Method For Determination Of Parameters Research Articles

ОПРЕДЕЛЕНИЕ ОПТИМАЛЬНЫХ ПАРАМЕТРОВ ДЕМПФИРОВАНИЯ ЗЕМЛЯНОГО ПОЛОТНА ЖЕЛЕЗНЫХ ДОРОГ В СЕЙСМИЧЕСКИ АКТИВНЫХ РАЙОНАХ

The paper considers a damping layer design for roadbed with parameters that provide safety of railway traffic in seismically dangerous regions. It presents a theoretical study of seismic forces on railway roadbed on the basis of analysis of earthquake influence parameters on stressed and strained state of railway track construction. For the investigations the author has applied methods of multifactorial experimental design. The author has developed a method for determination of optimal parameters for damping depending on main parameters of an earthquake (magnitude, distance from hypocenter, physical and mechanical characteristics of the Earth crust) and geological characteristics of a railway section (capability of layers, deformational and elastic properties of the Earth crust, foundation and roadbed). As a result, the author suggests designs of a damping layer that has a layered-geterogenous compositional structure with given properties. Moreover, he has established a possibility to increase an aseismic stability of railway roadbed by construction of the damping layer with given properties.

Использование вращающейся четвертьволновой фазовой пластины в поляризационно-модуляционных методах определения углов крена и пеленга летательного аппарата

A polarization-modulation method for simultaneous determination of the navigation parameters of the bearing and roll of an aircraft from orthogonally linearly polarized beacon signals is studied. Signals are emitted simultaneously from two spatially separated points in the horizontal plane with known coordinates. On Board the aircraft, the resulting vector signals are received by the onboard receiving antenna, in the path of which a polarizing modulator is installed. A rotating section of a circular waveguide with a quarter-wave phase plate embedded inside is used as a polarizing modulator. The bearing and roll of the aircraft are estimated at the output of a single-channel receiver, respectively, by the amplitudes and phases of the second and fourth harmonics of the polarization modulation frequency contained in the envelope spectrum of the received resulting vector signals.

Inverse Determination Method of Johnson-Cook Model Parameters Based on the Stress State Test of Notched Specimens

Inverse Determination Method of Johnson-Cook Model Parameters Based on the Stress State Test of Notched Specimens

The Machine Learning Embedded Method of Parameters Determination in the Constitutive Models and Potential Applications for Hydrogels

We propose a machine learning embedded method of parameters determination in the constitutional models of hydrogels. It is found that the developed logistic regression-like algorithm for hydrogel swelling allows us to determine the fitting parameters based on known swelling ratio and chemical potential. We also put forward the neural networks-like algorithm, which, by its own property, can converge faster as the layer deepens. We then develop neural networks-like algorithm for hydrogel under uniaxial load for experimental application purpose. Finally, we propose several machine learning embedded potential applications for hydrogels, which would provide directions for machine learning-based hydrogel research.

Key challenges facing the application of the conductivity mass balance method: a case study of the Mississippi River basin

Abstract. The conductivity mass balance (CMB) method has a long history of application to baseflow separation studies. The CMB method uses site-specific and widely available discharge and specific conductance data. However, certain aspects of the method remain unstandardized, including the determination of the applicability of this method for a specific area, minimum data requirements for baseflow separation and the most accurate parameter calculation method. This study collected and analyzed stream discharge and water conductivity data for over 200 stream sites at large spatial (2.77 to 2 915 834 km2 watersheds) and temporal (up to 56 years) scales in the Mississippi River basin. The suitability criteria and key factors influencing the applicability of the CMB method were identified based on an analysis of the spatial distribution of the inverse correlation coefficient between stream discharge and conductivity and the rationality of baseflow separation results. Sensitivity analysis, uncertainty assessment and T test were used to identify the parameter the method was most sensitive to, and the uncertainties of baseflow separation results obtained from different parameter determination methods and various sampling durations were compared. The results indicated that the inverse correlation coefficient between discharge and conductivity can be used to quantitatively determine the applicability of the CMB method, while the CMB method is more applicable in tributaries, headwater reaches, high altitudes and regions with little influence from anthropogenic activities. A minimum of 6-month discharge and conductivity data was found to provide reliable parameters for the CMB method with acceptable errors, and it is recommended that the parameters SCRO and SCBF be determined by the 1st percentile and dynamic 99th percentile methods, respectively. The results of this study can provide an important basis for the standardized treatment of key problems in the application of the CMB.

