Non-ideal Parameters Research Articles

Интермодуляционные искажения в ключевых генераторах класса D с резистивной нагрузкой в режимах с переключением тока и мостовом

The article is a continuation of the topic consideration of reverse intermodulation distortions analysis in class D switching generators with a resistive load. Similar to the approach used for the voltage-switched circuit in the previous authors work, a theoretical analysis of the reverse intermodulation distortion in class D current-switched circuit and in the bridge circuit is carried out. For both configurations, expressions for the output spectrum are written and the dependences of intermodulation distortion on non-ideal element parameters and operating modes are considered. A comparison of all three configurations of switching generators with a resistive load, while ensuring the intermodulation distortion level not exceeding minus 70 dB, showed that the circuit with voltage switching imposes the most stringent requirements for all influencing parameters. In it, the variation in the saturation resistance of the switches should not exceed 20%, and the total switches saturation time deviation in any combination should not exceed 0.01, which is 2% of 0.5T (from Pi). The current switching circuit allows a similar switches saturation time deviation, but the distortions in it do not depend on the switches saturation resistances difference. The switching bridge circuit allows for a 70% difference in switches saturation resistance. The permissible total saturation time deviation depends on the mode of operation and is 2.4% for overlapping and 18% for undercovering. The study allows developers of highly efficient switching generators to take into account one more parameter - resistance to induced electromagnetic radiation, in addition to the generally accepted achievable efficiency values, current and voltage crest factors, and resistance to load mismatch.

Analog interface based on capacitance multiplier for capacitive sensors and application to evaluate the quality of oils

<abstract><p>Currently, interdigital capacitive (IDC) sensors are widely used in science, industry and technology. To measure the changes in capacitance in these sensors, many methods such as differentiation, phase delay between two signals, capacitor charging/discharging, oscillators and switching circuits have been proposed. These techniques often use high frequencies and high complexity to measure small capacitance changes of fF or aF with high sensitivity. An analog interface based on a capacitance multiplier for capacitive sensors is presented. This study includes analysis of the interface error factors, such as the error due to the components of the capacitance multiplier, parasitic capacitances, transient effects and non-ideal parameters of OpAmp. A design approach based on an IDC sensor to measure the quality of edible oils is presented and implemented. The quality relates to the total polar compounds (TPC) and consequently to relative electrical permittivity <inline-formula><tex-math id="M1">\begin{document}$ {\varepsilon }_{r} $\end{document}</tex-math></inline-formula> of the oils. A measurement system has been implemented to measure the capacitance of the IDC sensor, which depended on <inline-formula><tex-math id="M2">\begin{document}$ {\varepsilon }_{r} $\end{document}</tex-math></inline-formula>. The simulation and experimental results showed that, for a capacitance multiplication factor equal to 1000, changes of 3.3 µs/100 fF can be achieved with an acceptable level of noise, which can be easily measured by a microcontroller.</p></abstract>

Shock wave solution for the planar, cylindrically, and spherically symmetric flows of non-ideal relaxing gas

In the present article, we investigate one-dimensional non-ideal relaxing gas to study solution of shocks for planar and non-planar flows, more specifically cylindrically symmetric, and spherically symmetric flows. The analytic solution of the problem is determined in the characteristic plane. It signifies that linear solution in this plane reveals non-linear behavior in the physical plane. Also, the condition of shock formation has been determined by analyzing the growth and deterioration of shocks using transport equations. It is observed that nature of the solution completely depends upon relaxing gas parameters and non-idealness. All computations are done using computational package MATHEMATICA. • Shock wave solution to the non-ideal relaxing gasdynamic system is studied. • The condition of shock formation is determined. • The growth and deterioration of shocks is discussed. • Impact of relaxing gas and non-ideal parameters on the evolution of shock is studied.

