Actual Parameter Values Research Articles

Variational approach for mechatronic tolerancing: application to a DC motor

Having an increasingly complex set of inter-relations between several components from different domains, mechatronic systems become more and more complex. The behavior of such systems depends on the values of their parameters and variables. A deviation of these values from their expected values affects the overall functioning of the system, degrades the system quality, and may be a significant threat to safety. To reach an expected quality level, the deviations between actual and target values of parameters should be within specified tolerances. For this, two extreme limits (i.e. upper and lower bounds) of these values must be wisely determined. It is also important to know the impact of parameters deviations on system behavior. Furthermore, the margin of variables should be controlled to evaluate system performance with respect to the specifications, requirements and user needs. This paper describes a methodology based on a variational approach combined with Worst-Case Analysis and Monte Carlo Simulation to determine the impact of the parameters variation on the system behavior. It helps designers to analyze tolerances of mechatronic systems. Our proposed methodology is illustrated with a DC motor case study. The results show that the developed method provides a new way for mechatronic tolerancing.

Optimal regenerative braking torque of permanent-magnet synchronous motor in electric vehicles

This study investigated a method to determine the optimal regenerative braking torque with maximum energy recovery at given speed, which is essential for the regenerative braking control of electric vehicles. The method is based on the loss modelling of a permanent-magnet synchronous motor (PMSM) system, which consists of electric motor and inverter. The system-loss model is established based on a PMSM mathematical model including iron loss and is used to derive the optimal regenerative braking torque symbolic formula. In addition, the parameter sensitivity of the optimal regenerative braking torque is analysed and a method for online parameter identification is used to obtain the actual parameter values in real time. Thus, the accuracy and adaptability of the optimal regenerative braking torque during the motor-operation process is improved. The analysis results are validated through simulation and bench tests.

Optimal regenerative braking torque of permanent-magnet synchronous motor in electric vehicles

This study investigated a method to determine the optimal regenerative braking torque with maximum energy recovery at given speed, which is essential for the regenerative braking control of electric vehicles. The method is based on the loss modelling of a permanent-magnet synchronous motor (PMSM) system, which consists of electric motor and inverter. The system-loss model is established based on a PMSM mathematical model including iron loss and is used to derive the optimal regenerative braking torque symbolic formula. In addition, the parameter sensitivity of the optimal regenerative braking torque is analysed and a method for online parameter identification is used to obtain the actual parameter values in real time. Thus, the accuracy and adaptability of the optimal regenerative braking torque during the motor-operation process is improved. The analysis results are validated through simulation and bench tests.

Water quality monitoring at a virtual watershed monitoring station using a modified deep extreme learning machine

ABSTRACTA new deep extreme learning machine (ELM) model is developed to predict water temperature and conductivity at a virtual monitoring station. Based on previous research, a modified ELM auto-encoder is developed to extract more robust invariance among the water quality data. A weighted ELM that takes seasonal variation as the basis of weighting is used to predict the actual value of water quality parameters at sites which only have historical data and no longer generate new data. The performance of the proposed model is validated against the monthly data from eight monitoring stations on the Zengwen River, Taiwan (2002–2017). Based on root mean square error, mean absolute error, mean absolute percentage error and correlation coefficient, the experimental results show that the new model is better than the other classical spatial interpolation methods.

Mesoscale numerical modeling of the boundary atmospheric layer adapted to the north-western Black Sea region. Part 1. Mathematical problem formulation