Energy-Efficient Operation of Massive MIMO in Industrial Internet-of-Things Networks

Massive multiple-input-multiple-output (MIMO) can be effectively applied to the data gathering system of Industrial Internet-of-Things (IIoT) networks. For long-term maintenance of industrial electronic systems with battery-limited IIoT devices, it is essential to increase the energy efficiency (EE) of the system. The high EE should be achieved with ultrareliability and low latency because there are a lot of critical information for the IIoT networks. With this in mind, in this article, we propose high EE operation schemes for the massive MIMO-based IIoT networks. An orthogonal multiple access (OMA) scheme is used and a signal clipping technique is applied to increase the EE of the industrial data gathering system. Clipping distortion for uplink massive MIMO with massive IIoT connectivity is analyzed, and we show that clipping distortion of maximum ratio (MR) processing is directly proportional to the number of service antennas and the number of IIoT devices, while that of zero-forcing (ZF) processing can be reduced as the number of IIoT devices increases. We define the EE metric and derive the closed-form inverses of the EE metric to determine the relevant parameters. Based on the derived closed-form equations, we introduce the EE operation schemes using low-latency parameter determination methods. Simulation results validate the theoretical analysis.

Hirshfeld atom like refinement with alternative electron density partitions.

Hirshfeld atom refinement is one of the most successful methods for the accurate determination of structural parameters for hydrogen atoms from X-ray diffraction data. This work introduces a generalization of the method [generalized atom refinement (GAR)], consisting of the application of various methods of partitioning electron density into atomic contributions. These were tested on three organic structures using the following partitions: Hirshfeld, iterative Hirshfeld, iterative stockholder, minimal basis iterative stockholder and Becke. The effects of partition choice were also compared with those caused by other factors such as quantum chemical methodology, basis set, representation of the crystal field and a combination of these factors. The differences between the partitions were small in terms of R factor (e.g. much smaller than for refinements with different quantum chemistry methods, i.e. Hartree-Fock and coupled cluster) and therefore no single partition was clearly the best in terms of experimental data reconstruction. In the case of structural parameters the differences between the partitions are comparable to those related to the choice of other factors. We have observed the systematic effects of the partition choice on bond lengths and ADP values of polar hydrogen atoms. The bond lengths were also systematically influenced by the choice of electron density calculation methodology. This suggests that GAR-derived structural parameters could be systematically improved by selecting an optimal combination of the partition and quantum chemistry method. The results of the refinements were compared with those of neutron diffraction experiments. This allowed a selection of the most promising partition methods for further optimization of GAR settings, namely the Hirshfeld, iterative stockholder and minimal basis iterative stockholder.

Equivalent model and parameter analysis of non-packed particle damper

A non-packed particle damper (NPPD) is an advantageous passive damping device with a wide frequency band and good robustness. However, its damping mechanism remains unclear, and its application for controlling vibrations in civil engineering structures is being explored. By analysing the particle motion state, this paper proposes a double inertia mass equivalent model (DIMEM) to reflect the interaction between particles. The effect of inertia was introduced in the DIMEM to consider the rolling effect of particles on the damping performance of the NPPD. An electromagnetic vibration table test of a single-storey frame structure with an NPPD was designed and performed. The parameter determination method and applicability of the DIMEM were also evaluated based on experimental and theoretical analyses. Furthermore, the effects of the parameters on the damping performance of the NPPD were systematically analysed. The results confirm that the equivalent model can reflect the damping performance and mechanism of the NPPD. The particle group inertia is an inherent property of the NPPD. With an increase in the ratio of inertance to particle mass, the optimal vibration damping performance deteriorates under harmonic excitation, and the corresponding equivalent connection stiffness gradually increases. The equivalent connection stiffness, additional mass ratio, recovery coefficient, and acceleration normalised collision distance significantly affect the damping performance and mechanism. However, the effects of the equivalent connection damping coefficient and rolling friction coefficient are negligible. The proposed DIMEM and the corresponding parameter analysis can provide an important reference for the application of NPPDs in civil engineering.

