods and research progress of metal melt structures at home and abroad in recent years. Through liquid XRD, synchrotron radiation X-ray diffraction experiments, X-ray fine structure absorption spectroscopy, sensitive physical property testing and other experimental methods, as well as computer simulations, a lot of information about the structure of metal melts has been obtained. These studies are liquid-solid The structural transformation, the improvement of alloy structure and performance, and the preparation of amorphous provide theoretical guidance.

Magnetic Nanoparticles in Medicine: Progress, Problems, and Advances

The review presents an analysis of the current state of research related to the design, development, and practical application of methods for biomedical radioelectronics and nanomedicine, including the use of magnetic nanoparticles. The important role of rational scientific physical approaches and experimental methods in the design of efficient and safe magnetic nanoparticle-based agents for therapy, controlled targeted drug delivery, and diagnostics, including spatial imaging, is emphasized. Examples of successful practical application of magnetic nanoparticles in medicine based on these methods are given, and an analysis of the main problems and prospects of this area of science is conducted.

Moving Quick Response Codes Identification: System Performance Analysis and Maximization by Optimization of Illuminance and Exposure Time

We studied the relationship of Quick Response (QR) code identification system performances with illuminance on the QR code, exposure time of the camera, and relative moving speed. We studied the root causes of low identification performance problems on moving QR code as well. A physical experiment method study on a minimal working example of a real-time moving QR codes identification system with ZBar QR codes identification algorithm has done, and then the results were quantitatively and qualitatively analyzed. The values of illuminance on the QR code, exposure time of the camera, and relative moving speed used in the experiments were 140 lux - 640 lux, 0.7 ms - 22.2 ms, and 0 m/s - 2.5 m/s, respectively. Our data boundaries of the experiment results regarding exposure and motion blur (mediator variables) were respectively 0.108 lux·s - 12.476 lux·s and 0.0 pixel - 30.4 pixel. We identified physical phenomena in imaging, exposure and motion blur, could make the QR code image too dark/too bright and motion blurred. Such phenomena could make the QR code hard to identify and being the root cause of the problems. Our quantitative study proved that identification system performance is affected by illuminance, exposure time, and relative moving speed. Finally, we proposed a novel solution to overcome the problems by using a numerical method to compute the optimal illuminance on the QR code and the camera's exposure time for the given relative moving speed of the system.

ПОИСК ПУТЕЙ ПОВЫШЕНИЯ ТЯГОВЫХ СВОЙСТВ ТЕПЛОВОЗОВ И КОНСТРУКЦИЯ ТЯГОВОГО ПРИВОДА

The work objective is to increase the traction properties of locomotives without the use of traction drives with asynchronous traction motors and pulse width modulation.
 Research methods: methods of physical and field experiments, analytical methods for calculating the dynamics of the rolling stock.
 Conclusion: based on the conducted research, it is proposed to perform a promising diesel locomotive in the form of two sections on three two-axle bogies and a booster on two two-axle bogies, as well as to carry out experimental design work to develop an arc-type stator asynchronous motor and traction drives of a diesel locomotive using it.

3D reconstruction of digital cores based on a model using generative adversarial networks and variational auto-encoders

The digitalization of cores, namely the reconstruction of digital cores, is a method to reflect the real internal structures of cores by reconstructing the microstructural information and describing the microstructure of cores on the pore scale, which has become an effective way of quantitatively analyzing the pore structures and other matters in cores for rock physics and petroleum science. The modeling method of digital cores can be divided into the physical experimental methods and numerical simulation methods. Physical experimental methods usually are time-consuming and expensive because the drilling and core sampling for physical experiments are quite costly and the manufacturing of experimental samples sometimes are difficult to implement. Without the complex physical preparation and the demands for expensive equipment, numerical simulation methods are relatively cost-effective but still suffer from a lengthy processing time. Recently, deep learning and its variants can effectively extract characteristics from training images (TIs), casting light on the fast reconstruction of digital cores. In this paper, a reconstruction method is proposed by combining the variational auto-encoder (VAE) and the generative adversarial network (GAN) to achieve the balance of their strengths and weaknesses. Besides, the learning diverse generations using determinantal point processes (GDPP) is added to improve the quality of the generated results. Compared to some numerical simulation methods and GAN, the effectiveness and practicability of the proposed method are demonstrated. • The reconstruction quality by our method is better than GAN. • Our method can save and reuse model parameters for other reconstructions. • Our method is suitable for large-quantity reconstructions.