The article presents a complete mathematical formulation of the problem of the boundary layer of the atmosphere and the interacting surface layers of the soil with the active layer of the sea adapted to the North-Western Black Sea Region through the inclusion of the coastline shape, relief elevation angles and climatic characteristics of soil moisture. The numerical model is a three-dimensional, unsteady, hydrostatic model with one- or two-parameter closure. The paper presents a detailed description of the applied sub-grid processes parameterizations such as cloudiness in the lower tier, flows of short- and long-wave radiation throughout thickness of the boundary layer and near the Earth, antigradient migration for basic meteorological variables in the presence of neutral or weakly stable stratification, components of water, heat and radiation balance, phase transitions of moisture in the atmosphere, and different parameterizations of turbulent processes used in the model. The possibilities of the model include description of neutral and stable boundary layers with consideration of the kinetic energy of vertical velocity fluctuations instead of the kinetic energy of longitudinal and transverse velocity fluctuations. Identification of the type of the boundary layer at a particular point in time is estimated using values of the Richardson number. In addition, in case of convective conditions presence, parameterization of dry convection and wet-convective adaptation may be implemented. At the boundaries of "free boundary layer – surface or near-water layer of air, air-soil and air-water" certain bonding conditions are to be set to ensure continuity of meteorological parameters or their flows. On the upper boundary of the free boundary layer actual values of meteorological parameters and necessary parameters, or corresponding values from the global atmospheric model are to set. At the lower boundary of the deep soil layer the invariance of the vertical temperature gradient of the active layer of the sea – the value of temperature which is equal to the value of the latter according to its climatic values in the considered season of the year is to be set. The presented model is the first approximation in numerical modeling of the boundary layer over the adapted territory and is designed for studying the thermodynamic structure of the boundary layer of the adapted territory, as well as for identifying the breeze effects over the terrain.

Machinability and Energy Efficiency in Micro-EDM Milling of Zirconium Boride Reinforced with Silicon Carbide Fibers.

Several types of advanced materials have been developed to be applied in many industrial application fields to satisfy the high performance required. Despite this, research and development of process suited to machine are still limited. Due to the high mechanical properties, advanced materials are often considered as difficult to cut. For this reason, EDM (Electrical Discharge Machining) can be defined as a good option for the machining of micro components made of difficult to cut electrically conductive materials. This paper presents an investigation on the applicability of the EDM process to machine ZrB2 reinforced by SiC fibers, with assessment of process performance and energy efficiency. Different fractions of the additive SiC fibers were taken into account to evaluate the stability and repeatability of the process. Circular pocket features were machined by using a micro-EDM machine and the results from different process parameters combinations were analyzed with respect to material removal, electrode wear and cavity surface quality. Discharges data were collected and characterized to define the actual values of process parameters (peak current, pulse duration and energy per discharge). The characteristics of the pulses were used to evaluate the machinability and to investigate the energy efficiency of the process. The main process performance indicators were calculated as a function of the number of occurred discharges and the energy of a single discharge. The results show interesting aspects related to the process from both the performances and the removal mechanism point of view.

Modeling Interference-Free Neuron Spikes With Optogenetic Stimulation

This paper predicts the ability to externally control the firing times of a cortical neuron whose behavior follows the Izhikevich neuron model. The Izhikevich neuron model provides an efficient and biologically plausible method to track a cortical neuron's membrane potential and its firing times. The external control is a simple optogenetic model represented by an illumination source that stimulates a saturating or decaying membrane current. This paper considers firing frequencies that are sufficiently low for the membrane potential to return to its resting potential after it fires. The time required for the neuron to charge and for the neuron to recover to the resting potential are numerically fitted to functions of the Izhikevich neuron model parameters and the peak input current. Results show that simple functions of the model parameters and maximum input current can be used to predict the charging and recovery times, even when there are deviations in the actual parameter values. Furthermore, the predictions lead to lower bounds on the firing frequency that can be achieved without significant distortion.

Curvilinear Stress-Strain Relationship for Concrete of EN-2 Regulation in the ZI Method and the Calculation of Beam Strength

The article illustrates the possibilities of the practical application of the ZI method [1 and 2] when calculating the strength of reinforced concrete beams. The article presents variants of description of the EN-2 regulation curvilinear diagram for concrete with reliability of 50 % by the ZI method with reliability of 50 %, 95 % and ~100 %. The article demonstrates how, when calculating the strength of normally and abundantly reinforced concrete beams by the ZI method, it is possible to do without the calculation of the limit value of the thickness of the concrete layer of the beam compression zone. This is important in the case of the calculation of the strength of abundantly reinforced beams. The method for calculating the strength of abundantly reinforced beams has been improved. When calculating strength, we also obtain actual values of stress-strain parameters at the crack. The tables provide data supporting the proposed innovations and facilitating calculations.

