Physical Modeling Method Research Articles

Physical Modelling in Development of the Regulatory Framework for Transport Construction

Application of the physical modelling method to justify regulatory requirements for design of structures for engineering protection of transport facilities from wave action is considered using the example of three completed research and development works. The described experimental studies of interaction of waves with structures were carried out in wave basins and tanks.The objective of the research is to scientifically substantiate the requirements of regulatory documents for design of shore protection to ensure safe operation of the roadbed of railways and roads, bridge supports, and other transport structures operated under conditions of wave action on the shores of seas and lakes. In this case, the normalised parameters, depending on the hydrological (wind-wave and sea-level regimes of the water area and current), geological-morphological and lithodynamic (coastal zone dynamics) conditions are the types of protective structures used, planned and design solutions for protective hydraulic structures (location, elevations, dimensions), as well as the materials and products used for construction (including quality requirements).The experimental design part of the described studies was carried out by the method of physical (hydraulic) modelling in wave basins and tanks. Physical modelling was carried out in accordance with the theory of similarity. At the same time, a «flat problem» is solved in wave tanks, and a «spatial problem» is solved in wave basins.

Optimization mathematical model of a contact air cooler for a mine turbocompressor

Purpose. Establishing the dependencies of rational parameters of turbocompressor contact air coolers on the operating mode and initial conditions. Methodology. The methods of analytical research, mathematical modeling, physical modeling, and mathematical statistics were used in the study. Findings. As a result of the research, an optimization mathematical model of the mine turbocompressor air cooler was developed, which allows establishing its rational parameters depending on the initial conditions and operating modes of the turbocompressor. The adequacy of the theoretical studies was proved on a specially designed experimental setup. The obtained dependences make it possible to minimize the theoretical flow rate at the inlet to the uncooled section of the turbocompressor, which reduces the specific energy consumption for the compressed air production. Originality. For the the first time, a method has been developed for determining the rational parameters of contact air coolers when the initial temperature of water, air, and air pressure changes, which allows developing a methodology for the constructive calculation of the contact cooling system of mine turbocompressors. Practical value. Compressed air is widely used in all industries. It is one of the most common energy carriers in industrial enterprises, and the devices associated with its distribution and processing are an energy-intensive complex industrial energy system; the level of its perfection depends on the performance of technological processes that use compressed air. Compressed air is widely used in the mining industry (ore mining and fuel production). Compressed air is produced by turbocompressors. To increase the efficiency of the compressor, compressed air coolers are used. A significant weakness of the standard compressor cooling system is the rapid contamination of the heat exchange surfaces of air coolers with scale layers, which leads to a decrease in their efficiency and an increase in the specific energy consumption for compressed air production. This disadvantage is not found in the Venturi tube – centered droplet separator contact air coolers. As a result of the study, the dependencies were obtained and used to develop a methodology for the constructive calculation of contact air coolers for a mine turbocompressor.

Study of Grouting in the Hydraulically Activated Subfoundation Soils Using the Comprehensive Approach

Introduction. The large-scale “wet” closure of collieries had led to irreversible changes in the underworked rock mass. First of all, there took place the mine-water level rise and hydraulic activation of buildings’ subfoundation soils, which induced the new geodynamic effects and hazardous deformations of buildings. Therefore, it is necessary to carry out the reconstruction of buildings’ subfoundations on the underworked territories. Under these circumstances, the high-pressure jet grouting with viscoplastic grouts using the hydraulic fracturing is considered a highly-promising trend of soil grouting. The work aims at studying the parameters of grouting and the degree of consolidation of hydraulically activated soils on the underworked territories.Materials and Methods. The research was carried out with the rock full scale specimens, taking into account their physical-mechanical and strain-strength properties. The comprehensive approach to research implied studying the geotechnical conditions and the technological parameters of rock grouting along with the quality of stabilisation and waterproofing of hydraulically activated soils.Results. In accordance with the comprehensive research methodology, at the first stage, the geotechnical and miningengineering analysis of the underworked territories were carried out and the geostructural typification of the ShakhtinskNesvetaevsky district territories was substantiated depending on the thickness of the covering deposits. At the second stage, the grout pad formation parameters at contact with the parent rocks were analytically determined. Moreover, for dispersive decompacted rocks the consistent patterns and the degree of filtration consolidation were established in the empirically-analytical way by viscoplastic grout injection. Using the computer and physical modeling method, the consistent patterns of subfoundation soils deformation before and after grouting were obtained for three geostructural types. At the third stage, the field studies of the grouting parameters and quality were carried out during the subfoundations reconstruction of two buildings in the city of Shakhty. It was proved that grouting in the hydraulically activated soils increases their strength up to 0.4 MPa and reduces subfoundations deformation by 2–2.5 times.Discussion and Conclusions. Application of the comprehensive methodology to the study of grouting in the hydraulically activated soils of the underworked territories made it possible to substantiate the process flow schemes and parameters of consolidation and waterproofing of dispersive and fractured hard rocks. Based on the analytical, computer, laboratory and field study results, the consistent patterns and the degree of variation in the deformation-strength properties of the hydraulically activated subfoundation soils after viscoplastic grouting were established.

