Computational Experimental Methods Research Articles

Morphology of discontinuous metal films with pronounced secondary nucleation

Computer experimental methods are used to study the initial stages of growth of metallic layers on a dielectric substrate. The main focus of attention is the growth phases of the metallic layers in which secondary nucleation phenomena are more pronounced. Standard morphological methods are tested and new ones are proposed to describe these kinds of strongly inhomogeneous structures. The simulated metallic films were generated using an atomistic model that combines both molecular dynamics and Monte Carlo approaches. It is shown that classical morphological methods such as the quadrat counts method do not provide satisfactory results for the image analysis of such structures, and consequently, new morphological approaches are proposed that will allow the analysis of such structures.

Simulating Environmental Innovation Behavior of Private Enterprise with Innovation Subsidies

By reducing innovation costs, innovation subsidies can help private enterprises convert their production modes to green production. Based on method of computational experiment in social science, we construct a dynamic model for environmental innovation behaviors of private enterprises to simulate their evolution process in different market mechanisms, product competitions, and innovation subsidies and explore the impact of different subsidy modes on environmental technological innovation behaviors. The experimental results show that, under actions of multiagents, the combination of market subsidy and technology transformation subsidy can achieve the highest utilization efficiency of subsidy funds. However, when level of innovation technology is low, the innovation process should be subsidized at the same time to improve the competitiveness of innovative products. Besides, according to the level of innovation technology, flexible innovation subsidy combinations can be adopted to optimize subsidy in the different stages. The experimental results are of great significance for increasing efficiency of innovation subsidy funds and promoting green sustainable development of private enterprises.

Расчетно-экспериментальный метод анализа волн в нерегулярных связанных полосковых линиях с сосредоточенными неоднородностями

Расчетно-экспериментальный метод анализа волн в нерегулярных связанных полосковых линиях с сосредоточенными неоднородностями

Parameters for simulation of the thermal state and fire-resistant quality of hollow-core floors used in the mining industry

The statistical data of the fire and technogenic safety in Ukrainian mines have been studied. A literary analysis has been made of advanced expertise in determining the fire resistance of building structures. It has been studied the thermal state and fire resistance of hollow-core floors using the fire tests and the calculated determination of the fire resistance degree of a structure based on a two-dimensional model of thermal conductivity and convective heat transfer implemented in the ANSYS R17.1 software complex. The fire test of hollow-core floor has been analysed and the use of a computational-experimental method is proposed to determine the parameters when simulating the thermal state and the fire resistance of both protected and unprotected hollow-core floors. A technique has been developed for simulating the thermal state and the fire resistance of hollow-core floors, which can be used in assessment of the fire resistance degree of reinforced concrete building structures both in industrial construction and in the mining industry.

Radially-Symmetric Thermal Wave as a Source of Information on the State of Inhomogeneities in Plates and Sheaths

An experimental-computational method of non-stationary thermal diagnostics and non-destructive testing of metallic and non-metallic sheaths and plates, including their inner surfaces inaccessible for direct inspection, by analyzing a non-stationary temperature field generated by the point dynamic heating of the outer surface of the sheath and registered by a thermal imaging device is described.

Determination of the Fault Zone by the Level of Short-Circuit Currents

The methods of determination the fault zone according to the parameters of the emergency mode, which can be used to improve the performance of technical perfection of current protection lines of distributive 6–10 kV one-way power networks, are considered. The advantage of the algorithm of determination the zones of short circuit (SC) according to the level of emergency currents as compared to the remote unilateral method addressing the parameters of the damaged loop corrupted loops (loops) is noted. Calculation of the estimated distance to the point of SC on the basis of difference of damaged phase currents has been proposed, that enables the independence of the obtained result on the type of the fault. A technique for increasing the reliability of the method for determination the short-circuit zone by the level of emergency currents based on information about the type of damage has also been proposed. The effect of load currents and contact resistances of different levels on the magnitude and nature of the changes in the errors of the calculated distance to the short circuit was investigated by the method of computational experiment. The levels of contact resistances relative to the total resistance of the line depending on the place of SC occurrence are determined that provides reliable determination of the fault zone; it is demonstrated that the nature of their alteration is approximately the same for lines of medium and long length. The expediency of correction of the calculated distance to the fault location in many cases of short circuits through the contact resistance so to improve the protection capacity of the high-speed current protection stage is demonstrated. Based on the results of the computational experiment, correction factors for the correction of the value of the emergency current have been obtained; on the basis of the latter the fault zone is determined. The estimation of efficiency of the proposed method of correction has been carried out; it is shown that its application makes it possible to improve the accuracy of determination the fault zone and to expand the zone of instantaneous shutdown of short circuit. The dynamic properties of the proposed algorithm for different modes of the line operation have been investigated; it is ascertained that, in the worst case, the determination of the short circuit zone for a time not exceeding 27 ms is provided.

