Transformation Frequency Research Articles

Enhancing Detection of Malicious Traffic Through FPGA-Based Frequency Transformation and Machine Learning

Enhancing Detection of Malicious Traffic Through FPGA-Based Frequency Transformation and Machine Learning

Neural networks and damage pattern recognition in power transformer diagnostics

The results of detecting deformations and damage of power transformer windings using the transformer Frequency Response Analysis (SFRA) are presented taking into account RG CIGRE A2.26, Standard IEC 60076-18, Standard IEEE C57.149. The technology of pattern recognition by signal images for diagnostics of winding damage, type of defect, its localization is implemented. Neural networks are used - where in a multilayer perceptron with backpropagation of error - the work of neurons in a hierarchical network is imitated. Parametric methods - such as the Naive Bayes classifier - a probabilistic classifier based on the Bayes formula with the assumption of independence of features among themselves for a given class, which greatly simplifies the classification task due to the assessment of one-dimensional probability densities instead of one multidimensional. An algorithm for recognizing patterns of defects and damage to power transformers using the results of diagnostics by the FRA method has been developed.

Drought stress enhances the efficiency of floral dip method of Agrobacterium-mediated transformation in Arabidopsis thaliana.

The Agrobacterium-mediated floral dip protocol is the most extensively used transformation method for a model plant Arabidopsis thaliana. Several useful methods for Agrobacterium tumefaciens-mediated transformations of Arabidopsis are existing, but they are time consuming and with low transformation efficiency. Here, we developed a transgenic Arabidopsis lines TET12p::TET12-RFP in a short period of time and enhanced transformation efficiency by using a modified transformation method by applying drought stress after floral dip. In this protocol, Agrobacterium cells carrying TET12p::TET12-RFP recombinant vectors were resuspended in a solution of 5% sucrose, 0.05% (v/v) silwet L-77 to transform female gametes of developing Arabidopsis inflorescences. Treated Arabidopsis were then applied with different levels of drought stresses to stimulate plants for the utilization of maximum plant energy in seed maturation process. The applied stresses achieved the fast maturation of already treated inflorescences while stopped the growing of newly arising untreated inflorescence, thus decreased the chances of wrong collection of untransformed seeds. Consequently, the collected seeds were mostly transgenic with a transformation frequency of at least 10%, thus the screening for positive transformants selection was more advantageous on a selective medium as compared to a classical floral dip method. Within 2-3 months, two hundred of individual transgenic plants were produced from just 10 infiltrated plants. This study concludes that application of drought stresses in a specific stage of plant is a beneficial strategy for achieving the transgenic Arabidopsis in a short period of time with high transformation efficiency.

Measurement Based Linear and Nonlinear Time Invariant Representations for High Voltage Inductive Transformer Frequency Response up to 10 kHz

Measurement Based Linear and Nonlinear Time Invariant Representations for High Voltage Inductive Transformer Frequency Response up to 10 kHz

An adaptive wide-area neuro-fuzzy based controller for variable frequency transformer in damping inter-area oscillations

Due to the dynamic, non-linear, and complex character of large-scale power networks, prolonged inadequately damped low frequency oscillations may develop, leading to loss of synchronisation of generating units. Flexible AC transmission controller when equipped with an appropriate additional damping mechanism offers substantial damping in mitigating these oscillations. In this context, a smart flexible transmission device namely variable frequency transformer (VFT) is integrated into a multimachine power system network to effectively damp low-frequency oscillations. An adaptive model free neuro-fuzzy inference system (ANFIS) based damping controller is developed for VFT in order to damp inter-area oscillations. The ANFIS is a resilient and intelligent system that combines fuzzy logic and neural network capabilities with attributes like robustness, adaptability, speed, and flexibility. The proposed damping controller, which provides additional damping proportionate to the frequency variation, was included into the VFT’s power loop. The controller input is determined as the center-of-inertia difference of generator rotor speeds and is a remote signal delivered by a wide-area measuring system. Depending on the observability of crucial modes, participation factor (PF) investigation is used to extract the appropriate feedback signal, which provides details on the overall the system’s dynamics. The ANFIS-based scheme for the VFT is designed to impart sufficient damping qualities to the critical modes of the examined system under a variety of operating conditions. Using extensive non-linear time-domain simulations and eigenvalue analysis, the effectiveness of the suggested technique was evaluated on a popular 2-area, 4-generator, 11-bus test system.