Physical modeling of complex lithofacies volcanic edifices and seismic characteristics

Abstract The Songnan fault basin contains a significant distribution of basaltic volcanic rock structures, and serves as one of the primary types of reservoir in the area. Volcanic formations exhibit notable distinctions when compared to conventional oil and gas reservoirs, and the precise seismic response mechanism of these formations remains uncertain. Hence, it is imperative to investigate the seismic response mechanism of volcanic formations to enhance the geophysical characterization capability of oil and gas reservoirs composed of igneous rock. The seismic physical simulation model method is used to obtain dependable data for investigating the seismic response mechanisms of volcanic structures. This is achieved by constructing intricate physical models of rocks and volcanic structures. Our team focused on the development of materials and processes for accurately modeling various rock and volcanic structures, and we successfully designed and produced a three-dimensional physical model representing volcanic structures in the Chaganhua area. Furthermore, we conducted thorough data acquisition and analysis to examine the seismic response characteristics and sensitive properties of different geological bodies. We improved the accuracy of identifying different lithofacies of volcanic rocks by extracting different seismic attributes. This study presents a reliable approach for elucidating the seismic response mechanism of intricate rock and volcanic formations. It can also serve as a valuable resource for processing and interpreting seismic data in the specific study region. The conclusion that weak seismic reflection signals in volcanic rocks are effective signals rather than noise could be more conducive to accurate analysis and description of volcanic structures.

A Pulsed Current Application to the Deformation Processing of Materials.

A review of studies on the electroplastic effect on the deformation process in various conductive materials and alloys for the last decade has been carried out. Aspects, such as the mode and regimes of electric current, the practical methods of its introduction into materials with different deformation schemes, features of deformation behavior accompanied by a pulsed current of different materials, structural changes caused by the combined action of deformation and current, the influence of structural features on the electroplastic effect, changes in the physical, mechanical, and technological properties of materials subjected to plastic deformation under current, possible mechanisms and methods of physical and computer modeling of the electroplastic effect, and potential and practical applications of the electroplastic effect are considered. The growing research interest in the manifestation of the electroplastic effect in such new modern materials as shape-memory alloys and ultrafine-grained and nanostructured alloys is shown. Various methods of modeling the mechanisms of electroplasticity, especially at the microlevel, are becoming the most realistic approach for the prediction of the deformation behavior and physical and mechanical properties of various materials. Original examples of the practical application of electropulse methods in the processes of drawing, microstamping, and others are given.

Numerical modeling strategies and parametric analyses of platform-type and balloon-type cross-laminated timber (CLT) shear walls under lateral loads