The neurocomputing using of the development metamodels stage in the optimal surrogate antennas synthesis process

Introduction. A computational developing metamodels technology for optimal antenna synthesis problems is proposed. This computational technology is created using methods of data mining, artificial intelligence and modern computer methods of experiment planning. To develop an approximation model, the mathematical apparatus of artificial neural networks, namely the RBF-network, is applied. Analysis of metamodels developing research. The computer experiment plan is performed with the help of Sobol’s $LP_\tau$-sequences $(\xi_1, \xi_2)$, which in the general case uniformly fill the points with the search space in the unit hypercube. Verification of the proposed technology is performed on test functions of the two variables goal. The obtained metamodels have rather high accuracy of approximation and improved computational efficiency. The created computing metamodels developing technology of provides high modeling speed which makes a possible realization of optimum antennas synthesis procedure. This technology is effective and correct for more complex problems of approximating multidimensional hypersurfaces. Metamodels developing. To develop the RBF-metamodel, an automatic and user-defined strategy with random sampling is used in the ratio: 70% - training, 15% - control, 15% - test. Training and control samples were used in the metamodel developing, and the test - for cross-verification. At the stage of training best neural networks selection was carried out by indicators: determination coefficient $R^2$; standard forecast error deviations ratio and learning data $S.D.ratio$; average relative model error magnitude MAPE,%; residual average squared error $MS_R$; residues histogram; scattering diagrams. Results of numerical experiments. Obtained metamodels for test functions $f_1(x,y)$ - RBF-2-130-1 (44); $f_2(x,y)$ - RBF-2-150-1 (6); $f_3(x,y)$ - RBF-2-185-1 (10) have a high enough approximation accuracy and improved computational efficiency. For these metamodels, we checked the adequacy and informativeness of Fisher's criterion. The results of metamodels checking adequacy calculations at the stage of response surface recovery are presented. The created computing metamodels developing technology provides a high simulation speed, which makes possible the implementation of the procedure for optimal antennas synthesis. This technology is effective and correct for more complex problems of multidimensional hypersurfaces approximation. Conclusions. The numerical experiments results analysis is evidence of the high efficiency of the proposed computing developing metamodels technology, which is created using methods of intellectual data analysis, artificial intelligence and modern computer experiment planning methods. The metamodels developing with its use are characterized by fairly high accuracy of approximation and improved computational efficiency. It is these advantages that allow their using with the optimal surrogate antennas synthesis.

Managing Traditional Solar Greenhouse With CPSS: A Just-for-Fit Philosophy.

The profit of greenhouse production is influenced by management activities (e.g., environmental control and plantation scheduling) as well as social conditions (e.g., price fluctuation). In China, the prevailing horticultural facility is the traditional solar greenhouse. The key existing problem is the lack of knowledge of growers, which in turn leads to inefficient management, low production, or unsalable products. To secure effective greenhouse management, the production planning system must account for the crop growing environment, grower's activities, and the market. This paper presents an agricultural cyber-physical-social system (CPSS) serving agricultural production management, with a case study on the solar greenhouse. The system inputs are derived from social and physical sensors, with the former collecting the price of agricultural products in a wholesale market, and the latter collecting the necessary environmental data in the solar greenhouse. Decision support for the cropping plan is provided by the artificial system, computational experiment, and parallel execution-based method, with description intelligence for estimating the crop development and harvest time, prediction intelligence for optimizing the planting time and area according to the expected targets (stable production or maximum gross profit), and prescription intelligence for online system training. The presented system fits the current technical and economic situation of horticulture in China. The application of agricultural CPSS could decrease waste in labor or fertilizer and support sustainable agricultural production.