Experimental and computational investigation of solid suspension and gas dispersion in a stirred vessel

Hydrodynamics and residence time distribution (RTD) of fluid elements are key parameters to characterize the performance of stirred vessel. They are governed by geometric and operating parameters of the stirred vessel (SV). In the present work, the performance of the stirred vessel is studied using computational fluid dynamics (CFD) with realizable k−ε turbulence model. The multiple reference frame and sliding mesh approach are used for impeller motion. The solid–liquid flow and associated solid suspension characteristics are predicted using the two-fluid model (Euler–Granular). The performance of the stirred vessel is characterized by analyzing predicted velocity magnitude, solid concentration (suspension quality), and solid sedimentation. This is compared with the stirred vessel with draft tube baffle configuration (three inner baffles and six outer baffles). The recirculatory flow in draft tube SV helps to achieve uniform suspension and less sedimentation. Further, CFD simulations are carried out in Lagrangian way to analyze chaotic mixing among fluid elements. This is qualitatively analyzed using Poincaré map and quantitatively evaluated using Shannon entropy. The extent of chaotic mixing in draft tube SV is found to be high. The performance of the stirred vessel is further investigated through stimulus–response tracer techniques (RTD) to detect design flaws such as bypass and dead zones. This is analyzed for a wide range of operating parameters and identified optimum conditions (flow rate, impeller speed) for the operation of SV. The four different outlet pipe locations are chosen in SV. The bypass and dead volume are analyzed accordingly, and an optimum outlet pipe location is found. To reduce the extent of non-ideal parameters, three different gas source locations are considered and gases are dispersed in the form of bubbles. The gas dispersion at optimum gas injection point is found to reduce non-ideal parameters and improve the design of stirred vessel.

Similarity solution for isothermal flow behind the magnetogasdynamic cylindrical shock wave in a rotating non-ideal gas with the effect of the gravitational field

In this paper, we investigate a system of quasilinear hyperbolic partial differential equations, which describes the propagation of cylindrical shock waves in a rotating non-ideal gas with the effects of the gravitational field and the axial magnetic field. It is assumed that the flow is isothermal. The Lie group of transformations is used to generate the self-similar solutions of the considered problem in the medium of uniform density. The axial and azimuthal components of fluid velocity and magnetic field are supposed to be varying. We find the generators of the Lie group of transformations by employing the invariant surface criteria. We discovered four alternative solutions by selecting the arbitrary constants indicated in the generators' phrase. Only in three out of these four cases, the self-similar solutions exist. Two types of shock paths appear while solving the above cases. The power-law shock path appears in the first and third cases, while the exponential-law shock path appears in the second case. To find self-similar solutions, these cases have been solved numerically. We graphically show the distributions of flow variables behind the shock wave so that we can observe the effect on flow variables of the various values of the non-ideal parameter, Alfvén Mach number, adiabatic exponent, gravitational parameter, and ambient azimuthal velocity exponent. For the computational task, we used “MATLAB” software.

Integrated biomarker response index as an ally in the observation of metabolic biomarkers in muscle of Astyanax lacustris exposed to thermal variation

Temperature is an important factor that conditions the physiological responses of fish, generating a stressful condition when in non-ideal parameters. Thus, the objective was to evaluate metabolic aspects in the muscle of fish Astyanax lacustris submitted to thermal shock. The specimens were subjected to 2, 6, 12, 24, 48, and 96 h of exposure to 15 °C and 31 1 °C, with their respective controls 23 °C. At 15 °C there was a reduction in glycogenolysis in the initial periods indicated by changes in glycogen phosphorylase (GP), pyruvate and lactate. Subsequently, there was an increase in GP activity, pyruvate levels and hexokinase activity in the next time periods, suggesting an increase in energy demand. At 31 °C there was observed low need for the protein metabolism, indicated by reduction in the activity of aspartate aminotransferase and alanine aminotransferase. At 15 °C, initial periods show an increase in glutathione reductase activity and an increase in carbonylated protein levels, indicating induction of oxidative stress for muscle. At 31 °C, there was a punctual increase in reduced glutathione levels at 24 h. In addition, the integrated biomarker response index proved to be a good ally in the evaluation of a set of biomarkers, corroborating the results observed by the biomarkers individually. Thus, it is possible to conclude that the acute thermal shock affects the metabolism of A. lacustris muscle, which undergoes rearrangements to deal with temperature, where 15 °C is more stressful than 31 °C.