Despite great contributions having been made on the topic of numerical modeling methods for cross-laminated timber (CLT) shear walls under lateral loads, it is still challenging to simulate the nonlinear wall behavior with both computational efficiency and modeling accuracy. In this paper, a series of novel modeling strategies are developed, aiming to provide a potential solution to this challenge. The modeling strategies involve the revised version of a uniaxial hysteretic model for dowel-type timber joints, physical and phenomenological modeling methods for typical CLT connections (i.e., hold-down and angle bracket connections), and a fiber-section-based modeling method for CLT shear walls. The modeling strategies were validated by existing experimental data, and the modeling results showed that the proposed fiber-section-based model is capable of simulating the lateral performance of both platform-type and balloon-type CLT shear walls with sufficient accuracy while maintaining desirable computational efficiency. The fiber-section-based model was then used to conduct parametric studies, investigating the influence of construction methods, wall aspect ratios, connection stiffness, and vertical load magnitudes on the lateral performance of CLT shear walls. The studies showed that the initial stiffness and ductility ratio of balloon-type CLT shear walls were 39.1–47.1% and 13.7–19.4% larger than the platform-type ones, while the ultimate capacity was less affected by construction methods. Slenderer CLT shear walls had lower ultimate capacities and initial stiffnesses, as well as smaller ductility ratios. Stiffer hold-down connections contributed to larger initial stiffness but resulted in the CLT shear wall failing in a less ductile manner. The vertical load had positive impacts on the ultimate capacity, initial stiffness, and ductility ratio of CLT shear walls, although the effect on the ultimate capacity was quite limited.

Estimation of canopy water content for wheat through combining radiative transfer model and machine learning

Canopy water content (CWC) is an important indicator of crop growth. Currently, the hybrid approach, which combines the physical model and machine learning (ML) method, is commonly used for inversing CWC at the regional scale via optical imagery. Although this approach has good inversion accuracy, it suffers from ill-posed issues from the physical model due to the difference between actual and simulated scenes. Meanwhile, the ability of existing ML methods to resolve this difference remains unclear. To fill the above study gaps, we added different degrees of Gaussian noise into the simulated dataset to reduce the differences in spectral reflectance between that simulated by the PROSAIL-5B model and that measured from optimal imagery. Furthermore, this study also compared the performance of different ML approaches (neural network, NN; Gauss process regression, GPR; and kernel ridge regression, KRR) in the retrieval of wheat (Triticum aestivum L.) CWC based on PROSAIL-simulated datasets. Additionally, we also compared the inversion results for the CWC generated by the SNAP Toolbox with those estimated by the hybrid approach. The results showed that the aforementioned hybrid approaches performed well in the retrieval of wheat CWC when Gaussian noise with a mean of zero and a standard deviation of 0.06 (η: 0, 0.06) was added to the simulated dataset. The hybrid model based on GPR had the highest accuracy of estimation for the CWC (RMSE = 0.0096 g/cm2, RRMSE = 22.2%), when compared with NN or KRR (NN: RMSE = 0.0105 g/cm2, RRMSE = 26.9%; KRR: RMSE = 0.0099 g/cm2, RRMSE = 24.3%). It also outperformed the existing CWC-retrieval algorithms among the SNAP Toolbox (RMSE = 0.027 g/cm2, RRMSE=44.1%). Our results demonstrate that the hybrid approach in combination with GPR and the physical model can accurately retrieve the CWC of crops, thus confirming that the approach is suitable for estimating the CWC.

Physics-Guided Generative Adversarial Networks for Sea Subsurface Temperature Prediction.

Sea subsurface temperature, an essential component of aquatic wildlife, underwater dynamics, and heat transfer with the sea surface, is affected by global warming in climate change. Existing research is commonly based on either physics-based numerical models or data-based models. Physical modeling and machine learning are traditionally considered as two unrelated fields for the sea subsurface temperature prediction task, with very different scientific paradigms (physics-driven and data-driven). However, we believe that both methods are complementary to each other. Physical modeling methods can offer the potential for extrapolation beyond observational conditions, while data-driven methods are flexible in adapting to data and are capable of detecting unexpected patterns. The combination of both approaches is very attractive and offers potential performance improvement. In this article, we propose a novel framework based on a generative adversarial network (GAN) combined with a numerical model to predict sea subsurface temperature. First, a GAN-based model is used to learn the simplified physics between the surface temperature and the target subsurface temperature in the numerical model. Then, observation data are used to calibrate the GAN-based model parameters to obtain a better prediction. We evaluate the proposed framework by predicting daily sea subsurface temperature in the South China Sea. Extensive experiments demonstrate the effectiveness of the proposed framework compared to existing state-of-the-art methods.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ СКОРОСТИ И СПОСОБА РАЗЛИВКИ РАСПЛАВА НА РАЗВИТИЕ ОСЕВОЙ ЗОНЫ В МОДЕЛЬНЫХ СЛИТКАХ