The research of possibilities for fast calculation of median consensus rankings

We investigated the possibility of fast computation of collective expert estimates of the median type. Despite the widespread use of the Kemeny-Snell and Cook-Seiford medians for calculating the collective expert estimates, the possibilities to reduce the time required to calculate median consensus ranking through the application of the assignment problem and known algorithms for solving it, have been insufficiently investigated. In contrast to the most known methods, the method proposed in this paper is not approximated and retains the original median axiomatics of Kemeny. We investigated a possibility for calculating the Kemeny-Snell and Cook-Seiford medians using the assignment problem applying methods of computer experiment. We estimated the time required to calculate median rankings by four different algorithms for solving the assignment problem. It was established that the proposed method, at a moderate number of alternatives (n<50), computes median rankings over the time close to a real time mode. It is also shown that, in contrast to other methods, the calculation of median rankings using the assignment problem does not depend on coherence degree of individual expert rankings. The results obtained are useful for the practical application of the examined procedure in network expert systems. In such systems, the computation time of a consensus ranking should be close to real time. In addition, in the network expertise systems, due to the random gathering of a team of experts, there is a possibility of the low level of coherence in individual rankings. For the examined procedure, that does not affect the duration of computation. This allows us to recommend the developed computational procedure for a fast search for median consensus rankings by Kemeny-Snell and Cook-Seiford for practical application in the systems of network collective expertise.

A simplified analytical method for the pressure of tilt hydrostatic journal bearing

PurposeThis paper aims to present a simplified method to predict the pressure of the recess, no matter whether the tilt center coincides with the geometric center of the hydrostatic journal bearings.Design/methodology/approachTo validate the effectiveness of the presented model, computational fluid dynamics (CFD) method and experimental method are performed in this study.FindingsBy comparing the CFD results and the experimental results, the pressure of the recess is related to the tilt direction, the tilt center, the width of the land and the circumferential angle of the land.Originality/valueThe mathematic model requires equivalent resistance of land edge – tilt position, tilt direction, tilt angle and the thickness of oil film instead of any digital iteration. Furthermore, a novel experimental apparatus including a circular hydrostatic bearing called ball bearing is designed to study the tilt effect produced by manufacturing error and offset load force on the pressure of the recess.

Development and Investigation of a Two-Layer Metal—Ceramic Material for Protective Barriers in Conditions of High-Speed Impact

The possibility of improving the physico-mechanical characteristics of composite materials used in protective structures against a high-speed impact is considered. By means of self-propagating high-temperature synthesis, a two-layer cermet is obtained: the front layer is a cermet based on titanium diboride with a titanium nickelide bond, and the back layer is a titanium alloy. The study by the computational-experimental method of the impact resistance of this composite in comparison with a homogeneous titanium plate showed a qualitative advantage expressed in the absence of a shock crater in a cermet plate after a collision with a steel spherical impactor and stronger deformation and prefracture of the impactor. The two-layer cermet has a high resistance to the penetration of the steel impactor.

Accounting the Influence of Cold Creep on Deformation of Structures

A computational-experimental method is proposed, which makes it possible to predict the creep process on a significant time basis (on the order of thousands of hours) on the basis of experimental data obtained on a significantly smaller time base. The study was conducted on titanium alloy at room temperature. It is shown that the obtained results expand the possibilities of using the existing methods for the calculation of structures with regard to creep.

DETECTION OF CURRENT CIRCUITS FAULT FOR DIFFERENTIAL CURRENT PROTECTION

False operation of the differential current protection leads to tripping of the most important electrical power objects. Fault of current transformer’s secondary circuits is one of the most often cause of false operation of the differential current protection. Early determination of this malfunction increases the reliability of the differential current protection and reduces the number of false trips. In the present article the methods of secondary open circuit determining for the differential protection are described. Some of the methods react instantly to the malfunction of secondary current circuits, and the other part identifies fault after a certain time delay. Each of considered methods has its advantages and disadvantages. A new method for determination secondary open current circuits based on the analysis of increments of the RMS values of differential and braking currents has been proposed. In this case, increments are calculated for half the period of the industrial frequency, which provides quick fault determining. The use of the sum and the difference between the increments of the brake and differential currents makes it possible to determine the open circuits in the most sensitive way. The method can be adapted to work with any type of differential protection, including transformer protection. The evaluation of the increment of the RMS current value is performed taking into account the transient process in the Fourier filter. With the aid of a computational experiment, the error limit of such an estimate is determined. The block diagram of algorithm of determination of open circuits on the basis of the analysis of increments of the acting values of brake and differential currents is presented; the principle of its functioning is described. The parameters of operation are determined. The limits of sensitivity of the method are determined, too. The time characteristics of the algorithm have been determined by the method of computational experiment with the of the MatLab Simulink simulation environment.