Research on extended hypoplastic model and its verification for deposits soil

In order to illustrate the mechanical properties of the coarse-grained deposits soil, a series of large scale triaxial tests of deposits soil from the southwest region of China were carried out. Based on the test data and the basic idea of hypoplasticity, the Wu-Bauer hypoplastic model was extended to describe the mechanical behavior of the deposits soil, so that the constructed equations were induced for developed analysis. The model parameter identification method was proposed for the establishment of extended hypoplastic constitutive model by using improved differential evolution algorithm, which was targeted to find the optimization of the error function between test and theoretical results instructed by the inverse analysis principle. Then, an optimization calculation program was written to achieve the identification of the constitutive model parameters, which showed that the proposed identification method was better than the conventional method of parameter determination. Moreover, the test data and numerical calculation of one-dimensional compression test and triaxial test were compared, which indicated that the extended Wu-Bauer hypoplastic model could reflect the different mechanical properties of the deposits soil under different initial conditions.

General synchroextracting chirplet transform: Application to the rotor rub-impact fault diagnosis

The rub-impact fault between the rotor and the stator surface is a common and serious failure in rotating machinery. The vibration signals acquired during the rotating machinery operation will carry the time-varying characteristics of rapid fluctuating instantaneous frequency (IF) when the healthy condition of rotor system changes. The proposed method is termed as the general synchroextracting chirplet transform which is based on the classical chirplet transform and employs the second-order synchroextracting transform to concentrate the time-frequency representation (TFR). Moreover, an adaptive demodulation parameters determination method based on kurtosis is proposed. The proposed method is non-sensitivity to noise, allows for signal reconstruction, and retains certain processing ability for multicomponent signals. The effectiveness and practical value of the method are verified by the numerical signals and the vibration signals of the heavy oil catalytic cracking machine which has the rotor rub-impact fault.

Si-Ge whiskers for thermoelectric sensors design

The paper deals with studies of thermoelectric properties for Si1-xGex (x=0.01-0.05) whiskers doped with boron during their growth by CVD method. Temperature dependences of the resistance and the Seebeck coefficient for Si1-xGex whiskers were measured in the temperature range 275–550 K. A method for determination of thermoelectric parameters of the whisker was proposed with use of the whisker joints, which allows us to define a ratio of Seebeck coefficient to thermal conductivity a/k. Taking into account the obtained values of Seebeck coefficient, the whisker conductance and estimated values of thermal conductivity, parameter ZT was calculated for the whiskers and consists of 0.15 for T=200oC. The obtained value of ZT is in good coincidence with literature data for hop pressed Si-Ge nanocomposites. The humidity sensor was designed base on Si-Ge whiskers.

Determination of the Effective Electromagnetic Parameters of Complex Building Materials for Numerical Analysis of Wireless Transmission Networks

In this paper, we present the method for determination of effective electromagnetic parameters of complex building materials. By application of the proposed algorithm, it is possible to analyze electromagnetic field distribution for large-scale problems with heterogeneous materials. The two-dimensional numerical model of building components (hollow brick) with periodic boundary conditions was solved using the finite-difference time-domain method (FDTD) and discussed. On this basis, the resultant transmission coefficient was found and then the equivalent relative permeability and electric conductivity of heterogeneous dielectric structures, in the developed homogenization algorithm, were identified. The homogenization of material properties was achieved by performing a multi-variant optimization scheme and finally, selecting optimal electric parameters. Despite the analysis of heterogeneous building materials, the presented algorithm is shown as a tool for the homogenization of complex structures when scattering of a high-frequency electromagnetic field is considered.

