Distortion Factor Research Articles

Influence of the Polymer Plate Thickness on the Plate Distortion Factor in Flexography

Flexographic printing plate is used for the transfer of image onto a printing substrate. The surface of printing plate is stretched lengthwise when the plate is mounted on plate cylinder. As a result, the print length on the impression is always longer than the actual length of the plate. Prepress must compensate for this difference in length. The result of wrong plate distortion is different print length in flexography compared to the processes that follow printing. The aim of this paper is to research the influence of repeat length in printing and polymer plate thickness on the factor distortion. The distortion factor values were calculated using the derived formulas. Regardless of the repeat length in printing, the value of the thickness factor for a particular printing plate is constant. However, the values of the distortion factor decrease with the increasing thickness of the polymer plate and the decreasing of the total plate cylinder circumference.

Dynamic similitude technique for predicting the behaviour of structures subjected to impact loads

To predict the dynamic behavior of large-scale structures subjected to impact loads by similitude theory is an important design tool for engineers. However, structures under impact loads usually do not follow the usual similarity laws due to material strain-rate effects and geometrical distortion. This paper proposed a dynamic similitude method to predicting the behavior of structures subjected to impact loads where material strain-rate sensitivity and geometrical distortion are both considered. In this work, we firstly deduced a loss function of the dynamic yield stress to obtain the scaling correction factor to remove the strain rate effects by correcting initial impact velocity. Then a distortion factor related to the geometrical distortion was introduced to obtain a new velocity correction factor, which made it possible to reduce the effects of material strain-rate sensitivity and geometrical distortion together. The efficiency of the scaling approach presented in this paper was illustrated by the numerical simulations and experiments of a T-beam model under impact loading and the results showed a small deviation between the predictions of the model and the prototype.

A Modified Forward PFC Converter for LED Lighting Applications

A modified forward power factor correction (PFC) converter for light-emitting-diode (LED) lighting applications is proposed in this paper. The proposed circuit topology is an integration of a forward converter and a flyback converter with a multi-windings transformer. The flyback converter is operated as an auxiliary voltage source (AVS) connected in series with the rectified ac grid voltage to achieve low harmonic current distortion and high power factor. The magnetizing inductance energy is recycled to charge the capacitor in the AVS. The commonly used constant on-time control and primary side regulation can be easily adopted to control the proposed LED driver. The operation principle of the proposed converter is presented followed by the mathematical derivation of the parameter design. An 80 W prototype converter was built and tested to verify the performance of the proposed PFC converter. Experimental results show that the proposed PFC converter can comply with the IEC 61000-3-2 standard with high efficiency, low current harmonics, and a nearly unity power factor under universal input voltage range.

Improved Power Quality Charging System Based on High Step-Down Gain Bridgeless SEPIC APFC for Light Electric Vehicles

The limited voltage gain characteristic of the mainstream dc–dc converter restricts the application in single-stage light electric vehicles’ (LEVs) chargers. Typically, the battery voltage of an LEV is in the range from 24 to 72 V. Thus, while implementing the single-stage LEVs’ chargers, a line- or high-frequency transformer is essentially required. The utilization of transformer, however, compromises the overall cost, size, and efficiency of LEV chargers. Therefore, a transformerless single-stage bridgeless charger topology is presented in this article, aiming to realize a simple, reliable, efficient, and low-cost charger for the LEVs. The presented topology utilizes a switched inductor single ended primary inductance converter (SISEPIC) to achieve a high step-down dc voltage gain. Furthermore, the active power factor correction is incorporated to ensure enhanced power quality (low total harmonics distortion and unity power factor) at the ac supply side during constant current and constant voltage state charging. Additionally, this charger is controlled by employing reduced sensing devices and control complexities. Both simulation and experimental validations are provided to manifest the effectiveness of this SISEPIC charger topology for LEVs.

Dynamic harmonic domain approach to assess performance of three-phase fixed capacitor thyristor controlled reactor (FC-TCR)

Harmonics have become an important issue as the number of non-linear elements and electronic devices coupled to electrical power systems increases by the day. A Fixed Capacitor Thyristor Controlled Reactor (FC-TCR) is widely used in power systems to continuously control reactive power. This paper presents the harmonic analysis of a three-phase FC-TCR under different operating conditions using the Dynamic Harmonic Domain (DHD) technique. The existing Harmonic Domain (HD) method is widely used to obtain the steady-state harmonics in the power grid. It is not possible to calculate transient harmonics using the harmonic domain method. The dynamic harmonic domain technique also provides a solution for the transient condition. The three-phase FC-TCR is simulated in a MATLAB environment and calculates transient harmonic quantities such as apparent power S(t), reactive power Q(t), real power P(t), and distortion power D(t), RMS values, and distortion factors of the three-phase FC-TCR when subjected to voltage disturbance.