ПОИСК РАЦИОНАЛЬНЫХ ТЕХНИЧЕСКИХ РЕШЕНИЙ ТЕПЛОВОЗА ДЛЯ ВОСТОЧНОГО ПОЛИГОНА

The purpose of the study is to search for rational engineering solutions for the main autonomous locomotive for the Eastern range of OAO Russian Railways.
 Research methods: methods of physical and field experiments, analytical methods for calculating the dynamics of the rolling stock. 
 Research results and novelty: it is established that the use of a four-axle truck of a diesel locomotive TEM7 does not allow to create a locomotive that meets all the requirements of OAO Russian Railways, and the design of truck TEM7 is irrational for mainline locomotives; it is proved that the one-sided arrangement of brake blocks leads to deterioration in the locomotive braking properties. The bearing and axial towline, despite the use of an asynchronous engine, has an unsprung mass 1.5 times greater than that of the previously produced domestic analogue with a collector engine and almost the same mass of the wheel-motor unit; dynamic moments in the drive due to the lack of elastic elements during prolonged operation can reach 56% of the traction torque, which worsens the traction properties of the locomotive. 
 Conclusion: it is advisable to carry out a design study of the drive variant with a support-frame asynchronous traction engine and an axial gearbox, as well as to conduct a technical and economic analysis and design study of a cheaper version of a diesel locomotive with sections on three two-axle bogies, maximally unified with electric locomotives, with a booster tanker module and AC-DC transmission with axial regulation of eight-pole collector motors with support-frame suspension.

Optimization of Ultrasonic Elliptical Vibration Cutting Parameters Based on Response Surface Method

Background: Problems, such as severe hardening and poor processing quality, are present in the cutting process of difficult-to-machine materials. Objective: The aim of this study was to investigate and optimize the machining parameters of 630 stainless steel by using an independently designed 28-KHz double-excitation elliptical vibration cutting process. Methods: Using the AdvantEdge platform and response surface method, the effects of the cutting speed v, feed rate f, and cutting depth ap on the cutting forces Fx and Fy in the feed and depth directions, respectively, and cutting temperature T were analyzed. Then, regression prediction models with three response variables for each of the three independent variables were established, and the best cutting parameter combination was optimized. Finally, the results were obtained and validated through physical experiment methods. Results: Results show that the error of the experimental results relative to the predicted ones under the optimized cutting parameter combination is less than 9%. Conclusion: Based on the response surface method, the optimal cutting parameters are obtained, and the cutting force and cutting temperature are at a lower level. The findings indicate the feasibility of the optimized machining parameters and provide a reference for the selection of cutting parameters and the publishing of patents, and when ultrasonic vibration is used, for cutting difficult-to-machine materials.

Comparative Study on Computer Simulation of Solar Shading Performance with Heliodon and Artificial Sky

Current technological advancement and the requirement for sustainability-driven practices has birthed increased demands for accuracy in performance and assessment of energy consumption in the built environment. Energy-efficient and sustainable building projects are to large extents dependent on achieving functional solar shading and sufficient daylighting in building interiors. Hence, the understanding and adequate evaluation of the sun and its dynamic influence on buildings right at the early stage of planning and design is essential for the development of performance-driven building designs. In this study, the performance simulation results of Integrated Environmental Solutions <Virtual Environment> software program modules are examined for accuracy in executing performance analysis of solar shading. This study assesses the shading prediction of Suncast; a virtual solar shading calculation tool, and RadianceIES for measuring daylight availability in a tropical climate region. The evaluation of shading performance with Suncast was validated through physical experiment by comparing the results obtained therein with shading analysis outcomes generated on a scale model with the aid of a heliodon. Likewise, RadianceIES daylighting simulations were compared with measurements realised from an artificial sky simulator. The results were further subjected to correlation tests to determine the relationship between simulation and physical experiment results. The computational evaluation approach presented more efficient means of conducting the performance simulations over the physical experiment methods which were limited by mechanical design of the components. Suncast and RadianceIES simulation results presented comparable equivalence with measurement output acquired from the heliodon and artificial sky respectively, with minimal variations in accuracy. Thus, demonstrating the ability of the computational simulation program in accurately predicting solar shading and daylight performance in buildings, this could benefit architects in the proper and efficient design of shading devices for building facades at early design stages.