Modelling for Multiport Converter-based Hybrid Power supply for Renewable Energy Source Application

This research work deals with the design, modeling and technical evaluation of multiport modular converter based hybrid Power supply using solar PV for small village. The village’s maximum power demand is 50kvA, consisting of demands of twenty (20) households. The first converter in the proposed multiport system is a high frequency isolated DC-DC converter fed with HVDC link yielding an output voltage of 700vDC. The isolated DC-DC converter uses a medium frequency transformer with primary and secondary side converters in input-series output-parallel (ISOP) configuration. Also, the output of first converter is connected to a solar PV and battery system through a buck-boost converter. The second converter in the system is solar PV fed three phase modular inverter designed to have output AC line voltage of 0.415 kV. The three phase inverter is based on modular multilevel converter (MMC) with interleaved modulation techniques. A silicon carbide power MOSFETs, with model numbers CPM3-10000-0270(CREE) and SD11703 (Solitron) are used as a building blocks for isolated DC-DC converter. On the other hand, SiC -MOSFET with part number SCT3017AL (RHOM) is used as basic building block for modular inverter. A solar PV module with open circuit voltage of 85V and maximum power rating of 415W is used to feed the inverter. Different scenarios such as changes in load and changes in solar irradiance are used for critically evaluating the performances of the system under question. The output voltage THD, current distortions, changes in the converter output voltage, current magnitude and converter efficiency are used for performance evaluation of the system under consideration. Simulink/ PLECS (Piecewise Linear Electrical Circuit Simulation) combo simulation platform is used to model and simulate the system in question. Simulation results showed that the proposed multiport converter system can be a viable alternative to low frequency distribution transformer.
 Keywords: Multiport converter, MMC, DC-DC converter, Hybrid power Supply, Solar PV.

Impact of Power Electronic Converter Ripples on Vanadium Redox Flow Batteries

The worldwide effort to decarbonize the electricity grid has made battery energy storage system (BESS) an essential technology. A promising technology for long duration storage on the grid is Vanadium Redox Flow Batteries (VRFBs), which can support the grid by regulating peak load, reducing intermittency of large-scale renewables, and as emergency power supply. There are two primary methods of integrating a BESS to the grid. Frist, the BESS is directly connected to the DC-link of a DC-AC converter that interfaces with the grid. Second, the BESS is connected to a DC-DC converter that in turn interfaces with the DC-link of a DC-AC converter. These converters all have a characteristic ripple voltage and current during operation. The magnitude and frequency of the ripples depend on topology and switching frequency of a converter, controller design and protocol, type of connection to the grid, voltage magnitude and load characteristics. Currently, studies on the impact of ripples have been limited to Lithium-ion and Lead-Acid batteries. The impact of ripple current and voltage has not been studied in VRFBs. In a VRFB, potential impact includes excessive gassing of hydrogen and carbon corrosion of the bipolar plate and porous electrode and cell heating. To better integrate and operate VRFBs to the electricity grid, the impact of ripples needs to be studied in detail.Using a novel experimental platform, where both magnitude and frequency of ripples will be incorporated, we will emulate the performance of different power electronic converter configurations. It will comprise standard 5cm2 VRFB cells with a carbon felt electrode and Nafion ion exchange membrane. The various converter ripples in an electricity grid setting will be emulated by superimposing the signals from a potentiostat (constant current) and a high frequency transformer (modulated ripples), which will be connected to the cathode of the cells.The experimental testbed will be used to cycle the VRFB cells at various states of charge with ripples that emulate the performance of power electronic converters during grid operations and disturbances. Varied parameters will include ripple amplitude, ripple frequency, electrolyte flow rate, applied current density and state of charge. Measurement data from monitoring voltage of each electrode, cell voltage and current, gas generation, electrolyte crossover and electrolyte loss will be analyzed to determine the impact of ripples on VRFB cells. Finally, the cells will be monitored for signs of gas generation and postmortem signs of carbon corrosion.Our analysis will determine the impact of various ripple magnitude and frequencies on VRFBs in a simulated grid integration environment. This work will facilitate the development of design standards for power electronic converters that are intended for battery applications, while also informing future efforts to optimize VRFB cell and stack performance.

