Voltage Graphs Research Articles

Solar technology for the production of Bi/Pb superconducting ceramics and its properties

Based on the experience of isostoichiometric and isostructural oxides production using solar energy, the prospects for synthesizing of Bi/Pb superconducting ceramics are shown. The principle of technology in the Large Solar Furnace (Parkent), the influence of gradient conditions on the formation of the oriented structure of crystallites-nuclei, and the connection of the innate properties of precursors with the lamellar morphology and phase composition of massive ceramics are described. The homophase composition of Bi/Pb ceramics was determined. Graphs of resistance and voltage of BSCCO in the temperature range 80-320K are presented. Anomalous of resistance and magnetic susceptibility in bismuth cuprates synthesized by solar energy were observed. Experimental graphs in resistance and magnetic susceptibility changes represent dependencies characteristic of the potential superconducting transitions. The manifestation of the Meissner effect at room temperature and normal atmospheric pressure and daylight, and under the influence of light is shown. The properties of Bi/Pb ceramics are explained by the connection with the innate properties of precursors obtained by concentrated solar energy.

Structural and Spectral Properties of Chordal Ring, Multi-Ring, and Mixed Graphs

The chordal ring (CR) graphs are a well-known family of graphs used to model some interconnection networks for computer systems in which all nodes are in a cycle. Generalizing the CR graphs, in this paper, we introduce the families of chordal multi-ring (CMR), chordal ring mixed (CRM), and chordal multi-ring mixed (CMRM) graphs. In the case of mixed graphs, we can have edges (without direction) and arcs (with direction). The chordal ring and chordal ring mixed graphs are bipartite and 3-regular. They consist of a number r (for r≥1) of (undirected or directed) cycles with some edges (the chords) joining them. In particular, for CMR, when r=1, that is, with only one undirected cycle, we obtain the known families of chordal ring graphs. Here, we used plane tessellations to represent our chordal multi-ring graphs. This allowed us to obtain their maximum number of vertices for every given diameter. Additionally, we computationally obtained their minimum diameter for any value of the number of vertices. Moreover, when seen as a lift graph (also called voltage graph) of a base graph on Abelian groups, we obtained closed formulas for the spectrum, that is, the eigenvalue multi-set of its adjacency matrix.

Epileptiform Discharges Recorded as Monopoles and Dipoles in the EEG: A Practical Approach to Differentiate Tangential and Radial Generators Using Electrode Position Versus Voltage Graphs.

Differentiating dipoles (tangential generators) from monopoles (radial generators) in routine EEG reading can be difficult. The polarity of sharp waves seen on surface EEG will change depending on the generator being located at the wall of the sulcus versus the crown of a gyrus. In this article, the authors introduce visual rules that may be used to determine polarity and estimate the localization of potentials during analysis of the EEG. They also review a practical approach to differentiate monopoles (radial generators) from dipoles (tangential dipoles) in the surface EEG using "electrode position versus voltage graphs." Finally, the authors illustrate examples of dipoles and monopoles with focal spikes located in the following locations: (1) bipolar spikes located in the anterior bank of the central sulcus, (2) bipolar spikes located in the posterior bank of the central sulcus, (3) monopolar spikes located in the crown of the precentral gyrus, (4) bipolar spikes with a vertically oriented dipole originated within the temporal (inferior) bank of the Sylvian fissure, and (5) monopolar spikes located in the convexity of a temporal gyrus. In summary, this article discusses electrographic features of spikes localized in various fissures and gyri and provides practical rules that permit the identification and location of dipoles and monopoles in standard scalp EEG recordings.

Investigation of the influence of the number of poles on the external characteristic of a brushless DC machine in the generator mode

The article presents the results of a study on the generator mode of operation of a brushless DC machine (BLDC) when operating under active load. For analysis, two models were created with the number of permanent magnets on the rotor differing by a factor of two. The relevance of the research is due to the wide range of applications of BLDC in various fields. One of the key advantages of BLDC is the absence of a brush-commutator unit, which is replaced by a controller with semiconductor elements. This increases the reliability of BLDC and expands the range of operating modes. The main objective of this study is to determine the impact of the number of permanent magnets on the external characteristic of BLDC in generator mode. To achieve this goal, computer modeling was performed using ANSYS Maxwell software. This software is designed to study and calculate the magnetic field pattern using the finite element method in electromechanical devices, providing accurate results for analysis. For each BLDC model, the degree of saturation of the magnetic system elements was determined, and graphs of voltage, current, and braking torque at the generator shaft over time were obtained. Analysis of the calculation results for BLDC models with 46 and 92 permanent magnets demonstrated an impact on the voltage and current waveforms, leading to some slight distortion of their shape. The obtained calculation results allowed determining the efficiency and constructing the external characteristic for both BLDC models. Higher efficiency was obtained for the BLDC model with 92 permanent magnets on the rotor. The external characteristic for the generator mode of BLDC operation demonstrated a change in voltage when transitioning from idle to nominal current operation within the range of 15% and 21%, indicating the stiffness of the characteristic. The conclusions of the study indicate the potential for improving the efficiency of BLDC through optimization of the magnetic system design and cooling conditions, and can be useful for engineers and developers of electromechanical systems aiming to improve the performance of their products.