The paper presents the results of laboratory studies of the effect of the method and speed of casting the melt on the solidification process and the features of the formation of the axial zone of a large ingot. The research was carried out by the method of physical (cold) modeling on a model of an ingot weighing 19.6 tons. Sodium sulfuric acid (crystalline hyposulfite) was used as a modeling solution. The casting of the melt into the mold-mold was carried out from above. It is shown that the change in the melt casting rate has a significant effect on the length of the axial zone. It is established that a decrease in the melt casting rate leads to an increase in the direction of crystallization and an improvement in the structure of the axial zone of the ingot. It has been found that model ingots that were cast with refilling of the profitable part by melt after a certain time interval after pouring the ingot body, solidify 1.4 times faster than the ingot cast according to classical technology.

Momentum and thermal transport analysis in MHD nanofluid through the thermally heated square conduit: Finite element method

ObjectiveThe purpose of this investigation is to report the thermal performance of water-based nanofluids with two different types of hybrid nanofluids for the cooling process of the radiator inside the thermally heated square cavity under the addition of thermal radiation and magnetic field by using the finite element method. Research gapThe heat transfer analysis of MHD nanofluid with the suspension of titanium alloy Ti6A14V and aluminum alloy AA7075 in cavity flow problems under the effects of thermal radiation and thermal boundary conditions by using the Galerkin finite element method is not reported before. NoveltyIn this numerical investigation, the novel mathematical model of two types of titanium alloy Ti6A14V (class of titanium) and aluminum alloy AA7075 is proposed first time in the cavity flows under the influence of a uniform magnetic field and non-uniform thermally heated bottom wall. The momentum and energy equations are updated with terms of magnetic field and thermal radiation, respectively. The cavity is filled with AA7075- Ti6A14V/water nanofluids. Two parallel vertical walls of the cavity are set at constant temperatures (Tc) and the top one is adiabatic while the temperature at the lower wall is taken as the variable. Method of solutionThe physical model is composed in terms of nonlinear differential equations and transformed into a dimensionless form by using suitable non-dimensional quantities. The Galerkin finite element method along with iterative Newton’s Raphson method is selected to simulate the problem and obtain the numerical solution with a high degree of accuracy. The results are illustrated for fixed Prandtl number Pr=10.0 throughout the calculation, Rayleigh number 1000≤Ra≤100000, nanoparticle volume friction 0.0≤ϕ≤0.05 Hartman number 0≤Ha≤10 and thermal radiation parameter 1.0≤Ra≤10.0. Both grid independence tests and comparison tests are directed to get the accuracy of the established model. Important findingsThe computational results revealed that the aluminum alloy (AA7075) alloys nanoparticles are more productive as compared to titanium (Ti6Al4V) alloy nanoparticles in terms of enhancing the thermal features of water-based nanofluid. The aluminum alloy nanofluid and titanium alloy nanofluid provide 3.9 % & 5.7 % and 2.9 % & 4.2 % more heat transfer at the bottom and side walls as compared to regular fluid. ApplicationsThe current nanofluid models are more efficient than the conventional model to control the heat transfer rate and flow phenomena. The computational results revealed that if the radiator is assembled by using the modern concept of hybrid nanofluid then that will increase the heat transfer of the engine and enhance the lifespan of the machinery.

Data-driven nonlinear MIMO modeling for turbofan aeroengine control system of autonomous aircraft

The mathematical modeling problem of a general turbofan aeroengine control system used in autonomous aircraft is investigated in this paper. Unlike the thermodynamics or physical mechanism-based modeling methods in the existing literature, a pure data-driven modeling approach is presented with high accuracy via online and offline data only. This is achieved by using the nonlinear autoregressive neural network with exogenous inputs (NARX) neural network. In comparison with the existing NARX-based MIMO modeling methods, the series–parallel structure and the parallel structure are integrated for the neural network training. Faster convergence and stability as well as higher modeling accuracy are thus achieved. Another feature of this approach is that it is independent of all the components’ dynamics in the turbofan aeroengine. Simulation results are given to verify the effectiveness of the proposed modeling approach. This is further validated by experimental testing with the method applied to mini turbofan aeroengine testbed.

