Electrical Variable Research Articles

Interpretation of Building Maintenance Factors on Employee Convenience at The Factory of PT Campina Ice Cream Industry Tbk

Buildings are an essential part of human life. Building maintenance is carried out to provide security and comfort for building users. This study aims to determine and analyze the implementation of building maintenance, the influence of maintenance factors on building maintenance, and what maintenance factors have a dominant influence on the comfort of building users at PT. Campina Ice Cream Industry Tbk. This study uses a quantitative approach to data collection using a questionnaire. The population used in this study were employees at the PT. Campina Ice Cream Industry Tbk has a total of 520 employees. Meanwhile, the research sample was 72 employees at PT. Campina Ice Cream Industry Tbk. The data was tested using the validity test and reliability test. The analytical method used is multiple linear regression analysis with hypothesis testing using the t-test. The study results show that the condition of building maintenance is carried out at the factory of PT. Campina Ice Cream Industry Tbk, through architectural, mechanical, and electrical maintenance, has been carried out well, starting from wall and window maintenance and wall/glass cleaning, properly providing and maintaining health facilities, and holding office facilities and infrastructure, especially in regular electrical installations. The results of the t-test show that architectural, mechanical, and electrical maintenance has a significant effect on comfort. The building maintenance variable that has the dominant influence on comfort is the electrical maintenance variable.

An electromechanically coupled beam model for dielectric elastomer actuators

In this work, the Cosserat formulation of geometrically exact beam dynamics is extended by adding the electric potential as an additional degree of freedom to account for the electromechanical coupling in the dielectric elastomer actuators. To be able to generate complex beam deformations via dielectric actuator, a linear distribution of electric potential on the beam cross section is proposed. Based on this electric potential, the electric field and the strain-like electrical variable are defined for the beam, where the strain-like electrical variable is work-conjugated to the electric displacement. The electromechanically coupled strain energy for the beam is derived consistently from continuum electromechanics, which leads to the direct application of the material models in the continuum to the beam model. The electromechanically coupled problem in beam dynamics is first spatially semidiscretized by 1D finite elements and then solved via variational time integration. By applying different electrical boundary conditions, different deformations of the beam are obtained in the numerical examples, including contraction, shear, bending and torsion. The damping effect induced by the viscosity as well as the total energy of the beam are evaluated. The deformations of the electromechanically coupled beam model are compared with the results of the 3D finite element model, where a good agreement of the deformations in the beam model and that in the 3D finite element model is observed. However, less degrees of freedom are required to resolve the complex deformations in the beam model.

Review on Dynamic Simulation of Wind Diesel Isolated Microgrids

Wind diesel isolated microgrids (WDIMs) combine wind turbine generators (WTGs) with diesel generators (DGs) to supply electricity to remote consumers. WDIMs are low-inertia isolated power systems where large system frequency and voltage variations occur. WDIM dynamic modeling allows short-term simulations to be performed and detailed electrical variable transients to be obtained so that the WDIM power quality and stability can be tested. This paper presents a literature review about WDIM dynamic simulation. The review classifies articles according to factors such as the different WDIM operation modes (diesel only, wind–diesel and wind only) simulated, the types of WTGs used in the WDIM (constant- and variable-speed types), or the use of different short-term energy storage technologies (batteries, ultracapacitors, flywheels) to improve the WDIM power quality, stability and reliability. Papers about the dynamic simulation of related isolated microgrids are also reviewed. Finally, as an example of WDIM dynamic simulation, a WDIM with one WTG, one DG, load and a discrete dump load (DL) is modeled and simulated. The WDIM response to variations of wind speed and load consumption is shown by graphs of the main electrical variables. The simulations show how the DL is used to improve the WDIM stability and reliability.