Simulation of voltage characteristics of vapor-gas shell during electrolyte-plasma treatment

Electrolytic plasma processing (EPT) is a method of surface treatment of materials based on the use of plasma and an electrolytic solution. This abstract discusses the principle of action, main applications and potential benefits of EPТ. The EPТ technique involves immersing the object being treated in an electrolytic solution, after which an electric current is applied, causing decomposition of the solution and the formation of a plasma cloud at the surface of the material being processed. Exposure to plasma and chemically active components of the solution makes it possible to modify the surface of the material, improving its properties, such as adhesion, strength and corrosion resistance. EPТ is widely used in a variety of industries, including metalworking, electronics, medical equipment and food processing. The advantages of the method include high efficiency, the ability to process complex shapes and materials, as well as environmental safety due to the absence of the use of chemically aggressive substances. Electrolytic plasma processing is a promising direction in the field of surface modification of materials with a wide range of potential applications. In this paper, theoretical studies of vapor-gas shell formation in the near-surface region of structural steels in the cathodic heating mode of electrolyte-plasma treatment were considered. The technology of electrolyte-plasma hardening, providing the required mechanical properties of products, which are often subjected to wear, temperature and force effects, was investigated. Based on the results of theoretical studies, mathematical calculations of voltage, current density, and dependence graphs were made to obtain a model of vapor-gas shell formation in the process of cathodic heating. Modeling of calculations of vapor-gas shell formation in the process of cathodic heating was carried out with the help of Maple program.

Realizations of crystal nets. I. (Generalized) derived graphs.

A crystal net can be derived from a `generalized' voltage graph representing a graph analog of a fundamental domain of that crystal net along with a sufficient collection of its symmetries. The voltage assignments include not only isometries to the (oriented) edges, but also `weight' groups assigned to vertices for generating the vertex figures around those vertices. By varying the voltage assignments, one obtains geometrically distinct - and occasionally topologically distinct - Euclidean graphs. The focus here is on deriving simple graphs, i.e. graphs with no loops or lunes, especially uninodal edge transitive graphs.

Evaluation of synthesized new cellulose derivatives to make diodes and investigation of electrical and photoelectrical characteristics of these diodes

Firstly, two new cellulose derivatives (CelB33′44′TD and Cel44′OA) were synthesized, which were confirmed by FTIR and 13C CP-MAS NMR spectra. These derivatives were then used in the construction of new diodes (Au/CelB33′44′TD/p-Si and Au/Cel44′OA/p-Si). Later, the atomic force microscope (AFM) images of the interface layers were taken, and the current–voltage (I–V) graphs of the diodes were determined both in the dark and under different illumination intensities (DIIs). Using the Bethe's thermionic emission (TE) theory the ideality factors and barrier heights of the diodes, using the Cheung & Cheung functions the ideality factors, series resistances and barrier heights of the diodes, and using the Norde function the barrier heights and series resistances of the diodes were calculated. Finally, the capacitance–voltage (C–V) and conductance–voltage (G–V) graphs of the diodes at different frequencies (DFs) were examined and some frequency-dependent electrical parameters of the diodes were calculated using the 1/C2–V plots.

Development low-cost processor for photovoltaic simulator

The power generated by a PV array is affected by several factors such as the intensity of solar radiation, the temperature, and the shade cast by solar radiation on the solar panels’ surface. In order to provide the maximum electrical power, it is important to understand the characteristics of a PV system. In this paper, a simulator to observe the characteristics of solar panels is modeled and designed by utilizing tungsten-halogen lamps as a lighting source. The use of halogen lamps ensures that the solar panels’ output signal does not have a large ripple. It differs from other lamps, such as LEDs, which can generate greater ripples in solar panel output signals. Voltage sensors and current sensors are used to obtain the desired values of voltage and current parameters. The characteristics of solar panels with different combinations of lighting can be observed using a Personal Computer (PC) both in the form of tables and graphics with the help of the Parallax Data Acquisition tool (PLX-DAQ). According to the results of the test, the simulator can operate properly, and the measured parameter value can be monitored in realtime in the form of current and voltage graphs.