Theoretical Study on Quantitative Characterization of Interlayer Interference in Multi-Layer Commingled Production

X oilfield is a typical layered reservoir with a large vertical span and many oil-bearing formations. There are significant differences in reservoir types and fluid properties among various formations. The interlayer interference is severe in the development process. At present, the interlayer interference research based on dynamic monitoring data cannot meet development adjustment needs. Combined with the field test results, through the indoor physical simulation experiment method, dynamic inversion method, and reservoir engineering method, this paper analyzes the main control factors and interference mechanism of interlayer interference, studies the variation law of interference coefficient, improves and forms the quantitative characteristic Theory of interlayer interference in multi-layer commingled production, and provides theoretical guidance for the total adjustment of the middle strata division in the oilfield.

Preventive Control Policy Construction in Active Distribution Network of Cyber-Physical System with Reinforcement Learning

Once an active distribution network of a cyber-physical system is in alert state, it is vulnerable to cross-domain cascading failures. It is necessary to transit the state of an active distribution network of cyber-physical system from an alert state to a normal state using a preventive control policy against cross-domain cascading failures. In fact, it is difficult to construct and analyze a preventive control policy via theoretical analysis methods or physical experimental methods. The theoretical analysis methods may not be accurate due to approximated models, and the physical experimental methods are expensive and time consuming for building prototypes. This paper presents a preventive control policy construction method based on a deep deterministic policy gradient idea (shorted as PCMD) to generate and optimize a preventive control policy with Artificial Intelligence (AI) technologies. It adopts the reinforcement learning technique to make full use of the available historical data to overcome the problems of high cost and low accuracy. Firstly, a preventive control model is designed based on the finite automaton theory, which can guide the data collection and learning policy selection. The control model considers the voltage stability, frequency stability, current overload prevention, and the control cost reduction as a feedback variable, without the specific power flow equations and differential equations. Then, after enough training, a local optimal preventive control policy can be constructed under the comparability condition among a fitted action-value function and a fitted policy function. The constructed preventive control policy contains some control actions to achieve a low cost and in accord with the principle of shortening a cross-domain cascading failures propagation sequence as far as possible. The PCMD is more flexible and closer to reality than the theoretical analysis methods and has a lower cost than the physical experimental methods. To evaluate the performance of the proposed method, an experimental case study, China Electric Power Research-Cyber-Physical System (shorted as CEPR-CPS), which comes from China Electric Power Research Institute, is carried out. The result shows that the effectiveness of preventive control policy construction with the PCMD is better than most current methods, such as the multi-agent method in terms of reducing the number of failure nodes and avoiding the state space explosion.

Ground simulation research on the super large moment of inertia of the space transfer manipulator

During the construction of the space station, the cabin is driven by the transposition manipulator in space. Because of the large mass and volume of the cabin, which is not less than 22 tons, there will be emerge a large moment of inertia in the transposition process, which is not less than . Therefore, a full physical experimental method is designed to simulate the moment of inertia of the transposition manipulator in space on the ground. In this paper, the three-dimensional model of the whole physical loading method is built, and the dynamic model is built by using the Lagrange equilibrium method. The minimum values of the moment of inertia applied by this method to the shoulder joint and the wrist joint of the space manipulator are calculated as and respectively. The simulation through Adams show that the error of the method to the shoulder joint and the wrist joint of the manipulator is increased by 4.4% and 5.59% respectively compared with that of the dynamics, that is to say no matter in numerical value or error, all physical experiment methods meet the requirements of ground test.

The Charm of Small Conferences

AbstractNo abstract.

Thermal effects investigation during biomass slow pyrolysis in a fixed bed reactor

The desire to increase the role of renewable biomass resources in the energy sector sets the task of finding promising areas for its resource-efficient use. Pyrolytic conversion (pyrolysis) of biomass can be considered as one of such directions. The efficiency of pyrolysis depends on the possibility of its implementation in the autothermal mode. In this regard, the purpose of this work is to study the thermal conversion of biomass in the process of slow low-temperature pyrolysis in relation to its implementation in a fixed bed reactor. Physical experiment methods, differential thermal analysis and electron scanning microscopy were used in the work. As a result of the study, it was shown that in the process of straw and peat low-temperature pyrolysis (heating rate of 10 °C/min) a thermal exothermic decomposition effect was observed when the reactor was heated to 500 °C. This effect led to an increase in the rate of heating of the biomass bed. Moreover, in the case of straw pyrolysis, the temperature in the bed began to exceed the temperature of the reactor wall (up to 55–60 °C) when heated above 303 °C. The total values of the exothermic effect of straw and peat pyrolysis in the temperature range of 170–600 °C were 1,475 kJ/kg and 862 kJ/kg, respectively (based on the dry mass of the feedstock). The scanning microscopy method shows the change in the biomass structure during the pyrolytic decomposition process.

