Presence Of Parasitic Elements Research Articles

Influence of Parasitic Elements on Flyback Converter at High Switching Frequency Operation: A Comprehensive Analysis

The presence of parasitic elements in the flyback converter amplifies the impact on the converter’s primary current quality, particularly when the converter's switching frequency exceeds its designated operational rate. In this paper, the parasitic and stray elements of the transformer have been comprehensively examined, modelled, and simulated to evaluate their influence on the converter, with specific emphasis on the primary current. The simulation was performed utilising MATLAB SIMULINK software, integrating the authentic critical characteristics of the components, and conducting tests at various switching frequencies. The simulation results indicate that the primary current exhibits pronounced resonance effects at higher switching frequencies. The experimental findings are presented to corroborate the theoretical analysis and simulations pertaining to the impact of parasitic elements on the transformer and its immediate environment.

DGS Based CP Antenna for 5G Communication with Harmonic

Higher harmonics in antennas contribute to negative effects on antenna performance such as interference, radiation pattern distortion, impedance mismatch and increased complexity in design, commonly occurring in RF communication systems caused by the non-uniformity of the antenna structure and the presence of parasitic elements. Therefore, a patch antenna operating at 3.65GHz for 5G mobile communication that incorporates techniques to suppress unwanted higher harmonics is presented. The antenna design employs a basic rectangular patch antenna with an inset feed technique to enhance the S11 parameters at the resonant frequency. Additionally, two dumbbell defected ground structures (DGS) are employed to minimize the higher modes of harmonic distortion. To transform the antenna into a circular polarized (CP) antenna, two truncated corners and a cross slot perpendicular to the middle of the patch are introduced. The proposed antenna is able to suppress unwanted harmonics at higher resonances, demonstrating its effectiveness in mitigating harmonic distortion

Design of New High Step-Up DC-DC Converter Topology for Solar PV Applications

A new topology for high step-up nonisolated DC-DC converter for solar PV applications is presented in this paper. The proposed high-voltage gain converter topology has many advantages like low-voltage stress on the switches, high gain with low duty ratio, and a continuous input current. The analytical waveforms of the proposed converter are presented in continuous and discontinuous modes of operation. Voltage stress analysis is conducted. The voltage gain and efficiency of the converter in presence of parasitic elements are also derived. Performance comparison of the proposed high-gain converter topology with the recently reported high-gain converter topologies is presented. Validation of theoretical analysis is done through the test results obtained from the simulation of the proposed converter. For the maximum duty ratio of 80%, the output voltage of 670 V is observed, and the voltage gain obtained is 14. Comparison of theoretical and simulation results is presented which validates the performance of the proposed converter.

Modeling and Experimental Validation of a Single-Phase Series Active Power Filter for Harmonic Voltage Reduction

Research advances on renewable energy systems have increased the interest in the use of isolated power supplies composed of power converters based on high-frequency transformers. Such power equipment generally presents high internal impedance, which amplifies the effects of harmonic voltages produced by nonlinear loads that draw currents with high harmonic content. Some sensitive loads, e.g., electric motors and distribution transformers, may not properly operate when supplied by extremely distorted voltages. Series active power filters (SAPFs) are suitable to mitigate this inconvenient, being capable of providing harmonic voltage compensation and minimizing the distortion of supply voltages. In this context, this work addresses the small-signal modeling, control system implementation, and experimental validation of a single-phase SAPF. The proposed approach is solely employed for harmonic voltage compensation purposes, thus allowing loads to be supplied by a nearly sinusoidal voltage. During the modeling process, the operating steps are analyzed in detail, while the presence of parasitic elements is taken into account. An equivalent circuit is also derived, which is used to provide an easy understanding of the interactions among the SAPF, load, and power supply. From this model, transfer functions can be obtained so that it is possible to design the control loops used by the SAPF. Experimental results with distinct types of loads are presented to evaluate the SAPF performance in both steady-state and transient conditions.

Design of Yagi-Uda array using Particle Swarm Optimization

The optimization of Yagi-Uda antenna is a subject of continuous research since its invention because of its multimodal pattern and complexity due to the presence of parasitic elements. Particle Swarm Optimization (PSO) is a new, high performance evolutionary technique, which has recently been used for optimization problems in antennas and electromagnetics. In this paper, PSO has been used to simultaneously optimize the gain, front-to-back ratio, input resistance and beamwidth of Yagi-Uda array. The antenna array geometry with good performance, compared to the results in available literature, has been obtained.