Nominal and Actual Values of Inductor and Capacitor Parameters at High Frequencies

Coil inductance and capacitor capacitance depend on overall dimensions, structure, and ambient factors. They do not vary with frequency. Reactive component impedance is determined by inductance or capacitance respectively, if active resistance is not considered. This is true for the frequencies which are significantly lower than the self-resonant frequency of the component. Parasitic parameters contribution increases on approaching the self-resonant frequency. Therefore, the componentʼs actual inductance and actual capacitance on operating frequency are defined. They are provided by manufacturers and differ from the nominal values. The actual values provide more accurate impedance of components near the considered frequency. Significant deviation from the considered frequency can cause impedance mismatch even more than the nominal values can provide. Frequency response of the high-frequency circuits such as analog filters and impedance match networks are determined by components impedance, not the nominal values. Thus, calculated values must be close to the actual values. The purpose of this article is to justify actual values application instead of nominal values.

Laboratory improvement and field assessment of Volumetric design method based on multi-point Supported skeleton for asphalt mixtures (V-S method)

The V-S method was proposed to design asphalt mixtures with satisfactory high-temperature stability. However, the design procedures in the laboratory are different from the field compaction condition since the degradation rate δcc of coarse aggregates is determined by 100 Marshall compactions (MCs). In this study, the V-S method was improved in the laboratory and was subsequently assessed in the field. In the laboratory, the MC, roller compaction by wheel tracking, and Superpave gyratory compaction (SGC) were evaluated for the degradation rate δcc with water binder instead of asphalt binder. Results show the SGC produces less degraded coarse aggregates, so the degradation rate δcc should be determined by 100 SGCs instead of 100 MCs. Subsequently, the improved V-S method was applied for the upper surface course of a freeway, which was surveyed and cored for rutting after approximately 3-year service. In conclusion, with the improved V-S method, asphalt mixtures possess narrower deviations between the design and actual values of volume parameters in the laboratory and satisfactory high-temperature stability in the field.

Shear-dependency of the predicted ideal hematocrit.

The ideal hematocrit is the hematocrit (Hct) value resulting in the highest value of Hct/viscosity (h/η) ratio and can thus be predicted from viscometric measurements with the use of equations such as Quemada's one which yield the determination of the bell-shaped curve of h/η as a function of Hct. In a series of recent papers we applied this approach to various populations, using viscometry at high shear rate (1000 s-1). However the shape of this curve has been reported to be dependent on the shear rate, resulting in a right-shift in this top value when Hct increase. We present here in 11 young recreative athletes the evolution of the predicted top of the h/η curve and optimal theoretical Hct and the discrepancy between theoretical and optimal values over the range of shear rates 1 to 6000 s-1. Results show that the predicted optimal value of both h/η and Hct increases when shear rate increases and that the discrepancy between predicted laquooptimalraquo and actual values decreases and becomes almost asymptotic at very high shear (500 s-1). It is minimal at 2720 s-1. The correlation between predicted laquooptimalraquo and actual values of both parameters describes the same evolution. Therefore, it is better for assessing h/η and its agreement with theoretical values, and for determining the theoretical ideal hematocrit, to measure blood viscosity at shear rates equal or superior to 500 s-1.

Hydrophobicity, Freezing Delay, and Morphology of Laser-Treated Aluminum Surfaces.