Study of colloidal dispersions of gold nanorods using light scattering methods

Five samples of colloidal dispersions of gold nanorods with various aspect ratio were studied using methods based on light scattering. Transmission electron microscopy was used as a reference method. The advantages and disadvantages of the dynamic light scattering and nanoparticle tracking analysis methods for determination of the geometric parameters of nanoparticles, their concentration, monodispersity, as well as for detection of large aggregates and quasispherical impurities were given. It was shown that the method of depolarized dynamic light scattering can be used for determination of the geometric parameters of liquid dispersions of colloidal gold nanorods. Moreover, it was found that the presence of large impurities or particle aggregates in the sample strongly affects the measurement results. The presence of large particles in the dispersion can be determined using dynamic light scattering or nanoparticle tracking analysis methods. The method of dynamic light scattering was also found to be more sensitive to the presence of even a small amount of large impurities or aggregates in the sample. The monodispersity of a liquid dispersion of nanorods can also be estimated by dynamic light scattering and nanoparticle tracking analysis methods, and, comparing to electron microscopy, the measurement results can be considered more statistically reliable due to the analysis of a larger number of particles. It was found that the increase of spherical particles concentration in the composite dispersion of nanospheres and nanorods leads to a decrease in the contribution of the rotational mode in the total scattering intensity. In addition, the concentration of quasispherical impurities in samples of liquid dispersions of colloidal gold nanorods was calculated based on measurements of the depolarization degree of scattered light.

Determination of bacteriophage growth parameters under cultivating conditions.

The determination of bacteriophage growth parameters, such as adsorption constant, latent period, and burst size, is essential for the proper design of bacteriophage production and the estimation of the efficacy of bacteriophage therapy. As they are dependent on the physiological state and cultivation conditions bacteria, they should be preferably determined in a non-invasive way. We propose a method that allows their determination under cultivation conditions. It is based on the cultivation of bacteria in a chemostat, the injection of bacteriophages, and monitoring of their concentration over a certain period. Phage growth parameters are determined by fitting a mathematical model to experimental data. E. coli-T4 system was investigated for various dilution rates covering a broad range of bacteria physiological states. Results were used for a prediction of bacteriophages and bacteria steady-state concentrations in a cellstat. A close match was found when adsorption of bacteriophages to the lysed cells was considered in the cellstat, while this mechanism can be neglected in the chemostat. Trends and values for burst size and latent period were consistent with literature data, demonstrating an increase in the burst size and decrease of the latent period with an increase of bacteria-specific growth rate (from 19 to 81 bacteriophage particles per cell and 89 to 29.8min for a specific growth rate between 0.072 and 0.96h-1, respectively). Adsorption constant also showed an increase with a specific growth rate increase (from 2.8E-10 to 4.0E-09mLmin-1), in contrast to chemostat literature data, probably due to its determination within the bioreactor. The proposed method also allowed estimation of latent period distribution. While its value for high-specific growth rates was determined to be constant of around 6min, an increase of over an order of magnitude was found for the lowest specific growth rate, probably as a consequence of higher variability within bacteria population. KEY POINTS: • A method for determination of phage growth parameters under cultivating conditions was developed. • The method was successfully tested on E. coli and T4 bacteriophage system comparing chemostat and cellstat values. • Adsorption to lysed cells was found to be important for cellstat experiment but can be neglected in the chemostat. • The determined burst size and latent period dependence on the bacterial physiological state was consistent with literature data, while differences were found for adsorption constant. • Latent period distribution significantly increases for low bacteria-specific growth rates.