Impact of Parametric Variation on the Characteristics and Performance of CNTFET Inverter

In this paper, a simple carbon nanotube field effect transistor (CNTFET)-based inverter has been simulated and the impacts of changing various design and process parameters on its characteristics and performance have been analysed using HSPICE. The 32 nm CNTFET model of Stanford University has been used here for the simulation of the inverter. The simulation results and the voltage transfer characteristics (VTC) curve of the inverter have been extracted for (i) different channel lengths, (ii) top gate di-electric material thickness (tox), (iii) pitch value (iv) the number of tubes in CNTFET channel region and (v) chirality of the CNT. It has been observed that the VTC curve changes significantly with different values of these parameters. Some important output parameters like maximum dc current, power, rise time, fall time, average propagation delay, etc. have been measured in each case. Changes in maximum power consumption value due to the change in different parameter values are observed through plotted graphs. Output dc current vs. input voltage graphs have been plotted for different chirality of the tubes, the number of the tubes, and pitch values between n-type CNTFET and p-type CNTFET of the inverter.

Predicting the miniaturization limit of vertical organic field effect transistor (VOFET) with perforated graphene as a source electrode

Vertical organic field effect transistors (VOFETs) are of paramount importance due to their fast switching speed, low power consumption, and higher density on a chip compared to lateral OFETs. The low charge carrier mobility in organic semiconductors and longer channel lengths in lateral OFETs lead to higher operating voltages. The channel length in VOFETs can be less than 100 nm which reduces the size of the channel and hence the operating voltages. Another important factor in the operation of VOFETs is the thickness and width of the source electrode. The channel length, source electrode thickness and width sets the miniaturization limit of the VOFETs. The graphene monolayer can be exploited as a source electrode due to its thinness, high carrier mobility, and metallic behaviors. However, for better gate modulation, perforations in the source material are desired. Here, we simulate the VOFET having perforated graphene monolayer as a source electrode and n-type organic semiconductor N, N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) as an active channel material, while aluminum as a drain electrode to predict the best-miniaturized device. The miniaturization limit of such a VOFET has a limit to the gate opening/perforation in which the minimum source width is 10 nm, as in the sub 10 nm range graphene starts behaving like a semiconductor. The subthreshold swing, deduced from the drain current (J D) versus gate voltage (V G) graph, advocates the limit of the organic semiconductor height/channel length to 50 nm, while 50 nm for the gate.

A Soft Computing Intelligent Control Algorithm to Extract Maximum Energy from Solar Panel

Utilizing soft computing, a maximum power point tracking (maximum PPT) control algorithm is developed, and its performance is compared to that of more traditional Lead Acid battery charging methods such as incremental conductance technique-based maximum PPT. Since the power vs voltage graph of a photovoltaic (PV) cell is nonlinear, a suitable control method seeks to obtain the highest power under dynamic conditions. In order to construct a PV cell with the maximum PPT, a fuzzy logic control approach known as soft computing is used. The cell active energy is used to charge the lead acid battery. A fuzzy logic compares its performance with the incremental conductance technique under dynamic conditions. Moreover, dc to dc converter is required to maintain constant output voltage to charge the battery under low level voltage. A zeta converter is taken to maintain output voltage under various insolation. The significance of algorithm is demonstrated by MATLAB Simulation results and hardware results.

Kit of Uniformly Deployed Sets for p-Location Problems

This paper deals with p-location problem solving processes based on a decomposition, which separates the creation of a uniformly deployed set of p-location problems from the solution of the p-location problem for that specific instance. The research presented in this paper is focused on methods of construction of uniformly deployed sets of solutions and the examination of their impact on the efficiency of subsequent optimization algorithms. The approaches to the construction are used for the constitution of predetermined families of uniformly deployed sets of p-location problem solutions, which have standard sizes. We introduce two methods of uniformly deployed set construction: the first one is based on composition, followed by an enlargement process; and the second one makes use of voltage graphs. The construction approaches are completed by an algorithm, which adjusts the set of solutions to the sizes of a solved instance. The influence of a set construction approach on solving process efficiency is studied on real-world benchmarks, which include both the p-median objective function and the generalized disutility function. The solving process is performed alternatively using the swap or path-relinking based methods. Results of the computational study obtained by all combinations of the mentioned approaches are presented and evaluated in the concluding part of the paper to make the studied characteristics visible.

Voltage Lifts of Graphs from a Category Theory Viewpoint

ABSTRACT We prove that the notion of a voltage graph lift comes from an adjunction between the category of voltage graphs and the category of group labeled graphs.