Until recently, superhydrophobicity was considered as a hint to predict surface icephobicity, an association of concepts that is by no means universal and that has been proven to depend on different experimental factors and material properties, including the actual morphology and chemical state of surfaces. This work presents a systematic study of the wetting and freezing properties of aluminum Al6061, a common material widely used in aviation, after being subjected to nanosecond pulsed IR laser treatments to modify its surface roughness and morphology. All treated samples, independent of their surface finishing state, presented initially an unstable hydrophilic wetting behavior that naturally evolved with time to reach hydrophobicity or even superhydrophobicity. To stabilize the surface state and to bestow the samples with a permanent and stable hydrophobic character, laser-treated surfaces were covered with a thin layer of CF x prepared by plasma-enhanced chemical vapor deposition. A systematic comparison between freezing delay (FD) and wetting properties of water droplets onto these plasma-/polymer-modified laser-treated surfaces that, under conditions where a heterogeneous nucleation mechanism prevails, surface morphology rather than the actual value of the surface roughness parameter the key feature for long FD times. In particular, it is found that surface morphologies rendering a Cassie-Baxter wetting regime longer FDs than those characterized by a Wenzel-like wetting state. It is that laser treatment, with or without additional coverage with thin CF x coatings, affects wetting and ice formation behaviors and might be an efficient procedure to mitigate icing problems on metal surfaces.

Full 16-parametric model of calibration processes and direct measurement of parameters of four-poles

A complete mathematical model for measuring the parameters of the scattering matrix for a measurement object [Sx] in the form of a four-port network is developed, in which the mathematical model of the eight-port error is described by 16 parameters of the scattering matrix [E]. In addition, in comparison with the 12-parameter model of the eight-port error network, four parameters are included, which allow taking into account leaks, parasitic transmissions of microwave modules under study (microwave microassemblies). Due to the use of matrix analysis methods, the equations in matrix form are obtained that connect the matrices of the measurement object [Sи] and the actual values of the matrix parameters [Sx], with the aim of enabling the solution of these equations instead of the scattering matrix [E] to use a transmition matrix [T] in the form of cellular matrices [Taa], [Tab], [Tba], [Tbb].

Territorial Technosphere as Managed Dynamic System

The territorial technosphere is a dynamic system described by a system of differential equations. The initial data of these equations take into account the conditions of normal functioning of the territorial technosphere and emergency situations. Changing the parameters of the impact of the technosphere allows you to influence the quality of the environment and to maintain it in a stable state. An effective mechanism for controlling the territorial technosphere as a dynamic system should be the elimination of inoperable States using: the formation of a set of informative parameters; control and registration of values of informative parameters; creation of a database of normative and actual values of informative parameters, formation of control actions.

Pump-probe optical response of semiconductor quantum dot–metal nanoparticle hybrids

We study optical effects in a hybrid system composed of a semiconductor quantum dot (SQD) and a spherical metal nanoparticle (MNP) that interacts with a weak probe and a strong pump electromagnetic field. We use modified nonlinear density matrix equations for the description of the optical properties of the system and calculate, numerically, the first-order susceptibilities of the SQD, the MNP, and the total hybrid nanostructure of the probe field in the presence of the pump field. We investigate the dependence of the probe absorption and dispersion spectra of the SQD, the MNP, and the total nanostructure on the interparticle distance and the detuning of the pump field, and stress the influence of the MNP contribution to the total optical response. The results we find are explained according to the theory of two distinct metastates, which constitute conjugations of the SQD excitonic and the MNP plasmonic excitations. We also show that the optical response strongly depends on the actual values of the SQD material parameters.

Territorial Technosphere as Managed Dynamic System

The territorial technosphere is a dynamic system described by a system of differential equations. The initial data of these equations take into account the conditions of normal functioning of the territorial technosphere and emergency situations. Changing the parameters of the impact of the technosphere allows you to influence the quality of the environment and to maintain it in a stable state. An effective mechanism for controlling the territorial technosphere as a dynamic system should be the elimination of inoperable States using: the formation of a set of informative parameters; control and registration of values of informative parameters; creation of a database of normative and actual values of informative parameters, formation of control actions.