Similarity solution using group theoretic method for unsteady flow behind shock wave in a self-gravitating dusty gas

In this article, the similarity solution using the Lie group theoretic method for unsteady isothermal and adiabatic flows behind cylindrical or spherical shock wave in a mixture of self-gravitating real gas and small solid particles is discussed. The Lie group theoretic method gives out different cases, i.e., exponential law and power-law shock paths. The similarity solution exists only when the shock path varies according to an exponential law. The dispersal of the flow variables with the variations of the solid particles’ mass concentration in the mixture kp, gravitational parameter g0, the ratio of the density of solid particles to the initial density of the gas μ1, non-idealness parameter b¯ and the geometry index ν are discussed graphically. It is found that an increase in the value of μ1 or g0 or ν leads to an increase in the shock strength, but the shock wave decay with an increase in b¯. A comparison between the solutions for cylindrical and spherical symmetry, and for adiabatic and isothermal flows is also made.

Microwave photonic multiform microwave frequency shift keying signal generator.

A photonic approach to realizing multiform microwave frequency shift keying (FSK) signal generation is proposed and demonstrated. In the scheme, a commercial dual-polarization quadrature phase shift keying modulator (DP-QPSKM) is employed to generate two orthogonally-polarized signals containing specific optical sidebands, and a subsequent Sagnac loop structure govern the interference results of these two signals. From a theoretical analysis, when the modulators are properly biased, microwave FSK signal with fixed double relationship or flexibly tunable subcarrier frequencies can be obtained, and high frequency multiplication can be realized in the meantime. Furthermore, a photonic-optimized coherent demodulation structure is designed to recover the binary coding data, which can effectively avoid the electronic bottleneck. Simulation has been performed to investigate the mechanism and the discussions about the robustness to non-ideal parameters including DC bias, phase shift and polarization angle are also given. In the proof-of-concept experiment, microwave FSK signal with subcarrier frequencies of 2/4, 2.2/3.8, 2.4/3.6, 2.6/3.4, 2.8/3.2 GHz are generated, and the correct binary coding data is successfully recovered with the aid of simulation platform. The simulation and experimental results can verify the feasibility of the proposed multiform microwave FSK signal generator, which may find applications in modern radar and communication systems.

Photoionization of helium atom embedded in classical non-ideal plasma at high non-relativistic photon energies

The effects of the non-ideality (NI) of classical plasmas on the photoionization of helium atoms at high non-relativistic photon energies are investigated within the framework of the dipole approximation. Screened interaction in non-ideal plasmas is represented by an effective potential, deduced from a solution of Bogolyubov's hierarchy equations on discarding the effects of quantum degeneracy. A highly correlated wave function consisting of 715 terms for the ground state of helium has been used to evaluate the dipole matrix element. Changes in the asymptotic cross sections of single, double, and total photoionizations due to varying NI of plasmas have been investigated in detail. Particular emphasis is made to study the changes in the asymptotic ratio of the double-to-single photoionization cross section caused by the variation of non-ideality parameter in a wide range. It is found that increasing plasma NI makes the feasibility of occurrence of double photoionization to broaden.