Giardia and Cryptosporidium in canine faecal samples contaminating an urban area

The aim of the present paper was to continue the study on the presence of parasitic elements in the canine faeces contaminating the urban environment of Naples (southern Italy), focussing on the protozoa Giardia and Cryptosporidium. The total number of sub-areas studied was 143, and the total number of canine faecal samples collected and examined was 415. Each faecal sample was tested for the presence of copro-antigens of Giardia and Cryptosporidium using two commercially available enzyme-linked immunosorbent assays. Giardia antigens were found in 19.6% (28/143) of the sub-areas and in 7.7% (32/415) of the canine faeces collected. Cryptosporidium antigens were found in 4.2% (6/143) of the sub-areas and in 1.7% (7/415) of the canine faeces collected. Co-infection was not found in any sample. The results of the logistic regression models did not show any association between the positivity to Giardia or Cryptosporidium and the independent demographic variables (human population density, male and female population density) taken into consideration. In conclusion, the findings of the present study revealed the presence of Giardia and Cryptosporidium in canine faecal samples from the urban environment of Naples; however, the zoonotic potential of these findings was not assessed due to the lack of information on species/genotypes detected.

Encefalitis amebiana granulomatosa por Balamuthia mandrillaris.: Primer caso diagnosticado en Chile

The case of a 7 month-old baby boy is presented, with a history of several weeks of evolution of personality changes, convulsions and fever. While he was hospitalized, the brain image study showed multifocal cavity lesions, which varied from millimeters to 4 cm of diameter, not producing mass effect. Their biopsy revealed necrotizing encephalitis. In spite of treatment, the lesions progressed and the boy died. The autopsy demonstrated an extensive necrotizing encephalitis with fibrinoid necrotic arteritis, signs of organization, and the presence of parasitic elements with characteristics of trophozoites and cysts of free-living amoebas belonging to the genus Acanthamoeba or Balamuthia. In addition, hypoplasia-dysplasia of the thymus and signs of shock were found. The morphologic elements correspond to the disease described as granulomatous amebic encephalitis and the agent found was identified as Balamuthia mandrillaris (Centers for Diseases Control and Prevention, Atlanta, USA ).

A new measurement method for capacitance transducers in a distance compensated telemetric sensor system

A measurement method for an inductive telemetric system useful for capacitance transducers is described. It is based on a physical model that also considers the leakage and coupled magnetic fluxes and the possible presence of parasitic elements. The model behaviour explains well the measured impedance diagram. Moreover it compensates the change of distance between the read-out and sensing inductors. The method has been experimentally tested showing good agreement with the reference quantities (about 0.6% of the reading value) and compared with a different one. A comparison with a measurement method usually proposed in the literature highlights the distance compensation and the possibility of a more general application. Theoretical explanations, experimental results and discussion are reported.

Pulse forming network optimal design for the power supply of EML launchers

In this paper a procedure for the design of a PFN feeding an electromagnetic launcher is presented. Given the design parameters (pulse duration, pulse rise time, pulse current amplitude and load equivalent resistance), the procedure gives the value of the inductances and capacitances for an optimal design of an L-C ladder feeding network. In the procedure an auxiliary network having all branches in parallel, and each branch formed by a series of a capacitor and an inductor, is used. By means of this auxiliary network which allows a simple expression of its generated current pulse, the equivalent L-C ladder network is deduced. Finally a suitable performance index is considered in order to optimize the obtained network, taking Into account the presence of parasitic elements.

Small efficient axially symmetric dual reflector antennas

Two efficient small dual reflector antenna designs are analyzed using the method of moments. One is based on the standard Cassegrain system and the other is a displaced axis design. Both incorporate a low-blockage feed consisting of a dipole radiating in the presence of parasitic elements. In the first case, efficiencies greater than 55% were obtained for 20-wavelength main reflectors; in the second, an efficiency greater than 67% was achieved for a 22-wavelength main reflector. >

The design of a high-resolution AC parametric tester

We present the design for an automatic wafer-probing ac characterization system that provides 0.1-fF capacitance resolution at the wafer level. The most important difficulties that had to be overcome were: the presence of parasitic elements in the measurement circuit, the design of a probe-card system, and the development of user-friendly system software.

Near-and Far-Field Thin-Wire Coupling - Theory and Expeiment

The method of moments is applied to near-and far-field coupling problems for thin-wire antennas with arbitrary orientation, excitation, and loading. A coupling matrix is derived. The analysis method is validated by the results of an extensive experimental program. Comparisons are made between theory and experiment for coupling from monopole to monopole, dipole to dipole, and dipole to dipole in the presence of parasitic elements. Special approximate formulas are developed for parallel thin-wire dipoles and monopoles. The moment methods permit accurate computation of antenna coupling in a wide variety of situations.