Laboratory study heterogeneity impact on microscopic residual oil distribution in tight sandstone cores during CO2 immiscible flooding

ABSTRACTWe use physical simulation experiment and nuclear magnetic resonance methods to investigate crude oil distribution after immiscible CO2 flooding schemes in tight sandstone cores. Experimental results indicate that water-wet cores lead to the highest final recovery factor in comparison with intermediate wet cores and weak oil-wet cores, and the recovery oil difference in clay micropore is mainly because of the heterogeneity, and the difference in medium pore and large pore is affected by asphaltene precipitation phenomenon. Therefore, it is important to enhance the recovery in the clay micropores and reduce the impact of cores permeability reduction caused by asphaltene precipitation. Based on this investigation on the residual oil saturation in pore throats, immiscible CO2 flooding can be a potential method to improve recovery efficiency in tight oil reservoir.

Influence of initial oxidation and secondary oxidation on spontaneous combustion of lignite

In order to prevent the re-ignition of residual coal, this study presents a study of initial oxidation and secondary oxidation on the spontaneous combustion characteristics of coal. Three physical experiment methods:pore volume analysis, Fourier transform infrared spectroscopy and cross point temperature method, were used to study the spontaneous combustion of lignite. The results show that the pore volume of coal increases with the increase of oxidation temperature. With the increase of temperature, different functional groups in the coal sample show different trends. Compared with initial oxidation, the tendency of the functional group changes again during the secondary oxidation. In the case of constant initial temperature of secondary oxidation, the crossing point temperature of coal samples show a decreasing trend at first and rising later. And in the case of constant initial temperature of initial oxidation, the crossing point temperature of coal samples show a trend of rising.

Change of water saturation in tight sandstone gas reservoirs near wellbores

Tight sandstone gas reservoirs commonly contain water, so liquid loading often appears near wellbores, leading to production decline and even shutdown of gas wells. Therefore, the study on the change of water saturation near wellbores is of great significance to understanding the water production mechanisms of gas wells. In this paper, a set of physical simulation experiment procedures of identifying the change of water saturation near wellbores was designed according to the principle of radial well seepage of gas wells, and the production performance after vertical well fracturing in gas reservoirs was simulated by connecting tight cores with a diameter of 10.5 cm, 3.8 cm and 2.5 cm in series in a descending order of distance. According to the depressurizing production mode of gas wells, tubes with small diameters of 20, 30, 40 and 50 μm were used to simulate gas well tubing to control the gas production rate. And the change of water saturation near wellbore in the process of depletion production and its influencing factors were investigated. Finally, combined with actual data of production wells, the water saturation and water production of gas wells near wellbores and in different zones were calculated at the above four different small diameters of tubes and the changes thereof were also analyzed. The following results were obtained. First, each gas production rate corresponds to a critical water saturation. When the initial water saturation is lower than the critical value, the formation water flowing near the wellbore and in the middle zone can be carried out along with the production of gas and no liquid loading is formed. Second, when the initial water saturation is higher than the critical value, a large amount of formation water migrating from the far-wellbore zones accumulates near the wellbore, and thus liquid loading occurs at the bottom hole. Third, when the initial water saturation is equal to the critical value, the higher the gas production rate is, the more easily liquid loading tends to form near the wellbore. Fourth, for the same water saturation, water production increases and recovery factor decreases with the increase of gas production rate. In conclusion, the cumulative water production chart of a gas well generated by the physical simulation experiment method proposed in this paper agrees well with the water production behavior of the corresponding gas well. The research results are conducive to the effective prediction of gas well water production and can be used as guidance for the reasonable gas well water control.

Experimental and numerical simulation on the influence of anisotropic fracture network deformation to shale gas percolation

Shale gas reservoirs usually have extremely low porosity and permeability. By massive fracturing, shale gas industry development has well-developed fracture network, which generally has the characteristics of anisotropy and pressure sensitivity. Present studies on fracture network fail to consider both anisotropy and pressure sensitivity. The percolation experiments on pressure sensitivity, gas slippage effect, and water damage mechanism are carried out by a new physical experiment method with similar materials. It is not only more convenient but also more secure to use similar materials to observe fracture deformation and the flow law of fluid under low pressure. Then a new percolation mathematical model considering both anisotropy and pressure sensitivity is established. And a numerical solution of mathematical model with 19-point fully implicit finite difference is conducted. Finally, a discussion is presented of the results of numerical simulation and experiment test. The most significant finding is that (a) the gas slip effect has a greater influence on gas apparent permeability of fracture network media than pressure-sensitivity effect does; (b) the gas apparent permeability of fracture network media was affected greatly by fracturing fluid due to the formation damage and relative permeability; (c) the permeability of fracture network increases with initial formation pressure increases, decreases with well bottom pressure decreases; and (d) the anisotropic fracture network deformation will significantly decrease permeability, and the cumulative gas production is positively correlated with angle between main facture and horizontal well. The study will can play a significant role in the simulation of shale gas production.