Propagation of shock wave in a non-ideal dusty gas in rotating medium using Lie group theoretic method: Isothermal flow

This paper concerns with the similarity solutions using Lie group theoretic method for one-dimensional unsteady isothermal flow behind the shock wave in the mixture of non-ideal gas and small solid particles in rotating medium. Group theoretic technique brings the different possible cases of potential solutions with the power law, particular case of power law and exponential law shock paths with the different choices of constants present in the generators of the Lie group of transformations. Similarity solutions for non-ideal dusty gas (a mixture of non-ideal gas and small solid dust particles) exist if the density of the ambient medium is constant. Solutions are obtained for both exponential law and power law shock paths. The effects of the variation of the physical parameters on the flow variables distribution behind the shock wave front, and on the shock are discussed. The shock strength increases with an increase in the ratio of the specific heat of the solid particles to the specific heat of the gas at constant volume [Formula: see text], the initial azimuthal velocity variation index [Formula: see text], and the ratio of the density of solid particles to the initial density of the gas [Formula: see text]. The shock wave decays with an increase in the value of gas non-idealness parameter [Formula: see text].

Performance-guaranteed adaptive self-healing control for wastewater treatment processes

This paper investigates the performance-guaranteed adaptive self-healing control for wastewater treatment processes (WWTPs), in which the non-ideal actuator, i.e., the actuator suffering from faults and constraints is considered. Firstly, an error conversion dynamic model based on a new prespecified-time performance function is presented to guarantee that the tracking error is quickly maintained in the user-defined area regardless of the occurrence of actuator faults and constraints. Secondly, a novel smooth approximation function is constructed to imitate the non-smooth characteristics of actuator constraints. Thirdly, the unknown bounds of non-ideal actuator parameters are estimated online in place of parameters themselves. Meanwhile, the lumped disturbances induced by the external disturbance and the fuzzy approximation error are suppressed via H∞ control theory. In addition, the stability analysis is carried out by the Lyapunov stability criterion to guarantee that all closed-loop system signals are bounded. Finally, comparative simulation results demonstrate that the proposed method has the superiorities in terms of preferable dynamic tracking performance with fast transient convergence, strong robustness and performance recovery under non-ideal actuator.

Soft-Switched DC-DC Converter With T-Type Auxiliary Circuit for Vehicular Applications

This article proposed an isolated full-bridge dc&#x2013;dc converter (IFBDC) with T-type auxiliary circuit for vehicular applications. The proposed IFBDC operated with modified pulse width modulation (MPWM) ensured the zero voltage switching turn-<small>on</small> for the active switches of the converter during full-battery charging range. By using MPWM the value of the auxiliary and series inductance of the IFBDC is reduced as compared to phase-shift modulation operated converter. The proposed configuration also pursue the low-temperature rise during the battery charging process. The analysis of the converter is presented in ideal and nonideal parameters. Later, the analysis is verified on MATLAB/ Simulation and PSIM. To validate the results of simulation a 500-W, 80-kHz experimental prototype is developed and gating signals are given by using TMS320F28379D DSP controller.

Nonideal self-gravity and cosmology: Importance of correlations in the dynamics of the large-scale structures of the Universe

Aims. Inspired by the statistical mechanics of an ensemble of interacting particles (BBGKY hierarchy), we propose to account for small-scale inhomogeneities in self-gravitating astrophysical fluids by deriving a nonideal virial theorem and nonideal Navier-Stokes equations. These equations involve the pair radial distribution function (similar to the two-point correlation function used to characterize the large-scale structures of the Universe), similarly to the interaction energy and equation of state in liquids. Within this framework, small-scale correlations lead to a nonideal amplification of the gravitational interaction energy, whose omission leads to a missing mass problem, for instance, in galaxies and galaxy clusters. Methods. We propose to use a decomposition of the gravitational potential into a near- and far-field component in order to account for the gravitational force and correlations in the thermodynamics properties of the fluid. Based on the nonideal virial theorem, we also propose an extension of the Friedmann equations in the nonideal regime and use numerical simulations to constrain the contribution of these correlations to the expansion and acceleration of the Universe. Results. We estimate that the nonideal amplification factor of the gravitational interaction energy of the baryons lies between 5 and 20, potentially explaining the observed value of the Hubble parameter (since the uncorrelated energy accounts for ∼5%). Within this framework, the acceleration of the expansion emerges naturally because the number of substructures induced by gravitational collapse increases, which in turn increases their contribution to the total gravitational energy. A simple estimate predicts a nonideal deceleration parameter qni ≃ −1; this is potentially the first determination of the observed value based on an intuitively physical argument. We also suggest that small-scale gravitational interactions in bound structures (spiral arms or local clustering) could yield a transition to a viscous regime that can lead to flat rotation curves. This transition could also explain the dichotomy between (Keplerian) low surface brightness elliptical galaxy and (nonkeplerian) spiral galaxy rotation profiles. Overall, our results demonstrate that nonideal effects induced by inhomogeneities must be taken into account, potentially with our formalism, in order to properly determine the gravitational dynamics of galaxies and the large-scale Universe.