Modeling and Simulation of New PWM Techniques for Hybrid 7-Level Inverters Using Simplified Switching Table

Nowadays, Cascade H-bridge (CHB) multi-level inverters (MLI) have many applications in the fields of electric drive control, high-power energy control, medium-voltage power grids, and popularization in the conversion of renewable energy power. In order to improve the quality of MLI to meet today's needs while reducing costs, it is necessary to have new methods to improve the working efficiency of the converter. Therefore, this paper presents a novel PWM control for single-phase cascaded hybrid 7-level inverter using simplified switching table (SST). The SST table converts switching states of the traditional multi-level inverter to the switching state of the hybrid cascaded inverter. The SST table is effectively designed to reduce the number of switching when performing output voltage control, thus improving the converter's working efficiency. The PWM method using proposed SST has the advantage of simple implementation, utilizing the traditional Sin-PWM techniques without re-calculating the control function or changing the carrier waveforms. The effectiveness of the proposed method will be evaluated through the voltage and current harmonic distortion factors when applying level shift carrier arrangements (LS-PWM) and speed control application of 3-phase asynchronous motor. Furthermore, in order to prove the advantage of the PWM technique using the proposed SST, the power loss of the 7-level hybrid cascaded inverter is also calculated and compared with traditional seven-level inverter and 3-level inverter. The analysis and modeling results of the 7-level hybrid inverter control are verified and evaluated using MATLAB SIMILINK and PLECS software.

A NOVEL MULTILEVEL INVERTER’S DESIGN AND IMPLEMENTATION BASED ON PHOTOVOLTAIC SYSTEMS

Inverter and rectifier controllers frequently employ the space vector pulse width modulation (SVPWM) approach. The space vector pulse width modulation is more suitable for digital implementation than sinusoidal pulse width modulation (SPWM) and can enhance the achievable maximum output voltage, with maximum line voltage nearing 70.7 % of the DC link voltage (compared to 61.2 % for SPWM) in the linear modulation range. It can also achieve a lower voltage total harmonic distortion factor. In this work, we apply these two methods to photovoltaic systems based on technical dependence MPPT INC to improve the output voltage of the photovoltaic panel.

Analysis of nonlinear distortions of DpHEMT structures based on the GaAs/InGaAs compound with double-sided delta-doping

Computational and experimental studies of the characteristics of a high-power AlGaAs/InGaAs/GaAs DpHEMT were performed. A self-consistent numerical solution of the Schrodinger and Poisson equations was used to calculate the band diagram and the electron concentration in the channel of the transistor under study. The electron mobility in the transistor channel was estimated experimentally at 9300 cm2/V·s. The obtained transfer current--voltage characteristic of the transistor was used to calculate the parameters of a model differential amplifier (small-signal gain and third-order non-linear distortion factor). Keywords: AlGaAs/InGaAs/GaAs DpHEMT, nonlinear distortion, spacer layers.

JIG AND FIXTURE PENGELASAN SUDUT SIKU UKURAN LEBAR PROFIL (3 - 60 mm) DI JURUSAN TEKNIK MESIN POLITEKNIK NEGERI MALANG

The resulting angle deviation is the result of improper welding methods, in addition, there is also a distortion factor in the workpiece during the SMAW welding process at the workshop in the Department of Mechanical Engineering, State Polytechnic of Malang.The purpose of making this tool is to facilitate and provide time efficiency in the welding process, it is necessary to manufacture jig and fixture tools in the angle welding process. The way the angle welding jig and fixture works is by gripping the workpiece to be welded in a plane that forms an angle so that the object to be welded will follow the angled plane.