DEVELOPMENT OF A METHOD FOR ON-LINE MONITORING OF THE PRODUCTION WELLS BOTTOMHOLE ZONE (ON THE EXAMPLE OF YAMASHNEFT OGPD DEPOSITS)

At present, the question of choosing the right approach to hydrodynamic studies and the subsequent processing of the data obtained is highly relevant. The quality of the research and, accordingly, data processing is influenced by various factors, such as the lithological composition of the rocks, their density, mechanical stresses in the rock, the hydrodynamic effect of cracks, the filtration motion of liquids, the distribution of pressure and temperature in the formation. Deposits of Yamashneft OGPD are at a late stage of development, most wells are stripped. All of the above mentioned factors can affect the results of the treatment of the pressure buildup curve (PBC), which often differ from the actual values of the bottomhole zone parameters of the formation, which indicates an incorrect approach to research (recovery time) and selection of the treatment method. The issues of obtaining reliable information at a late stage of development are of particular importance, since it is on their basis such important technological and economic decisions are taken as the disconnection of the waterlogged reservoirs and stripped wells, and technological measures for increasing the oil recovery factor are planned and implemented. When carrying out hydrodynamic studies of wells and interpreting the obtained data, it is necessary to take into account the structure of the investigated formation, the features of the pore space, the geological and physical characteristics, which will allow a correct calculation of the porosity and permeability properties. So, the geological and physical data of operational objects were generalized, the dependence of the influence of the properties of the developed formation and the physico-chemical parameters of the extracted products on the shape of the PBC was made, the application of the adapted methods of interpreting the curves depending on the given development conditions was proposed, a method of studying wells allowing to combine the process of swabbing with the study was presented.

Calculation of Kinetic Parameters of the Thermal Decomposition of Residual Waste of Coniferous Species: Cedrus Deodara

Abstract This paper deals with pyrolysis decomposition of Cedrus deodara leaves with the help of thermogravimetric analysis (TGA). Experiments are performed in the presence of inert atmosphere of nitrogen. Experiments are conducted at three different heating rates of 5 °C∙min-1, 10 °C∙min-1 and 15 °C∙min-1 within temperature range of 35 °C to 700 °C. Arrhenius parameters such as activation energy and frequency factor are estimated by Flynn Wall and Ozawa (FWO), Kissinger-Akahira-Sonuse (KAS) and Kissinger. The activation energy and frequency factor calculated by using Kissinger method are 67.63 kJ∙mol-1 and 15.06 . 104 min-1 respectively; whereas the averaged values of the same parameters through FWO and KAS methods are 89.59 kJ∙mol-1 and 84.748 kJ∙mol-1, 17.27 . 108 min-1 and 62.13 . 107 min-1 respectively. Results obtained through Kissinger method represent the actual values of kinetic parameters. Conversely, FWO and KAS methods reflect the apparent values of kinetic parameters, as they are highly influenced by the overlapping of competitive reactions occur during pyrolysis.

A probabilistic model to describe the interference produced by VSAT MF‐TDMA networks

SummaryThis paper develops a mathematical model to describe the statistical behavior of the interference produced by VSAT/MF‐TDMA networks. The model is used to assess the interference produced by the uplinks of a VSAT/MF‐TDMA network into links of a network that uses a neighboring satellite. In the proposed model, analytical expressions were developed to account for the effects of variations in transmitting powers, antenna sizes, and transmitting antenna pointing errors. The earth station locations are modeled by a 2‐dimensional Poisson point process. The model is general enough to accommodate other types of point processes and can be applied to situations involving service areas containing multiple types of earth station geographical distribution. Numerical results obtained with the proposed model are compared with those based on the actual parameter values (eg, earth station locations, antenna sizes, and transmitting powers), which were provided by a Brazilian satellite operator.

Poroperm properties of reservoir rocks at Kachalivske oil and gas condensate field

The results of laboratory, geological and geophysical research methods in Visean and Tournaisian reservoir rocks with complex type deposits of Kachalivske oil and gas condensate feild were analysed. The connection of structural and lithological characteristics with geophysical parameters was substantiated. In some cases, in the Visean and Tournaisian deposits, the multicomponent composition of the rock matrix affects the actual value of geophysical parameter, leading to erroneous conclusions about the reservoir, the nature of the saturation and depth of occurrence. As a result of the statistical processing of experimental laboratory studies and geophysical studies of wells in the Visean and Tournaisian deposits at Kachalivske oil and gas condensate feild, petrophysical models of reservoir rocks were developed allowing reliable determination of poroperm properties of such reservoir rocks. The developed models can be used both for determination the reservoir rock parameters and for quick interpretation of geophysical research results.