Pattern selection in coupled neurons under high-low frequency electric field

Biological neurons exposed to an external electric field can induce polarization and charge fluctuation. Indeed, the exchange of calcium, sodium and potassium ions across the cell membrane can induce an electric field as a result of a time-varying electromagnetic field set up. This field could further modulate the cell electrical activity by inducing multiple firing modes. Based on the physical law of electric field, an improved model which includes an additive electrical field variable is constructed for a network of neurons to study wave propagation and mode transition by exploring the longtime dynamics of slightly perturbed plane waves in the network. Wave pattern and mode transition dependence on the different parameters of external electric field are discussed. It is found that the plane wave propagating in the coupled system breaks down to localized structures under the activation of modulational instability. The network under high-low external electric field supports bursting synchronization. This could be a fruitful avenue to discern the occurrence of paroxysmal epilepsy.

Structural and electronic properties of monodomain ultrathin PbTiO3/SrTiO3/PbTiO3/SrRuO3 heterostructures: A first-principles approach

First-principles calculations within the local density approximation were carried out to explain the ground state and electronic properties of a vacuum/PbTiO3/SrTiO3/PbTiO3/SrRuO3 multilayer in a monodomain phase. Open-circuit boundary conditions were assumed, considering the electric displacement field, D, as the fundamental electrical variable. The direction and the magnitude of D can be monitored by proper treatment of the PbO surface layer, introducing external fractional charges Q in the surface atomic layers by means of virtual crystal approximation. Different excess or deficit surface charges (from Q=±0.05 to Q=±0.15) were considered, corresponding to small values of the polarization (up to ±0.16C/m2) in both directions. The layer-by-layer electric polarization, tetragonality, and the profile of the electrostatic potential were computed, as well as the projected density of states, as a function of electric displacement field. The magnitude of D is preserved across the dielectric layers, which translates into a polarization of the SrTiO3 spacer layer. The tetragonality of the two PbTiO3 layers is different, in good agreement with experimental x-ray diffraction techniques, with the layer closer to the free surface exhibiting a smaller value. This is attributed to the interplay with surface effects that tend to contract the material in order to make the remaining bonds stronger. Our calculations show how the final structure in this complex oxide heterostructure comes from a delicate balance between electrical, mechanical, and chemical boundary conditions.

Defining the electromagnetic potentials

This paper offers a critical examination of the classical method of introducing the elecrtromagnetic potentials in a nonrelativistic context. It applies the nonretarded Helmholtz theorem to show that the usual method is ambiguous, with that ambiguity being reflected in the gauge transformation equations. This ambiguity can be removed by carefully invoking the Helmholtz decomposition theorem, but the process exposes the inadequacy of the conventional procedure. It then shows how the retarded Helmholtz theorem can be used to motivate rigorous definitions of the vector and scalar potentials and the field variables based upon the current density as the single electrical source variable. The method depends upon the assumption of causality, hence is restricted to classical field theory. It uses the powerful theory of operators as the main analysis tool.

Study on damage of concrete under uniaxial compression based on electrical resistivity method

This study investigated the relationship between concrete electrical resistivity and compressive damage. The electrical resistivity and damage variable D of concrete under uniaxial compression were measured by the electrode method and ultrasonic method. The mathematical relationship between electrical resistivity and concrete damage variable D was derived. And the mechanism of change of concrete electrical resistivity under stress was explored by Nuclear Magnetic Resonance (NMR). The results showed that the electrical resistivity curve of concrete shows a phased trend of decreasing first and then increasing during loading, which corresponds to the damage evolution of concrete. The derived relationship between electrical resistivity and damage variable D is well correlated with the experimental data. Based on the NMR test results and considering the excess pore water pressure, it was found that the increase in connectivity of pore solution caused by the extruded pore solution filled cement matrix microcrack under stress may be the main reasons for the decrease in electrical resistivity of concrete specimens. Toward failure, the instability and penetration of macrocrack lead to the cutting of concrete matrix, which is the main reason for the increase of electrical resistivity.