Antibiotic resistance transmission risks in water after the disinfection with activated persulfate through Fe/C micro electrolysis and UVA/LED irradiation

Recently, there has been increasing attention about the inactivation of antibiotic resistant bacteria (ARB) using activated persulfate (PS). However, little information could be found on antibiotic resistance (AR) transmission risks after ARB inactivation under activated PS. Batch experiments were conducted to investigate target ARB (E. coli K-12 carrying blaTEM, tetR and aphA) inactivation during the disinfection with activated PS using Fe/C micro electrolysis and UVA/LED irradiation, showing that ARB inactivation was 5.3 log reduction after 60 min of the disinfection with Fe/C activation of PS under acidic conditions (pH 5), which was larger than the one (4.7 log reduction) for the activated PS through UVA/LED. ARB inactivation mechanisms exploration implied that both O2•- and 1O2 were predominant reactive oxygen species (ROS) for ARB inactivation. There was more ARGs conjugation transfer frequency (2.0 ×10−4) after 20 min disinfection of activated PS with UVA/LED, compared with that (2.8 ×10−5) of the disinfection with Fe/C activation of PS. In contrast, AR transformation frequency after the disinfection by Fe/C activation of PS was slightly higher than the one after the disinfection by UVA/LED activation of PS, which was in line with profiles of intracellular ROS and ARB membrane permeability. Furthermore, ARB was completely inactivated after 40 min of the disinfection with the combination between UVA/LED and Fe/C for the activation of PS, indicating that the mentioned combination system could be feasible and desirable to block the risk of AR transmission in this study.

Analytic Design Technique for 2D FIR Circular Filter Banks and Their Efficient Implementation Using Polyphase Approach.

This paper proposes an analytical design procedure for 2D FIR circular filter banks and also a novel, computationally efficient implementation of the designed filter bank based on a polyphase structure and a block filtering approach. The component filters of the bank are designed in the frequency domain using a specific frequency transformation applied to a low-pass, band-pass and high-pass 1D prototype with a specified Gaussian shape and imposed specifications (peak frequency, bandwidth). The 1D prototype filter frequency response is derived in a closed form as a trigonometric polynomial with a specified order using Fourier series, and then it is factored. Since the design starts from a 1D prototype with a factored transfer function, the frequency response of the designed 2D filter bank components also results directly in a factored form. The designed filters have an accurate shape, with negligible distortions at a relatively low order. We present the design of two types of circular filter banks: uniform and non-uniform (dyadic). An example of image analysis with the uniform filter bank is also provided, showing that the original image can be accurately reconstructed from the sub-band images. The proposed implementation is presented for a simpler case, namely for a smaller size of the filter kernel and of the input image. Using the polyphase and block filtering approach, a convenient implementation at the system level is obtained for the designed 2D FIR filter, with a relatively low computational complexity.

Loss Analysis of Nanocrystalline Cores for High Frequency Transformer in Power Electronics Circuits

Loss Analysis of Nanocrystalline Cores for High Frequency Transformer in Power Electronics Circuits

Transplastomic plants — new approaches to solving “old” problems

Transplastomic plants are capable to accumulate the significant amounts (up to 70% of TSP) of target recombinant proteins in tissues. However, the production of such forms is severely limited by the low yield of initial transformants. This problem requires the development and optimization of new approaches to the delivery of transgenes into chloroplasts and an increase in the frequency of their integration into the plastome. Transplastomic tobacco plants expressing thegfpreporter gene and theaadAselectable marker under the control of thePrrnG10Lpromoter and theTpsbAterminator were obtained in the laboratory of plant bioengineering. It is known that the selected promoter and insertion region (between the tRNA genes of isoleucine and alanine) are capable to provide a high yield of recombinant proteins in the leaves of transplastomic plants [1]. However, the content of recombinant GFP in the leaves of the obtained transplastomic plants was determined at the level of 0.12%, and the variability for this trait was minimal and ranged from 0.09 to 0.16% of TSP. Insufficient accumulation of the target protein in transformants is not associated with transcription disorders or the presence of non-transgenic copies of the plastome. Probably, the low frequency of transformation and the lack of variability between the transformants are the reasons that make it difficult to select highly productive forms. It is proposed to increase the efficiency of targeted delivery of genetic constructs to plastids using single-walled carbon nanotubes loaded with recombinant DNA. This process can also be facilitated by our proposed approach to increase the frequency of DNA double-strand breaks in target regions of the plastome through the use of the CRISPR-Cas9 genome editing system.
 This work was supported by the Russian Science Foundation grant No. 23-24-00545.