THE RELIABILITY OF DETERMINING THE SHORT CIRCUIT ZONE OF THE LINES OF 6–35 kV

A method of increasing the reliability of determining the zone of short-circuit at the current step protection of the lines of 6–35 kV with unilateral power, aimed at improvement of their technical perfection, is presented in the paper. Having taken the relative simpleness of the current protection into account the authors consider the unilateral remote method of accounting the parameters of the emergency mode and the type of fault to be the most suitable for the implementation of the algorithm of its functioning as compared with the existing methods of fault location. The major factors affecting the accuracy of determining the short circuit zone based on the remote method are noted. With the use of the method of computational experiment the influence of the load currents and contact resistances of various levels on the magnitude and character of changes of errors of determination of the calculated distance of the point of fault from the protection installation location taking into account the errors of measuring transformers. It is demonstrated that in many cases of arc short circuit in a loaded line in order to define the zone of short-circuit with fair accuracy correction of the estimated distance to the fault as calculated by the parameters of the damaged loop (loops) is required. According to the results of numerical experiments corrective expressions on the basis of two relative asymmetry currents determined by the current values of the differences of the phase currents of the line for detecting a type of a short circuit have been obtained. The assessment of the efficiency of the proposed method has been performed. It is shown that the application of the proposed correction method makes it possible to increase the accuracy of fault zone detection. The dynamic properties of the proposed method applied to different modes of the line functioning have been studied. It is determined that in the worst case the definition of the fault zone for a maximum duration of 26 μsec is provided.

Studies of the binding properties of the food preservative thiabendazole to DNA by computer simulations and NMR relaxation.

Thiabendazole (TBZ) is a commonly used food preservative and has a wide range of anthelmintic properties. In this study, computer simulations and experiments were conducted to investigate the interaction mechanism of TBZ and herring sperm DNA (hsDNA) at the molecular level. Molecular docking showed that TBZ interacted with DNA in groove mode and bound in A-T and C-G base pair regions. Molecular dynamics (MD) was used to evaluate the stability of the TBZ–DNA complex and found that the three phases in MD and the hydrogen bonds helped maintain the combination. NMR relaxation indicated that TBZ had a certain affinity to hsDNA with a binding constant of 462.43 L mol−1, and the thiazole ring was the main group bound with DNA. Results obtained from fluorescence experiments showed that the binding of TBZ and hsDNA was predominantly driven by enthalpy through a static quenching mechanism. Circular dichroism and viscosity measurements proved the groove binding mode. The FTIR results clarified the conformational changes of DNA, that the DNA helix became shorter and compact, and the DNA structure transformed from B-form to A-form.

Computational and experimental study on dynamics behavior of a bionic underwater robot with multi-flexible caudal fins

PurposeThis paper aims to develop a novel type of bionic underwater robot (BUR) with multi-flexible caudal fins. With the coordinate movement of multi-caudal fins, BUR will combine the undulation propulsion mode of carangiform fish and jet propulsion mode of jellyfish together organically. The use of Computational Fluid Dynamics (CFD) and experimental method helps to reveal the effect of caudal fin stiffness and motion parameters on its hydrodynamic forces.Design/methodology/approachFirst, the prototype of BUR was given by mimicking the shape and propulsion mechanism of both carangiform fish and jellyfish. Besides, the kinematics models in both undulation and jet propulsion modes were established. Then, the effects of caudal fin stiffness on its hydrodynamic forces were investigated based on the CFD method. Finally, an experimental set-up was developed to test and verify the effects of the caudal fin stiffness on its hydrodynamic forces under different caudal fin actuation frequency and amplitude.FindingsThe results of this paper demonstrate that BUR with multi-flexible caudal fins combines the hydrodynamic characteristics of undulation and jet propulsion modes. In addition, the caudal fin with medium stiffness can generate larger thrust force and reduce the reactive power.Practical implicationsThis paper implies that robotic fish can be equipped with both undulation and jet propulsion modes to optimize the swimming performance in the future.Originality/valueThis paper provides a BUR with multi-propulsion modes, which has the merits of high propulsion efficiency, high acceleration performance and overcome the head shaken problem effectively.