Parameterized Complexity of Directed Spanner Problems

We initiate the parameterized complexity study of minimum t-spanner problems on directed graphs. For a positive integer t, a multiplicative t-spanner of a (directed) graph G is a spanning subgraph H such that the distance between any two vertices in H is at most t times the distance between these vertices in G, that is, H keeps the distances in G up to the distortion (or stretch) factor t. An additive t-spanner is defined as a spanning subgraph that keeps the distances up to the additive distortion parameter t, that is, the distances in H and G differ by at most t. The task of Directed Multiplicative Spanner is, given a directed graph G with m arcs and positive integers t and k, decide whether G has a multiplicative t-spanner with at most m-k arcs. Similarly, Directed Additive Spanner asks whether G has an additive t-spanner with at most m-k arcs. We show that (i) Directed Multiplicative Spanner admits a polynomial kernel of size mathcal {O}(k^4t^5) and can be solved in randomized (4t)^kcdot n^{mathcal {O}(1)} time, (ii) the weighted variant of Directed Multiplicative Spanner can be solved in k^{2k}cdot n^{mathcal {O}(1)} time on directed acyclic graphs, (iii) Directed Additive Spanner is {{,mathrm{mathsf{W}},}}[1]-hard when parameterized by k for every fixed tge 1 even when the input graphs are restricted to be directed acyclic graphs. The latter claim contrasts with the recent result of Kobayashi from STACS 2020 that the problem for undirected graphs is {{,mathrm{mathsf{FPT}},}} when parameterized by t and k.

Space Vector-Based Hybrid Pulse Width Modulation for Voltage Source Inverters Using Novel Euclidean Distance Mapping Technique

In this article, a novel Euclidean distance mapping (EDM) technique for space vector pulse width modulated (SVPWM) voltage source inverter (VSI) is presented. The EDM technique processes space vector diagram (SVD) as an image, which simplifies execution of SVPWM. In the proposed technique, Euclidean distance calculation between all eight switching vectors and the tip of the revolving reference voltage vector for every subcycle is carried out. The identification of nearest three voltage vectors (NTV) and switching sequence designs are done on the basis of these Euclidean distances. The EDM-SVPWM technique achieves improvement in the inverter performance in the context of the factors like stator flux ripple over a subcycle, distortion factor (DF), total harmonics distortion (THD) of line voltage, and line current ripple of the inverter. The performance of EDM-SVPWM technique is verified analytically and confirmed experimentally by hardware implementation over the wide range of fundamental frequencies and modulation indices.

Systematic Distortion Factor and Unrecognized Source of Uncertainties in Nuclear Data Measurements and Evaluations

Each experiment provides new information about the value of some physical quantity. However, not only measured values but also the uncertainties assigned to them are an important part of the results. The metrological guides provide recommendations for the presentation of the uncertainties of the measurement results: statistics and systematic components of the uncertainties should be explained, estimated, and presented separately as the results of the measurements. The experimental set-ups, the models of experiments for the derivation of physical values from primary measured quantities, are the product of human activity, making it a rather subjective field. The Systematic Distortion Factor (SDF) may exist in any experiment. It leads to the bias of the measured value from an unknown “true” value. The SDF appears as a real physical effect if it is not removed with additional measurements or analysis. For a set of measured data with the best evaluated true value, their differences beyond their uncertainties can be explained by the presence of Unrecognized Source of Uncertainties (USU) in these data. We can link the presence of USU in the data with the presence of SDF in the results of measurements. The paper demonstrates the existence of SDF in Prompt Fission Neutron Spectra (PFNS) measurements, measurements of fission cross sections, and measurements of Maxwellian spectrum averaged neutron capture cross sections for astrophysical applications. The paper discusses introducing and accounting for the USU in the data evaluation in cases when SDF cannot be eliminated. As an example, the model case of 238U(n,f)/235U(n,f) cross section ratio evaluation is demonstrated.

Influence of Single-Phase Voltage Loss and Load Carrying Mode on Mine Drainage Pump Motor in Vietnam