Effect of welding speed and wire feed rate on arc characteristics, weld bead and microstructure in standard and pulsed gas metal arc welding

Standard and pulsed gas metal arc welding (GMAW) were performed at a constant welding speed of 300, 600, and 1000 mm/min with eight different wire feed rates (WFR). The effect of input parameters on arc stability, metal transfer mode, penetration depth, hardness, and microstructure was discussed. Voltage and current transients recorded by oscilloscope were used to analyse the arc stability and metal transfer mode by plotting probability density distribution (PDD) graphs of arc voltage and welding current. With an increase in WFR, standard GMAW transformed from bimodal to unimodal (due to the absence of short-circuiting mode and activation of pulsed mode) and the pulsed GMAW graph transformed from multimodal to bimodal (due to faster droplet detachment and lowered background current duration). In addition, a nonlinear mathematical model was generated to adequately predict bead profile parameters. For both standard and pulsed GMAW, maximum penetration depth was achieved at the lowest welding speed and highest WFR. But deeper penetration was achieved in pulsed G compared to the standard for the same input parameters. Hardness and the number of non-diffusional phases in the weld and heat-affected zone (HAZ) increased with welding speed.

ГРАФОАНАЛИТИЧЕСКОЕ ИССЛЕДОВАНИЕ РЕЖИМОВ ОДНОФАЗНОГО ЗАМЫКАНИЯ НА ЗЕМЛЮ

Relevance To determine the damaged phase in single-phase earth faults (SPEF), as well as for the purposes of relay protection and signaling of earth faults, it is important to know the phase voltages and the zero sequence voltage. Phase voltages are used to determine the damaged phase and determine the location of the damage. The zero sequence voltage is used to perform nonselective signaling of the SPEF and to determine the completeness coefficient of the fault in adaptive earth fault protections in networks with low earth fault currents. Single-phase short circuits in 6–35 kV networks occur as a rule through a fault resistance, the value of which can reach 5–7 kOhm or more. The fault resistance at the point of damage changes the values of both the zero sequence current and all phase voltages, and the zero sequence voltage. Therefore, the study of single-phase earth fault modes and the assessment of the effect of fault resistance on phase voltages and voltage. Aim of research The main aim of the research is to develop graphoanalytic methods for studying modes for SPEF through fault resistance in networks with an isolated neutral. Research methods Graphoanalytic methods are used to study the effect of fault resistance on phase voltages. The construction of phase voltage graphs directly in the fault resistance function may performe only for a specific electrical network. In the article, to perform the analysis in a generalized form, the equations of phase voltages are used as a function of intermediate variables, which depend on the value of the fault resistance, but do not depend on the parameters of the electrical network. As intermediate variables, the damage completeness coefficient, the relative fault resistance, as well as the angle by which the vector of zero sequence voltage, taken with the reverse sign, lags behind the vector of the pre-emergency voltage of the damaged phase. The main advantage of the phase voltage equations in the function of intermediate variables is that such equations have the same form for any electrical network. At the same time, voltage graphs and superimposed graphs of other parameters of the SPEF mode in relative units can be used as nomograms and allow us to study SPEF modes in a wide range of changes in fault resistances. Results Equations are obtained for the relative values of phase voltages and zero sequence voltages as a function of the damage completeness coefficient and the relative values of the fault resistance. Graphs of phase voltages and zero sequence voltages are constructed. Graphs of changes in the damage completeness coefficient and relative fault resistance are combined with voltage graphs. The obtained equations and constructed graphs are universal in nature, valid for any electrical network with an isolated neutral and can be used as nomograms for determining and analyzing all parameters of the SPEF mode in relative units. Formulas and examples of transition to named units are given.

Voltage graphs as a technique to obtaining semi-cubic cages (Brief Announcement)

In this work, I use some specific voltage graphs to study a generalization of the Cage Problem. In particular, we construct families of semi-cubic graphs with fixed girth and few vertices. Some of them are the smallest that exist because they attain the previously lower bounds.