Investigation of the Processes Occurring During the Operation of the Torque Converter Hub in the Belarusian Autoworks Gearbox during CAE Modeling

The main objective of the study is to identify and eliminate the causes of breakdowns in the torque converter hubs of mining dump trucks Belarusian Autoworks. The relevance of the work carried out: during the operation of dump trucks based on Belarusian Autoworks vehicles, in open pit conditions, according to enterprises operating such equipment, in the period from 2019 to 2021, 75% of the failures and breakdowns of equipment occurred due to the fact that the hub of the torque converter impeller is intensively loaded a part, which during its operation is affected not only by mechanical loads, but also by temperature and others leading to the failure of the specified unit in 85% of cases. For example, hydrodynamic forces that arise during the period of immersion of gear teeth in an oil bath, and so on. Therefore, it is proposed to conduct a comprehensive study of the processes occurring with the wheel hub and identify the main loaded places. Taking into account the analysis carried out, it is possible to produce a batch of wheel hubs with updated parameters and conduct their full-scale tests. The novelty of the work carried out lies in the analysis of the operating conditions of the hub, which revealed a high boundary pressure that occurs at the point of transition from the air to the oil bath. The object of research is the study of the processes that occur during the operation of the torque converter hub, which affect the structure and occur in the hub itself. Research objectives: - learn the ways and methods of conducting CAE analysis; - analyze the design parameters of the installation that occur in the torque converter bushing. Research methods: When performing the dissertation work, methods of physical and mathematical modeling and system analysis of information, laboratory, bench and operational tests using computer and high-precision measuring equipment were used

Fourier Ptychographic Reconstruction Method of Self-Training Physical Model

Fourier ptychographic microscopy is a new microscopic computational imaging technology. A series of low-resolution intensity images are collected by a Fourier ptychographic microscopy system, and high-resolution intensity and phase images are reconstructed from the collected low-resolution images by a reconstruction algorithm. It is a kind of microscopy that can achieve both a large field of view and high resolution. Here in this article, a Fourier ptychographic reconstruction method applied to a self-training physical model is proposed. The SwinIR network in the field of super-resolution is introduced into the reconstruction method for the first time. The input of the SwinIR physical model is modified to a two-channel input, and a data set is established to train the network. Finally, the results of high-quality Fourier stack microscopic reconstruction are realized. The SwinIR network is used as the physical model, and the network hyperparameters and processes such as the loss function and optimizer of the custom network are reconstructed. The experimental results show that by using multiple different types of data sets, the two evaluation index values of the proposed method perform best, and the image reconstruction quality is the best after model training. Two different evaluation indexes are used to quantitatively analyze the reconstruction results through numerical results. The reconstruction results of the fine-tuning data set with some real captured images are qualitatively analyzed from the visual effect. The results show that the proposed method is effective, the network model is stable and feasible, the image reconstruction is realized in a short time, and the reconstruction effect is good.

Analysis of the retrofitting of a universal vacuum cryogenic spectrophotometer

The paper considers the modernization of the methodology for studying astrophysical ice and cold interstellar dust. An experimental method of physical modeling using a vacuum cryogenic installation is presented. The nodes of the universal vacuum cryogenic spectrophotometer where it is necessary to modernize, retrofit for the subsequent improvement of measuring capabilities in scientific research are considered in detail. The IR spectra of polystyrene were obtained on the IRS-29 and FSM 2203 spectrometers, the results of the obtained characteristic absorption bands were compared with the values of the reference spectrum of polystyrene, and the expanded uncertainty was calculated. To assess the accuracy of the measurement results, we calculated the expanded uncertainty according to the IR spectrometer calibration procedure. The wavenumber scale calibration uncertainty was determined by direct measurements as the difference between the wavenumber value corresponding to the maximum ordinate of the absorption line of a standard polystyrene film sample. In this work, an analysis of the completed retrofitting of a universal vacuum cryogenic spectrophotometer was carried out. N2O spectra were taken, obtained at a temperature of 16 K in the wave number range of IR spectrometers from 370 to 4200 1/cm with the designation of the corresponding absorption bands. The studies carried out in this work are aimed at improving the accuracy of measurements, which guarantees and improves the quality of scientific research.