Mine drainage pump is the most important load in mining which requires high reliabilitywhen operating. Currently, the power supply of a mine drainage pump is connected to the same powerline with many nonlinear loads, and is equipped with power electronic converters, which makes thepower supply nonsinusoidal. During the working process of a mine drainage pump, the load-carryingfactor often changes, and many types of failures occur, among which single-phase voltage loss is themost common problem. In the case of a nonsinusoidal power supply, if a single-phase voltage lossoccurs in different load modes, it will greatly affect the working mode of the mine drainage pumpleading to influences on the working efficiency, the life of the pump, and sometimes it is necessary torecalculate the protection parameters. This paper studies the influence of single-phase voltage loss andload carrying mode on the working mode of mine drainage pump motor in case the of nonsinusoidalpower supply. Research results show that, in the case of nonsinusoidal power supplied with single-phasevoltage loss, copper losses in the rotor and stator circuits increase with increases in voltage totalharmonic distortion (THD) and load-carrying factor, 5th order reverse harmonic increases copper loss inasynchronous motor the most, and higher harmonic components have less effect on copper loss in themotor. At the same time, the speed ripple decreases with the increase of the motor load factor anddecreases in the presence of the 5th order negative sequence harmonic, and increases significantly in thepresence of the 7th order positive sequence harmonic. 5th order negative sequence harmonic increases,the torque ripple increases, while the 7th order positive sequence harmonic reduces the torque ripple inthe case of single-phase voltage loss. The results of the paper will help improve the operationalefficiency of the mine drainage pump in Vietnam's mines.

Design and implementation of a CSI inverter with unipolar SPWM modulation and PR controller for lineal loads

This paper presents a detailed implementation of a current source inverter using unipolar sinusoidal pulse width modulation. This method is uncommon in these types of inverters and the semiconductor devices, integrated circuits, sensors, and filters used in conjunction with the TMS320F28379D microcontroller will be discussed. The inverter was tested in both an open and closed loop with a proportional resonant controller. Satisfactory results in terms of the harmonic distortion factor at the voltage output and the regulation indices for lineal loads were obtained. The response circuit demonstrated its viability for the subsequent connection to an electrical distribution network.

A Comparison of Instantaneous and Extension p-q Methods for Current Controlled Voltage Source Inverter in Microgrid

ABSTRACT With the advancement in technology and population growth, the motivation of integrating utility grid with the microgrid through power electronic converters increases. This paper presents the control of power electronic converter connected at the grid side. This converter regulates the power flow between renewable energy system (RES), load and grid in addition to the compensation of harmonic and reactive power. The reference currents are generated to decide the power flow from RES to the load and to suppress the harmonic and reactive power in the grid making grid current sinusoidal. In this paper, the reference current generation techniques like instantaneous p-q method and extension p-q method are implemented and compared. Linear Quadratic Regulator (LQR) is used to track the reference current. The control law of LQR is designed in a simple way using simplified equivalent circuit of a three-phase grid integrated renewable energy system. The system is tested experimentally under balanced and unbalanced conditions in two different modes such as insufficient renewable power and excess renewable power. The supremacy of extension p-q method over instantaneous p-q method is proved by getting low total harmonic distortion and better power factor under balanced and unbalanced conditions experimentally.

An enhancement approach of Reboost converter for unification of disparate WECS with the utility grid system

The WECS is an important phenomenon to reduce green house gas emission. The power generated from wind energy is clean, zero emission and volatility. The generation of Wind energy is stochastic due to the variation of velocity of wind. The Unification of WECS with the utility grid is a major formidable area of research. The integration of grid with WECS is done by means of Rotor side converter and Grid side inverter. These two converters are linked by using a DC link capacitor in a conventional system. In this paper, a novel topology had been proposed. The conventional system DC link element is replaced by Reboost converter. A Reboost converter is a DC–DC converter which bestows boosting or increased output voltage. It comprises a power MOSFET switch, hence the switching stress is minimized and efficiency of the proposed converter is predominant. The Reboost converter dispenses a continuous input current that lessen the voltage stress. The output ripple voltage and total harmonic distortion factor are minimized. A comparative analysis on different types of wind generators are performed by implementing the Reboost converter. The input voltage total harmonic distortion, output voltage, output power and output voltage total harmonic distortion factor are determined. The MATLAB Simulation on different types of wind generators are analyzed and the results prove that Doubly fed induction generators are expedient. • The Wind energy conversion system is a blooming technology in the field of research area to meet the energy demands in the world. • The article focuses on performance study of the proposed Reboost converter on the different wind energy conversion systems. • According to the literature survey and the simulation results attained, it had been concluded in the article the proposed converter with Doubly fed Induction Generator bestows the better performance on comparison with Permanent Magnet Synchronous Generator and Squirrel Cage Induction Generator. • The circuit description of the proposed converter along with its modal circuit had been elaborated in the article. • The Simulation Circuit Schematic of Reboost Converter with Utility Grid for PMSG, SCIG and DFIG based WECS are embraced with its performance study and its values are verified experimentally.