ИССЛЕДОВАНИЕ ПОВЫШАЮЩЕГО ПРЕОБРАЗОВАТЕЛЯ ПОСТОЯННОГО НАПРЯЖЕНИЯ НА БАЗЕ МНОГОФУНКЦИОНАЛЬНОГО ИНТЕГРИРОВАННОГО ЭЛЕКТРОМАГНИТНОГО КОМПОНЕНТА

The relevance The methods of functional integration of discrete electrical and electromagnetic components allow increasing the reliability and efficiency of electrical energy conversion systems, reducing their weight and dimensions. The authors proposed a circuit solution based on the replacement of some individual discrete components of a DC boost converter with a multifunctional integrated electromagnetic component (MIEС). The component performs the functions of an inductor and a filter capacitor. Aim of research This article discusses the investigation of a DC voltage booster converter based on a multifunctional integrated electromagnetic component. The main task is to investigate a DC voltage booster converter based on a multifunctional integrated electromagnetic component. Research methods In this study, the following methods were used: the study of scientific literature and computer simulation in the Matlab environment. Results A computer model of a step-up DC voltage converter based on MIEС in the Circuit Simulator software package has been developed. Graphs of the output voltage are obtained. The circuits of step-up DC voltage converters are analyzed. A circuit of a DC voltage boost converter based on MIEС has been assembled. Output voltage waveforms were taken. An analysis of the computer model and laboratory test sample was carried out. A set of works has been completed to improve the output characteristics of a step-up converter based on MIEС. The optimal scheme has been chosen to implement the replacement of the inductor and filter capacitor with a multifunctional integrated electromagnetic component. Conducted laboratory studies confirmed the operability of MIEС as a replacement for individual discrete components of the DC voltage boost converter circuit. The optimal mode of operation of the boost converter based on MIEС is determined, which makes it possible to expand the output voltage range and reduce ripples. Expansion of the output voltage range is feasible due to the near-resonant or resonant mode of operation of the converter, which is feasible due to the MIEС structure, which is a resonant LC circuit.

Iwasawa Theory of Jacobians of Graphs

The Jacobian group (also known as the critical group or sandpile group) is an important invariant of a finite, connected graph $X$; it is a finite abelian group whose cardinality is equal to the number of spanning trees of $X$ (Kirchhoff's Matrix Tree Theorem). A specific type of covering graph, called a derived graph, that is constructed from a voltage graph with voltage group $G$ is the object of interest in this paper. Towers of derived graphs are studied by using aspects of classical Iwasawa Theory (from number theory). Formulas for the orders of the Sylow $p$-subgroups of Jacobians in an infinite voltage $p$-tower, for any prime $p$, are obtained in terms of classical $\mu$ and $\lambda$ invariants by using the decomposition of a finitely generated module over the Iwasawa Algebra.

Possibilities to reduce the impact of vfd on the quality of electric power in the networks of enterprises and the cost of its use

Purpose. Simulation modeling of internal power supply systems and comparative assessment on its basis of the total distortion coefficients of the sinusoidal voltage curve. Methodology. Methods of simulating modeling of internal power supply systems. Numerous methods for processing the obtained results. Methods for calculating the discrete Fourier transform. Findings. To increase the level of automation of technological processes in industrial electrical installations, frequency converters are widely used. Together with all the advantages of using a variable frequency drive, it leads to a distortion of the sinusoidal shape of the voltage graph. The article evaluates the total distortion factor of the sinusoidal voltage curve for two options for constructing an internal network of an industrial enterprise. The proposed solution makes it possible to improve the shape of the voltage curve by reducing the number of non-linear semiconductor elements in the power supply system and reduce the influence of higher harmonic components on the power grid. At the same time, this makes it possible to reduce the cost of using VFD at the enterprise. Originality. Through experimental research, it has been established that the use of a common rectifier in combination with a common DC bus and individual inverters can reduce the total distortion coefficient of the sinusoidal voltage curve. Practical value. The developed simulation models of the workshop network’s operation make it possible to study the indicators of the electric energy quality both in stationary and in transient modes of operation.

An alternative approach to extract diode parameters from metal–semiconductor–metal asymmetric Schottky diodes

Back-to-back connected asymmetric Schottky diodes having metal–semiconductor–metal (MSM) configuration are often encountered practically in solid state devices and, if the intended ohmic contact exhibits rectifying characteristics, then the extraction of diode parameters such as ideality factor and barrier height from forward current–voltage (I–V) plots using conventional methods becomes problematic. In this study, a new approach, which predicts extremums in measured current–voltage (I–V) graph assuming the dominant transport mechanism to be thermionic emission model, have been proposed. Using the proposed method, the first and second derivatives of the voltage- current function in combination to another previously established theoretical approach resulted in significantly accurate extraction of individual barrier heights of a MSM junction from single experimental I–V measurement. On the other hand, if individual barrier heights are known, using the proposed method the individual ideality factors for the two back-to-back junctions can be calculated. The proposed method has been validated by analyzing experimentally fabricated FeGa/n-Si/Ag and Co/n-Si/Ni MSM Schottky diodes. The obtained results from this approach have been compared with other established methods and the values were found out to be in good agreement with each other.