Reconstruction of digital rock considering micro-fracture based on multi-point statistics

The macroscopic transport properties of shale are determined by microscopic pore structure, which displays typical multi- scale characteristic with pore size ranging from nanometers to microns and well development of natural micro cracks. The physical experimental method is limited by the contradiction between the selected resolution and imaging sample size. Therefore it is significant to obtain the representative elementary volume to simultaneously incorporate nano-micro pore information and micro-fracture characteristics. To deal with this, numerical reconstruction algorithms are commonly applied to reconstruct pore structure based on easily obtained 2D images and in recent years are applied to reconstruct multi-scale shale porous media. The reconstruction algorithms mainly include the truncated Gaussian random field, simulated annealing, Markov chain Monte Carlo sequential indicator simulation, multiple-point statistics, phase-recovery algorithm and process-based method. In this study, a pattern based on multipoint statistics (MPS) method is proposed to account for multi-scale pore structure characteristics in shale. MPS comes from a statistical method to reconstruct large-scale patterns using pixel-based representations and can characterize the correlation between multiple points compared with traditional two-point statistics. First, different pore types and fractures are identified based on the gray scale shale image. Second, multi-scale shale images are constructed by containing formation of cracks with different properties as well as randomly pore-fracture distribution pattern and then treated as the basic training images. Next, the search tree is used to store and classify occurrences of all pore-fracture distribution patterns that are obtained after the multiple data template scanning the training image. Data template capturing pattern library and conditional probability functions are both stored in the search tree to reflect the long-range connectivity. Accordingly, a random path is defined to visit all unsampled voxels. For every new voxel, the data event is obtained by using the previous template and the conditional probability distribution function (CPDF) of this voxel is established from the search tree. The state value is taken stochastically and put into conditional events for the future voxel simulation. The following voxels are simulated on the random path until a new 2D image is produced. Finally, the type-method interpolation approach is employed to construct the potential simulation space. In order to evaluate the consequence of reconstruction, the constructed images are compared with the training image in terms of autocorrelation function, pore morphology, topology structure and permeability value. Different fracture distribution patterns including orthogonal fractures, dipping fractures and fractal rough fractures are generated. The structure and transport properties of generated pore-fracture models are compared with those of the training images to test the robustness of the proposed reconstruction algorithm. The results show that the constructed images display similar characteristics as training images and their property values are identical with each other under the conditions of adding different types of cracks, which verifies the rationality of proposed method.

Effects of coarse aggregates on chloride diffusion coefficients of concrete and interfacial transition zone under experimental drying-wetting cycles

Chloride ions diffusion into concrete is one of the most significant factors for reinforced concrete (RC) structures exposed to marine environment, and this can deteriorate reinforcing steel in concrete and cause steel corrosion, ultimately, shorten the durability and serviceability of RC structures. In this paper, the in-door physical experiment method was adopted to explore the effects of natural coarse aggregate on chloride concentration profiles and diffusion behaviors for concrete specimens under man-made exposure condition of drying-wetting cycles. All investigations were based on 10 concrete mixture designs containing variable volume fractions and maximum sizes of natural coarse aggregate for maximum exposure period of 170 days. The chloride profiles versus exposure time, coarse aggregate volume fraction and maximum size were discussed in this paper. The time-dependent model of surface chloride concentration, and the multifactor model of chloride diffusion coefficient of concrete specimens included exposure time, volume fraction, and maximum size of coarse aggregate were developed based on the experimental measurements. In addition, an empirical prediction model for estimating the chloride diffusion coefficient of interfacial transition zone (ITZ) by the consideration of coarse aggregate was determined. Finally, the accuracy and reasonability of the two models of chloride diffusion coefficients for concrete and ITZ considering the effects of coarse aggregate were validated in terms of the meso-scopic finite element numerical simulation method for chloride diffusion into concrete.