Statistical Inference for Visualization of Large Utility Power Distribution Systems

Electrical variable visualization has been widely applied to report the performance and effectiveness of novel devices and strategies in utility power distribution systems. Many graphical alternatives are useful to demonstrate critical characteristics of distribution systems such as voltage regulation or power flow. This visualization of electrical variables can also be an effective approach to analyze, compare and evaluate large-scale systems. However, there is a lack of generalized visualization strategies oriented to perform electrical validations of smart grid strategies in large distribution systems. In this paper, we show that the proposed probabilistic density evolution is a powerful resource for long-term time-sequential simulations. Examinations with an IEEE 8500 node test feeder shows that the proposed approach increases the circuit situational awareness and reduces the validation time. To illustrate this methodology, the dynamic voltage condition was simulated and analyzed to recognize the global effect of voltage regulating equipment. The results show an accurate and convenient support that can be interpreted at first glance. The proper use of long-term field measurements and short time-step simulations is a robust method for future grid research, such as designing an optimum operation of intelligent devices or diagnosing electrical interoperability issues in complex grids.

Efficient transient noise analysis of non‐periodic mixed analogue/digital circuits

This paper proposes a numerical method for accurate time-domain noise simulation of mixed analogue/digital electrical circuits that in principle do not admit a periodic steady-state working condition, such as fractional ΔΣ phase-locked loops (PLLs). By means of a tool known as saltation matrix, which allows dealing with non-smooth vector fields, a variational approach is adopted. The power spectral density of a noisy electrical variable is computed by applying the Thomson's multitaper method (MTM) to the numerical solution of the stochastic variational model of the circuit. This allows to resort to a single transient simulation run, thus avoiding cpu time consuming Monte-Carlo-like approaches. The effectiveness of the proposed method is shown by comparing simulation results related to a commercial fractional ΔΣ PLL with experimental data.

Probabilistic Solution of a Duffing-Type Energy Harvester System Under Gaussian White Noise

This paper proposes a solution procedure to formulate an approximate joint probability density function (PDF) of a Duffing-type energy harvester system under Gaussian white noise. The joint PDF solution of displacement, velocity, and an electrical variable is governed by the Fokker-Planck (FP) equation. First, the FP equation is reduced to a lower-dimensional FP equation only about displacement and velocity by a state-space-split (SSS) method. The stationary joint PDF of displacement and velocity can be solved exactly. Then, the joint PDF of displacement, velocity, and the electrical variable can be approximated by the product of the obtained exact PDF and the conditional Gaussian PDF of the electrical variable. A parametric study is further conducted to show the effectiveness of the proposed solution procedure. The study considers weak nonlinearity, strong nonlinearity, high excitation level, and a bistable oscillator. Comparison with the simulated results shows that the proposed solution procedure is effective in obtaining the joint PDF of the energy harvester system in the examined examples.

Electronic Scheme for Computing Inverse-Cosine and its Application to a GMR Based Angle Sensor

This paper presents a new, simple but effective, electronic method to obtain inverse-cosine of an electrical variable. The proposed method is very useful for linearization of sensors whose output is a cosine or sine function of the physical quantity being sensed. The inverse-cosine of the variable is obtained by comparing it with a reference sinusoidal wave. The proposed method is easy to implement using electronic components. Using the new technique, a giant magneto-resistance-based angle sensor that provides an output linearly proportional to the angle being sensed has been developed, and the details are reported in this paper. A prototype of the angle sensor has been built, and the practicality of the new method has been tested successfully. The developed sensor provides a linear output for a range of 0° to 180°. The worst case error was found to be less than 0.35° for a range of 10°-170°.

On energy transfer phenomena, in a nonlinear ideal and nonideal essential vibrating systems, coupled to a (MR) magneto-rheological damper

In this paper, a control strategy is applied to a nonlinear ideal and nonideal vibrating system coupled to a magneto-rheological damping structure, exhibiting chaotic behavior. In order to suppress the chaotic oscillations and to improve the transient response, a combination of passive (energy pumping) and active (state feedback) control strategies. The chaotic vibrations are suppressed, bringing the system to a desired periodic orbit. Additionally, the control damping force is transformed into the electrical control signal variable.