Study on Dynamic Constitutive Model of Weakly Consolidated Soft Rock in Western China

To obtain the impact mechanical response and establish the dynamic damage constitutive relationship of frozen sandstone at low temperature conditions, the impact test of Cretaceous red sandstone under different temperatures was conducted using a split Hopkinson pressure bar (SHPB) device. According to the characteristics of the stress-strain curves obtained by the test, a constitutive model considering the damage effect, temperature effect, and strain rate effect was established, which was improved by Zhu–Wang–Tang (Z–W–T) constitutive model. It was proved that the fitting curves of constitutive equation were in good agreement with the test curves. The fluctuation amplitude of fitting error was controlled within ±4 MPa. The physical meaning of each parameter of the constitutive model is clear, and most of them are fixed values. The selection range of variable parameters and the related change rules are confirmed, which improves the practicability of constitutive model. The constitutive equation can well describe the nonlinear features of this kind of frozen sandstone under impact loading. It was also found that the constitutive equation was applicable to express the dynamic mechanical properties of rock-like materials such as hard rock, soft rock, frozen soil, raw coal, and concrete. It can be referred to the parameter determination method in this paper to study and determine the parameters, reduce the difficulty of parameter selection, and improve the practicability of the constitutive model and parameters, so as to guide the engineering practice better.

Determination of the through-plane thermal conductivity and specific heat capacity of a Li-ion cylindrical cell

Despite the high popularity of lithium-ion batteries there is still a lack of simple and easily applicable methods for determining the Li-ion cell thermal parameters. Information about the specific heat capacity and thermal conductivity of Li-ion cells is required to ensure appropriate operation of the thermal control system of the Li-ion battery, which prevents battery operation in an unacceptable temperature range. The method presented in this paper allows to simultaneously determine the specific heat capacity and through-plane thermal conductivity of any Li-ion cylindrical cell in a simple and inexpensive way with the help of temperature and heat flux measurements on the cell surface. Moreover, the method allows to estimate the temperature dependence of the thermal parameters under consideration. The applicability of the method is evaluated on the reference sample, whose thermal parameters are close to the thermal parameters of Li-ion cylindrical cells and well known. The slight deviation of the measured values of specific heat capacity and thermal conductivity from the reference values, being less than 0.5% and 3.2%, respectively, for all cases under study, confirms the applicability of the method for determination of the thermal parameters of cylindrical Li-ion cells. Therefore, the method is applied to measure the thermal parameters of 18650-type and 26650-type cylindrical Li-ion cells at different values of temperature and SoC. The uncertainty analysis of the proposed method allows to give recommendations to achieve a high accuracy of thermal parameter determination.

A study of the mechanical structure of the direct roof during the whole process of non-pillar gob-side entry retaining by roof cutting

The non-pillar entry (roadway) retained by roof cutting serves the two adjacent working faces. As compared with the conventional mining roadways, the roadway retained by roof cutting has a longer life cycle and receives more complicated influence from mining. Determining the location where the roof deformation and maximum deformation occur can provide an important basis for roadway support. Here, the direct roof of the roadway is studied by assuming it as an elastic deformation body. The stress features of the direct roof of the gob-side entry retained by roof cutting are analyzed, and the roof deformation is divided into five stages. The stress superposition principle is employed, and the equivalent concentrated load within the roadway is introduced. The mechanical model of the direct roof is established for the whole process of gob-side entry retaining by roof cutting. Next, the calculation formula for the concentration of direct roof at different positions is obtained for the whole process of gob-side entry retaining by roof cutting. The application scope of the calculation formula and the determination method of the key parameters are analyzed. The relationship between direct roof deformation of the roadway and stiffness of the support system is studied. The results show that the direct roof deformation has a symmetrical distribution about the midline. The maximum roof deformation occurs in the middle of the roadway, and it gradually decreases as the coal seam stiffness increases. During the example calculation, the maximum roof deformation is 280 mm for the gob-side entry retaining under primary mining. The measured maximum roof deformation is 320 m, and the error rate is 12.5%. It is then verified that the uniform mechanical model proposed in this study applies to the calculation of direct roof deformation in the gob-side entry retained by roof cutting.