A self-similar solution for shock waves in conducting rotating non-ideal dusty gas medium with monochromatic radiation and magnetic field

Abstract In this paper, the cylindrical shock wave propagation in a perfectly conducting rotating mixture of micro size dust particles and van der Waal gas with magnetic field either axial or azimuthal and monochromatic radiation is investigated. The effect of thermal radiation is included in the energy equation of the governing system. In our study, it is assumed that the flux of radiation moves in the mixture of particles and real gas with invariable intensity and the shock wave is moving appositive to the direction of radiation heat flux and the energy is engrossed behind the cylindrical shock only. In the present model, dusty gas is assumed to be a mixture of micro size dust particles and van der Waal gas in which solid particles are continuously distributed and the equilibrium flow conditions are assumed to hold in the entire flow-field region. The effects of the particles’ density to the initial gas density ratio, the real gas effect, rotational parameter, the concentration of mass of the micro size dust particles in the conducting mixture, Alfven-Mach number and the adiabatic exponent on shock and on the physical variables such as velocity, density etc. are discussed. It is found that due to the rotating medium consideration or by an increase in small particles density to the initial gas density ratio, the shock wave strength increases. Also, it is significant to memorize that the strength of the shock wave decreases by an increase in the strength of initial magnetic field or gas non-ideal parameter or the adiabatic index.

Shock wave propagation in a non-ideal rotating medium with azimuthal magnetic field effect using Lie group technique

The present article demonstrates the propagation of a strong cylindrical shock wave in a rotating adiabatic flow of a van der Waals gas in the presence of an azimuthal magnetic field. Using the Lie group technique, self-similar solutions are obtained with an assumption of uniform density in the undisturbed medium. In contrast, the azimuthal component of the fluid velocity and the magnetic field are supposed to vary. The profiles of the flow variables are depicted graphically, followed by a brief discussion on the behavior of the solutions obtained through the graph. The effects of variation in the values of the adiabatic index, Alfvén Mach Number, non-idealness parameter, and the ambient azimuthal velocity exponent on the flow variables are discussed in detail. The computational work is performed by using Mathematica (a software package).

Simplified Digitizing Interface-Architectures for Three-Wire Connected Resistive Sensors: Design and Comprehensive Evaluation

This article describes the design, analysis, and performance verification of simple digitizing interfaces for different types of three-wire resistive sensors. The proposed interface uses an efficient resistance-to-time conversion technique that charges an internal capacitor, between two reference levels, through selected resistive-sensor paths. A simple analog circuit controlled using a digital timing unit realizes the aforementioned technique. This approach is adaptable for various resistive sensor configurations and does not depend on the effect of connecting wire resistances and various other non-ideal parameters (e.g., threshold voltage and pin resistance of microcontroller, offset voltage of comparator, etc.). In addition, the proposed schemes utilize its digital unit (e.g., microcontroller) only for control and timing operations, thus saving on power. The detailed working principle of the proposed interfaces and their error analysis are discussed in the article. Later, performance verification is carried out using simulation as well as emulation studies. These studies clearly show that the presented digitizing interfaces provide linear digital transfer characteristics with maximum nonlinearity of 0.17% and wire resistance compensation. Further, tests are conducted with various remotely located commercial sensors. The outcomes of these studies are reported and compared with the state-of-the-art works.