Research on infrared nondestructive testing and thermal effect analysis of small wind turbine blades under natural excitation

In recent years, with the increase of wind power generation and the rapid growth of the number of wind turbines installed, the safety monitoring of wind turbine blades has also attracted wide attention. To further study the thermal effect of wind turbine damaged blades under natural excitation in summer in northern China, based on the outdoor infrared non-destructive testing of wind turbine blades, a numerical simulation of wind turbine blades with wear damage is carried out by using the fluid solid heat transfer theory in COMSOL multi-physical field coupling software. The best detection light condition is obtained, in which the detection effect of wear damage is the best when the light intensity reaches 1000 W.m−2 or above at noon. The simulation results are basically in agreement with the experimental results. And compared with the previous physical modeling method using natural convection heat transfer coefficient to replace wind speed, the physical modeling method considering wind speed and air humidity is more consistent with the experimental results, the maximum error value was decreased by 7.46 %, which verifies the rationality of the model and the feasibility of the method. In addition, the blade works in the natural environment for a long time, the thermal stress will have a significant impact on its fatigue strength, so on the basis of this model, the coupling analysis, and then analyze the change of thermal stress in different wind speed. With the increase of wind speed, the temperature on the blade surface gradually decreases and the wind pressure gradually increases. Because the influence of temperature on the stress is greater than that of wind pressure, the stress also shows a gradual downward trend.

Development of technology for production of new materials on traditional wide-strip hot rolling mills using modern methods of numerical and physical modeling. Part 2

The first part of the article presents a modern approach to the technology development for the manufacture of hot-rolled steel with characteristics that exceed the passport values of the equipment of traditional hot strip mills using based on the widespread use of mathematical and simulation methods. The stages of the laboratory experiment and the carried-out investigations are described. In the second part, the results of industrial implementation and their comparison with the results of a laboratory experiment are considered. According to the developed modes of hot rolling on the hot strip mill 2000, industrial batches of rolled products were produced using the technology of direct quenching from rolling heating. The resulting microstructure is a matrix of lower bainite with a share of upper bainite, retained austenite, and Fe3Mo3C carbide phase in total no more than 10 %. The formed structure provides in rolled products a strength of 1075 MPa and a relative elongation of at least 10 %. Due to the formation of a dispersed bainitic microstructure, the tension diagram is characterized by a degenerate yield plateau. The developed deformation rolling mode in the roughing and finishing groups of stands makes it possible to form elongated “fritter-like” grains with a grain length to thickness ratio of 2.5–3.0 before accelerated cooling, due to which the KCV–40 impact strength values significantly exceed the consumer requirements (170>27 J/cm2). Using modern numerical simulation methods, the parameters of accelerated cooling on the run out table and the downcoiler settings of the hot strip mill were determined, which made it possible to achieve the desired temperature state of the strip and defect-free coiling from the first piece. The convergence of the results of laboratory and industrial experiments is shown.The research was carried out within the framework of the program of strategic academic leadership of the Russian Federation "Priority-2030", aimed at supporting the development programs of educational institutions of higher education, the scientific project PRIOR/SN/NU/22/SP5/26 "Creation of innovative digital tools for the use of applied artificial intelligence and advanced statistical analysis of big data in technological processes for the production of metallurgical products.