Biosynthesis of benzyl acetate: Optimization of experimental conditions, kinetic modelling and application of alternative methods for parameters determination

In this work, the enzymatic synthesis of benzyl acetate by transesterification between the benzyl alcohol and an acyl donor, has been studied. As first objective the selection of the biocatalyst, acyl donor, stirring, solvent and the enzyme amount, was done and, to do this, three immobilized derivatives of commercial lipases, Lipozyme®TLIM, Novozym®40086 and Novozym®435 were tested, being Novozym®435 the immobilized derivative chosen. Vinyl acetate, 300 rpm and n-heptane were selected as acyl donor, stirring and solvent, respectively.As the main objective, the kinetics of the bioprocess was analysed and a bisubstrate Ping-Pong kinetics was proposed. By using two different procedures, the values of the kinetic parameters: Michaelis constants of both substrates and the specific activity of enzyme have been determined. A good level of agreement between the experimental data and the ones calculated with the kinetic model was obtained.

Performance and process simulation of membrane bioreactor (MBR) treating petrochemical wastewater

Mathematical modelling of biological treatment is an effective tool to predict effluent quality. Model calibration is critical to improve the accuracy of simulation, which is normally carried out by fine-tuning the values of parameters according to the practical data. It indicated that huge amount of practical date will be consumed, and it cannot predict the treatment performance of new wastewater. In this study, the main objective was to investigate the feasibility of application BioWin software coupled with determination of sensitive parameters to predict the treatment performance of membrane biological reactors (MBRs) treating real petrochemical wastewater (PW). Model calibrations, i.e., COD fractions of petrochemical wastewater and kinetic parameters of biomass, were carried out using the respirometry method and the relationship between observed and true growth yield coefficients of the three lab-scale MBRs which were operated under different solid retention time (SRT). All the three MBRs had good organic and ammonium removal, with removal efficiencies higher than 80% and 99.9%, respectively. Simulation using the calibrated model also obtained good fit for effluent COD concentration, effluent nitrate concentration and bioreactor's MLSS concentration of all the three MBRs. The mean absolute percentage errors (MAPE) of the simulation mostly were lower than 22%. The results indicated that it is feasible to using BioWin, incorporated with appropriate determination methods of sensitive parameters, to simulate and monitor the treatment performance of MBR treating petrochemical wastewater. This is more time-saving and effective than fine-tuning values of all parameters. This study provides a valuable reference for simulation of industrial wastewater treatment using BioWin.

Towards Development of a Simple Technique Based on Wavelength Specific Absorption for Quality Measurement of Flowing Water

Water quality assessment has undeniable value for humanity’s well-being. Despite that, most of the existing techniques struggle to measure the quality of running water due to costly infrastructure or large evaluation time. Recently, quality measurement has been demonstrated using spectrum analysis. However, these modern systems need complicated signal processing algorithms and high processor capabilities for decision making, have elaborate optical assemblies and sizable power requirement making them bulky and expensive to operate. Thus, a refined technique with simplified implementation, low cost, and reliable long-time operation is essential to address this challenge. We present, for the first time to our knowledge, a holistic approach towards a simple and rapid method for determination of water quality parameters in flowing water. This is based on the selection of characteristic wavelengths for the parameters considered and usage of narrowband LEDs as the inspection light source. Thereby incorporating the benefits of optical sensing such as electromagnetic immunity, selectivity, sensitivity, etc. The specific wavelengths of 560nm, 860nm, and 635nm have been demonstrated to have a dominant effect due to pH, turbidity, and total dissolved solids (TDS) respectively, from regression analysis. Using only these wavelengths, an evaluation system capable of determining the light absorption after passing through water has been designed and developed. The obtained optical responses are subsequently related to water parameters, specifically pH, TDS, and turbidity. Experiments were performed to evaluate samples and then validate this technique against standard instruments for both flowing and sampled water setups. It is shown from the measurement results that pH, turbidity, and TDS have linear regression coefficients of 0.9773, 0.9617, 0.8271 and 0.9691, 0.9729, 0.76 for flowing and sampled water arrangements, respectively.