Solution of One-dimensional weak shock wave problem in a Non-ideal dusty Medium: An analytical approach

The main emphasis of the present study is to construct an analytical solution subjected to weak shock-jump conditions (R-H conditions) for the propagation of a one-dimensional adiabatic flow of non-planar weak shock waves in a two-phase gas-particle medium (mixture of non-ideal gas and small solid spherical dusty particles). By taking into account the methodology used by Murata, the influence of mass concentration of solid particles and van der Walls parameter of non-idealness has been reported explicitly on the exact solution of flow parameters and total energy of the flow field behind the shock front. Also, an investigation has made for the estimation of radius of shock front and results has been illustrated via figures. It has been observed the radius of shock front (damage radius) attenuates faster with time on increasing the impact of mass concentration of solid particles and volumetric parameter in the mixture.

Flow behind an exponential shock wave in a perfectly conducting mixture of micro size small solid particles and non-ideal gas with azimuthal magnetic field

Unsteady adiabatic and isothermal flows behind an exponential spherical or cylindrical shock wave in a perfectly conducting mixture of micro size small solid particles and non-ideal gas under the influence of azimuthal magnetic field is investigated. The moving piston drives the shock wave. The azimuthal magnetic field in the ambient medium is assumed to be varying according to exponential laws. In our study, micro size solid particles are taken to be pseudo-fluid with the supposition that the equilibrium conditions for flow are maintained in the entire flow- field region, and the heat conduction and the viscous-stress of the conducting mixture are negligible. In both the isothermal and adiabatic cases, similarity solutions are obtained by taking into consideration the magnetic field and compressibility. The effects on the shock wave propagation and on the flow variables by the ratio of the density of micro size solid particles to the initial density of the gas Ga as well as by the non-idealness parameter δ of the gas in the conducting mixture, by the mass concentration λp of micro size solid particles in the conducting mixture and by the adiabatic exponent γ are worked out in detail. A relationship between the solutions in the cases of isothermal and adiabatic flows is made. It is found that due to the thought of zero temperature gradient the flow variables fluid velocity, density and magnetic field and shock strength decrease. Also, it is important to note down that the shock wave strength enhances with an increase in Gaor due to change in geometry from cylindrical to spherical; whereas it decreases with an increase in the non-idealness parameterδ or the strength of ambient magnetic field MA−2or the adiabatic exponent γ .

Effect of Laser Radiation on the Dynamics of Active Brownian Macroparticles in an Extended Plasma-Dust Monolayer.

Using the modified method of Brownian dynamics, the dynamics of macroparticles with a uniform metal coating in a plasma-dust monolayer under the action of laser radiation was simulated. The time dependences of the root-mean-square and average linear displacements of particles were calculated for different initial effective parameters of nonideality and different intensities of laser radiation. A relationship was established that connects the effective parameter of nonideality of the dusty plasma system of active particles with the maximum value of the mean linear displacement of particles.

Large Tunable 16-Tupled Millimeter Wave Generation Utilizing Optical Carrier Suppression With a Tunable Sideband Suppression Ratio

Coping up with the rising bandwidth demands for 5G ultra-high speed applications, utilizing millimeter (MM) wave spectrum for data transmission over the radio over a fiber-based system is the ideal approach. In this study, a highly conversant and spectrally pure photonic generation of a 16-tupled MM wave signal using a series-connected DD-MZM with a lower modulation index, a splitting ratio, and a wider tunable range is presented. A 160-GHz MM wave is generated through a double sideband optical carrier suppression technique having an optical sideband suppression ratio (OSSR) of 69 dB and a radio frequency sideband suppression ratio (RSSR) of 40 dB. However, the OSSR and the RSSR are tunable with values greater than 15 dB when the modulation index (M.I.) varies from 2.778 to 2.873, ±8° phase drift, and a 15-dB enhancement in the OSSR with a wider nonideal parameter variation range giving acceptable performance can be seen in the model as compared with previous research works.