Finite element analysis of actively controlled smart plate with patched actuators and sensors

The active vibration control of smart plate equipped with patched piezoelectric sensors and actuators is presented in this study. An equivalent single layer third order shear deformation theory is employed to model the kinematics of the plate and to obtain the shear strains. The governing equations of motion are derived using extended Hamilton's principle. Linear variation of electric potential across the piezoelectric layers in thickness direction is considered. The electrical variable is discretized by Lagrange interpolation function considering two-noded line element. Undamped natural frequencies and the corresponding mode shapes are obtained by solving the eigen value problem with and without electromechanical coupling. The finite element model in nodal variables are transformed into modal model and then recast into state space. The dynamic model is reduced for further analysis using Hankel norm for designing the controller. The optimal control technique is used to control the vibration of the plate.

Electromechanical properties of high- coupling (1-ξ)Pb(Zn1/3Nb2/3)O3-(ξ)PbTiO3 single crystals for sound projectors

Isothermal weak field frequency sweeps were conducted over the temperature range 30 to 140 degrees C on multidomain, oriented, and poled (1-x)Pb(Zn(1/3)Nb(2/3))O(3)-xPbTiO(3) (PZN-PT) single crystals with x = 0.045, 0.06, 0.07, and 0.08 near the ferroelectric rhombohedral (FR)-ferroelectric tetragonal (F(T)) morphotropic phase boundary (MPB). The temperature dependencies of the small-signal 33-mode electromechanical properties were derived from the isothermal frequency sweeps. Morphotropic compositions with x = 0.06 and 0.07 PT were found to exhibit the largest electromechanical coupling and piezoelectric coefficient, with k(33) > 0.90 and d(33) approximately 2300 pC/N, and the lowest short-circuit Young's modulus of approximately 9 GPa. Reversible zero-field elastic instability attributable to a F(R)- F(O) transition was observed under isothermal compression-decompression of a 0.94PZN-0.06PT single crystal. The application of a dc bias field enhanced the F(R) stability under compression. The large-signal, dc biased, 33-mode electromechanical response was measured under mechanical compressions similar to those used in sound projectors. The remarkable small-signal electromechanical properties are in a good agreement with the large-signal response. The crystal response to thermal, electrical, and mechanical variable is discussed in terms of high-coupling single crystal models.

First-principles modeling of ferroelectric capacitors via constrained displacement field calculations

First-principles modeling of ferroelectric capacitors presents several technical challenges, due to the coexistence of metallic electrodes, long-range electrostatic forces and short-range interface chemistry. Here we show how these aspects can be efficiently and accurately rationalized by using a finite-field density-functional theory formalism in which the fundamental electrical variable is the displacement field D. By performing calculations on model Pt/BaTiO3/Pt and Au/BaZrO3/Au capacitors we demonstrate how the interface-specific and bulk-specific properties can be identified and rigorously separated. Then, we show how the electrical properties of capacitors of arbitrary thickness and geometry (symmetric or asymmetric) can be readily reconstructed by using such information. Finally, we show how useful observables such as polarization and dielectric, piezoelectric and electrostrictive coefficients are easily evaluated as a byproduct of the above procedure. We apply this methodology to elucidate the relationship between chemical bonding, Schottky barriers and ferroelectric polarization at simple-metal/oxide interfaces. We find that BO2-electrode interfaces behave analogously to a layer of linear dielectric put in series with a bulk-like perovskite film, while a significant non-linear effect occurs at AO-electrode interfaces.

Adsorption of tetraethylammonium ions on Cd(0 0 0 1) single crystal plane from solutions in ethanol

The adsorption of tetraethylammonium (TEA +) ions on the basal (0 0 0 1) plane of the cadmium single crystal from solutions in ethanol has been investigated by impedance measurement method. The experimental data were obtained in 0.02 M mixed-electrolyte solutions and the calculations performed with electrode potential as the independent electrical variable. The Gibbs energy of adsorption of TEA + ions has been calculated using the simple virial adsorption isotherm and it was found that the adsorption of TEA + cations is weaker than the adsorption of halide anions. The electrosorption valency evaluated has a nearly constant value in the potential region studied. It was concluded that the formed effective surface dipole is significantly screened by the solvent molecules and the metal electron gas. Comparing the adsorption characteristics with the parameters obtained for bismuth single crystal electrodes, it was found that the Gibbs adsorption energy on uncharged electrode surface is close for these metals. The results obtained indicate that only weak interaction between TEA + ions and cadmium surface takes place and there is no remarkable partial charge transfer from the adsorbed ions to the Cd(0 0 0 1) surface atoms.