Active Polarization Imaging for Cross-Linear Image Histogram Equalization and Noise Suppression in Highly Turbid Water

The absorption and scattering of impurity particles in turbid water cause the target signal light to be attenuated and to produce backscattered light, resulting in the reduced quality of underwater polarimetric imaging. As water turbidity increases, the effect of backscattered light becomes greater, making polarization imaging in highly turbid water a challenge. Theory and experiment show that the increase in the intensity of backscattered light leads to high noise gain in the underwater active polarization imaging model. In order to enhance image contrast and suppress noise gain in highly turbid water, we propose an underwater imaging enhancement method that appropriately combines the non-physical and physical models. The method uses contrast limited adaptive histogram equalization (CLAHE) for a certain number of cross-linear images (Imin) before calculating their polarization enhancement images, and it constructs joint filtering (multi-frame averaging and bilateral filtering) to suppress the high noise gain introduced by the imaging model and CLAHE. The experimental results in highly turbid water validate the rationality and feasibility of the proposed method, and the comparative processing results (52.7~98.6 NTU) outperform those of the conventional non-physical and physical model methods. The method maintains the complexity of the system and facilitates the application of conventional polarimetric imaging in harsher underwater environments.

Simulation of substrate coupling for mobile communications SoC – A 20 GHz VCO case study

An innovative substrate coupling simulation methodology with on-the-fly extraction and validation of CMOS substrate parasitic elements, combining boundary element method (BEM) with a computational python based physical layout extraction and RC modeling method, is presented in this work. The proposed methodology is seamlessly integrated into the standard virtuoso based custom circuit design flow and allows the designer to extract fast and accurate a substrate RC mesh, valid from DC to GHz, enabling crosstalk impact estimation and gaining insight on substrate coupling effects from the early stage of the design process until the prototype phase. The proposed substrate crosstalk modeling flow is validated using a 20 GHz VCO circuit as a crosstalk victim. The VCO vehicle is designed using a 65 nm RFCMOS process and the respective RF devices of the specific PDK are used. The PCB transmission line and the package parasitics must be considered as to achieve more accurate and realistic simulation results. The simulation scheme is set using a layout footprint test case and two separate signal injection tap points, each at a certain distance from the VCO victim. This simulation scheme can provide various substrate signal crosstalk scenarios by injecting signals that consist of multiple frequencies into the substrate. Three simulation analysis types, Transient, QPSS and ENVLP, are performed as to be able to designate which analysis is the most suitable for crosstalk simulation in terms of simulation time, accuracy and compatibility. Finally, as a sanity check and methodology validation, crosstalk isolation trends with respect to the aggressor distance and the substrate signal frequency are extracted and compared with the State-of-the-Art results available in literature.

Research on Laboratory Test Method of Wave Energy Converter Wave-Wire Conversion Ratio in Irregular Waves

The laboratory test of the wave energy converter model is an important means to evaluate the performance of the device. At present, there are few performance tests for complete specifications under the irregular wave. Referring to the test methods and standards at home and abroad, combined with the actual test work experience in the laboratory, using the irregular wave power calculation formula with the effective wave height and the spectral peak period as parameters, then the wave-wire conversion ratio test method of the wave energy converter physical model under irregular waves in the laboratory is proposed. The method is applied to the basin test experiment of the physical model of the horn-shaped backward bent duct buoy (BBDB) wave energy converter. The research results show that the established test method and process of wave-wire conversion performance have achieved good application results in the irregular waves laboratory test, and can better reflect the device operating characteristics in real sea conditions. The test results provide data support for the model design of the wave energy converter in the next test stage, the demonstration test of the prototype, and the prediction of power generation in real sea conditions.

Automatic water level regulator with flexible working bodies in form of partition structure for trapezoidal channels

To improve the designs of hydraulic automatic water level regulators with flexible working bodies for channels, the object of research was developing and studying an innovative design of an autoregulator of the water level with flexible working bodies in the form of a partition structure for trapezoidal channels. The study℉s main purpose was to create a design for trapezoidal channels that do not allow channel narrowing and provides automatic level control, draining excess water, washing deposits in front of the partition, and determining its throughput. The developed design consists of a gate with flexible working bodies and a water level regulator combined with it. The article presents a theoretical formula for determining the flow rate of lateral water flows through the gate of the water level autoregulator. Experimental studies were carried out on an experimental installation by the method of physical modeling using the criterion of geometric similarity of the model and nature. As a result of these studies, simpler formulas were obtained for determining the flow rate of lateral water flows through the gate and a formula for determining the total flow rate of water passing through the gate of the water level autoregulator with flexible working bodies for trapezoidal channels for use during operation.