Planned Destruction of Metal-Core Reactor: Simulation of Catastrophic Accidents and New Experimental Possibilities

A reactor with a destructible core (RIR reactor) generating a pulse with an output of ~1.5 × 1019 fissions and a full width at half maximum of ~2.5 μs was developed and tested at VNIIEF. In the course of investigation, a computational-experimental method for laboratory calibration of the reactor was created and worked out. This method ensures a high accuracy of predicting the energy release in a real experiment with excess reactivity of ~3βeff above prompt criticality. A transportable explosion-proof chamber was also developed, which ensures the safe localization of explosion products of the core of small-sized nuclear devices and charges of high explosives with equivalent mass of up to 100 kg of TNT.

Determination of a tissue-level failure evaluation standard for rat femoral cortical bone utilizing a hybrid computational-experimental method.

Macro-level failure in bone structure could be diagnosed by pain or physical examination. However, diagnosing tissue-level failure in a timely manner is challenging due to the difficulty in observing the interior mechanical environment of bone tissue. Because most fractures begin with tissue-level failure in bone tissue caused by continually applied loading, people attempt to monitor the tissue-level failure of bone and provide corresponding measures to prevent fracture. Many tissue-level mechanical parameters of bone could be predicted or measured; however, the value of the parameter may vary among different specimens belonging to a kind of bone structure even at the same age and anatomical site. These variations cause difficulty in representing tissue-level bone failure. Therefore, determining an appropriate tissue-level failure evaluation standard is necessary to represent tissue-level bone failure. In this study, the yield and failure processes of rat femoral cortical bones were primarily simulated through a hybrid computational-experimental method. Subsequently, the tissue-level strains and the ratio between tissue-level failure and yield strains in cortical bones were predicted. The results indicated that certain differences existed in tissue-level strains; however, slight variations in the ratio were observed among different cortical bones. Therefore, the ratio between tissue-level failure and yield strains for a kind of bone structure could be determined. This ratio may then be regarded as an appropriate tissue-level failure evaluation standard to represent the mechanical status of bone tissue.

MTOR Inhibition Restores Amino Acid Balance in Cells Dependent on Catabolism of Extracellular Protein

Scavenging of extracellular protein via macropinocytosis is an alternative to monomeric amino acid uptake. In pancreatic cancer, macropinocytosis is driven by oncogenic Ras signaling and contributessubstantially to amino acid supply. While Ras signaling promotes scavenging, mTOR signaling suppresses it. Here, we present an integrated experimental-computational method that enables quantitative comparison of protein scavenging rates across cell lines and conditions. Using it, we find that, independently of mTORC1, amino acid scarcity induces protein scavenging and that under such conditions the impact of mTOR signaling on protein scavenging rate is minimal. Nevertheless, mTOR inhibition promotes growth of cells reliant on eating extracellular protein. This growth enhancement depends on mTORC1's canonical function in controlling translation rate: mTOR inhibition slows translation, thereby matching protein synthesis to the limited amino acid supply. Thus, paradoxically, in amino acid-poor conditions the pro-anabolic effects of mTORC1 are functionally opposed to growth.

Minimum miscibility pressure measurement for CO2 and oil using rapid pressure increase method

CO2-enhanced oil recovery (CO2-EOR) is a technique for commercially producing oil from depleted reservoirs with associated benefits of capturing and storing large quantities of CO2. Minimum miscibility pressure (MMP) for gas and oil system is one of the most important factors affecting projecting and developing of EOR CO2 miscible flooding to reach maximum recovery efficiency. Determination of MMP can be performed with computational techniques and experimental methods. The slim tube test (STT), the pressure rising bubble apparatus (RBA), the vanishing interfacial tension (VIT), and recently, developed the sonic response method (SRM) can be considered as the petroleum industry experimental approaches for determination of the MMP for hydrocarbons and CO2. This paper presents a new technique, named rapid pressure increase method (RPI) to measure MMP and investigate the phase behavior of the analyzed fluids. The main principle of the measurement are determination of the relation between pressure increase and reduced volume of binary system and registration of the moment at which derivative of the function is the lowest. This point corresponds to ratio change of pressure increase to reduced volume and is considered as MMP. Determined values fit well with previous work and literature data. This experimental method of MMP is simple, time-saving, and more easily to conduct than other experimental techniques of measurement MMP.