Electric displacement as the fundamental variable in electronic-structure calculations

Finite-field calculations in periodic insulators are technically and conceptually challenging, due to fundamental problems in defining polarization in extended solids. While significant progress has been made recently with the establishment of techniques to fix the electric field E or the macroscopic polarization P in first-principles calculations, both methods lack the ease of use and conceptual clarity of standard zero-field calculations. Here we develop a new formalism in which the electric displacement D, rather than E or P, is the fundamental electrical variable. Fixing D has the intuitive interpretation of imposing open-circuit electrical boundary conditions, which is particularly useful in studying ferroelectric systems. Furthermore, the analogy to open-circuit capacitors suggests an appealing reformulation in terms of free charges and potentials, which dramatically simplifies the treatment of stresses and strains. Using PbTiO3 as an example, we show that our technique allows full control over the electrical variables within the density functional formalism.

Study of adsorption of tetraethylammonium ions on Bi single crystal planes from solutions in ethanol

The adsorption of tetraethylammonium (TEA+) ions on the (001) and \( {\left( {01\overline{1} } \right)} \) planes of the bismuth single crystal from solutions in ethanol has been investigated by impedance measurement method. The experimental data were obtained in 0.02 M mixed-electrolyte solutions and the calculations performed with electrode potential as the independent electrical variable. The Gibbs energy of adsorption of TEA+ ions has been calculated using the simple virial adsorption isotherm, and it was found that the adsorption of TEA+ cations is weaker than the adsorption of halide anions. The electrosorption valency evaluated has a nearly constant value in the potential region studied. It was concluded that the formed effective surface dipole is significantly screened by the solvent molecules and the metal electron gas. The analysis of the impedance spectra was performed by fitting the experimental data to the various equivalent circuits. It was found that the behaviour of TEA+ ions at Bi(hkl)∣ethanol interface can be described with the equivalent circuit, corresponding to the classical Frumkin–Melik-Gaikazyan model. The results obtained indicate that only weak interaction between TEA+ ions and bismuth surface takes place, and there is no remarkable partial charge transfer from the adsorbed ions to the Bi surface atoms.

Adsorption of tetraethylammonium ions on Bi(111) single crystal plane from solutions in ethanol

The adsorption of tetraethylammonium (TEA+) ions on the (1 1 1) plane of the bismuth single crystal from solutions in ethanol has been investigated by impedance measurement method. It was found that the ionic charge due to the specific adsorption of TEA+ ions in ethanol can be obtained using the classical calculation methods for simple ions. The experimental data were obtained in 0.02 M mixed-electrolyte solutions and the calculations performed with electrode potential as the independent electrical variable. The Gibbs energy of adsorption of TEA+ ions has been calculated using the simple virial adsorption isotherm and it was found that the adsorption of TEA+ cations is weaker than the adsorption of halide anions. The electrosorption valency evaluated has a constant value in the potential region studied. It was concluded that the formed effective surface dipole is significantly screened by the solvent molecules and the metal electron gas.

A Vector-Controlled PWM Current-Source-Inverter-Fed Induction Motor Drive With a New Stator Current Control Method

In this paper, the control of the pulsewidth-modulated current-source-inverter-fed induction motor drive is discussed. The vector control system of the induction motor is realized in a rotor-flux-oriented reference frame, where only the measured angular rotor speed and the dc-link current are needed for motor control. A new damping method for stator current oscillations is introduced. The method operates in an open-loop manner and is very suitable for microcontroller implementation, since the calculation power demand is low. Also, the stator current phase error caused by the load filter is compensated without measurement of any electrical variable. With the proposed control methods the motor current sensors can be totally eliminated since the stator current measurements are not needed either for protection in the current-source-inverter-fed drives. The proposed control methods are realized using a single-chip Motorola MC68HC916Y1 microcontroller. The experimental tests show excellent performance in both steady-state and transient conditions.