A Review of Total Harmonic Distortion Factors for the Measurement of Harmonic and Interharmonic Pollution in Modern Power Systems

Harmonic distortion is one of the disturbances that most affects the quality of the electrical system. The widespread use of power electronic systems, especially power converters, has increased harmonic and interharmonic emission in a wide range of frequencies. Therefore, there are new needs in the measurement of harmonic distortion in modern electrical systems, such as measurement in the supra-harmonic range (>2 kHz) and the measurement of interharmonics. The International Electrotechnical Commission (IEC) standards define new total harmonic distortion (THD) rates based on the concept of frequency groupings. However, the rates defined in the IEC standards have shortcomings when measuring signals such as those present in the outputs of power systems with abundant interharmonic content and presence of components in the supra-harmonic range. Therefore, in this work, a comparison is made between the different THD factors currently defined, both in the literature and in the standards, to show which of them are the most suitable for assessing harmonic and interharmonic contamination in power system signals such as those present at the output of inverters.

Corrected similarity laws of stiffened panels considering geometric distortion under low speed impact load

In the experiment of scaled models to dealing with the impact of large structures, the strain rate hardening effect can cause large differences between dynamic responses of prototype structure and scaled models. It is almost impossible to completely scale models due to manufacturing restrictions. In the present study, a corrected method based on VSG (V represented initial impact velocity, S represented dynamic flow stress and G represented impact mass) system is developed through Buckingham-Π theorem. The dimensionless analysis focus on factors related to energy absorption, in which the static moment of the cross-section is regarded as the dominant one. Through introducing the corrected velocity factor βv which considered the strain rate hardening effect and geometric distortion, experimental and numerical tests are established and consistent results show the method is effective to relate dynamic responses of scaled models even with distortion to the prototype structure. Additionally, as the distortion factor affects scaled models design greatly, the sensitivity of geometry distortion is discussed and it is shown that a more notable difference occurred when scaled models under the negative βD. Furthermore, it is confirmed in the paper that although exact similitude is not generally possible through the Cowper-Symonds constitutive model, good accuracy is nevertheless achievable regardless of structure facture.

Harmonics resonance elimination technique using active static compensation circuit

The existence of nonlinear loads produces high distortion and low power factor in the power system that leads to get poor power quality. Resonance problem is occurred due to the power system inductances and the compensation capacitors which increases the harmonic distortion. Therefore, it is necessary to prevent the action of resonance even if conventional or modern methods are built to improve the power system quality. In this paper, active static compensation circuit is proposed and designed to have the features of improving power factor, reducing THD, and eliminating the harmonics resonance effect at the same time with different linear and nonlinear load conditions. These features have been performed based on a modified pulse width modulation technique to drive and control the proposed circuit. The originality designed point of this technique is to have ability to operate the active static compensation circuit as harmonics injector, power factor corrector and resonance eliminator at the same time. Simulation model results illustrate that the proposed circuit is effective for both steady-state and transient operations conditions. The THD of the supply voltage and current at firing angle (α=300) is reduced by 99% and 98.8% respectively. While the power factor is improved to stay around unity.

Stochastic modeling of the polygonal microstructures of alloys using representative microscopic images

This paper proposes an algorithm to generate a statistically equivalent microstructure of alloys for polygonal mesh-based finite element modeling. Morphological and crystallographic characteristics obtained from scanning electron microscopy images of 2D surface slices are employed to generate the mesh. Titanium alloy microstructures are considered as an example to demonstrate the proposed method. The mean and standard deviation of the grain area distribution obtained from the images are employed as the statistical parameters. The algorithm uses the image data and applies perturbation using a distortion factor and Voronoi tessellation to generate the statistically equivalent polygonal microstructure that captures the randomness of grain shape and size iteratively. The grain area distribution of the simulated microstructure closely matches with the actual distribution. Lower-order elements (quadrilateral) on the domain boundary get introduced that may create artifacts when analyzed with the finite element method. A method to eliminate these artifacts is presented with an analysis of stress concentrations occurring due to grain orientation mismatch. Effective mechanical properties, deformation, and fracture behavior as a function of various microstructural parameters like grain area and crystallographic orientations can be analyzed using the polygonal finite element mesh.