On-Line Monitoring of Maximum Temperature and Loss Distribution of a Medium Frequency Transformer Using Artificial Neural Networks

On-Line Monitoring of Maximum Temperature and Loss Distribution of a Medium Frequency Transformer Using Artificial Neural Networks

Determination of Parasitic Capacitance of High-Power Medium Frequency Transformers: Case Study of a High Voltage DC Biased Transformer for Wind Power Application

Determination of Parasitic Capacitance of High-Power Medium Frequency Transformers: Case Study of a High Voltage DC Biased Transformer for Wind Power Application

Nuclear Transformation of the Marine Pennate Diatom Nitzschia sp. Strain NIES-4635 by Multi-Pulse Electroporation.

Nitzschia is one of the largest genera of diatoms found in a range of aquatic environments, from freshwater to seawater. This genus contains evolutionarily and ecologically unique species, such as those that have lost photosynthetic capacity or those that live symbiotically in dinoflagellates. Several Nitzschia species have been used as indicators of water pollution. Recently, Nitzschia species have attracted considerable attention in the field of biotechnology. In this study, a transformation method for the marine pennate diatom Nitzschia sp. strain NIES-4635, isolated from the coastal Seto Inland Sea, was established. Plasmids containing the promoter/terminator of the fucoxanthin chlorophyll a/c binding protein gene (fcp, or Lhcf) derived from Nitzschia palea were constructed and introduced into cells by multi-pulse electroporation, resulting in 500μg/mL nourseothricin-resistant transformants with transformation frequencies of up to 365 colonies per 108 cells. In addition, when transformation was performed using a new plasmid containing a promoter derived from a diatom-infecting virus upstream of the green fluorescent protein gene (gfp), 44% of the nourseothricin-resistant clones exhibited GFP fluorescence. The integration of the genes introduced into the genomes of the transformants was confirmed by Southern blotting. The Nitzschia transformation method established in this study will enable the transformation this species, thus allowing the functional analysis of genes from the genus Nitzschia, which are important species for environmental and biotechnological development.

Optimization of the regeneration and Agrobacterium-mediated transformation in pear

Conventional breeding in pears is inefficient due to a long juvenile phase and self-incompatibility. Genetic transformation offers a promise to expedite the breeding process. However, the frequencies of regeneration and genetic transformation in most Pyrus spp. are relatively low. This study investigated various factors influencing regeneration and genetic transformation using leaves from Pyrus ussuriensis Maxim “Shanli” and P. communis L. “Conference” as explants. The optimum regeneration medium for “Shanli” and “Conference” was NN69 containing 3.0 mg L−1 thidiazuron (TDZ) and 0.3 mg L−1 indolybutyric acid (IBA) for the former or 1.0 mg L−1 TDZ and 0.5 mg L−1 naphthalene acetic acid (NAA) for the latter. Sectioning the leaves from 30-day-old plantlets transversely and placing them with their abaxial side facing downward could significantly improve the regeneration ratio in both accessions. Moreover, a two- or four-week culture under the dark was beneficial for the regeneration of “Shanli” and “Conference” respectively. The optimal infection time was 12 and 8 min, while the time of the delayed screening test was two and one day for “Shanli” and “Conference” respectively. Moreover, a coculture of two days was recommended for both accessions. Post-transformation, the optimal concentrations of antibiotics were 16 mg L−1 kanamycin (Kan), 150 mg L−1 timentin (Tim), and 300 mg L−1 cefotaxime (Cef). The optimized regeneration and transformation system can be an effective alternative for either gene function analysis or genetic improvement in pear.

Agrobacterial Transformation Enhancement by Improved Competent Cell Preparation and Optimized Electroporation.

The introduction of plasmids into Agrobacterium cells is one of the key steps in the Agrobacterium-mediated transformation of plants for gene editing applications. Depending on chromosomal background, some Agrobacterium strains exhibit a very low transformation efficiency, which results in a low number of colonies for subsequent screening and thus limits the potential for automated high-throughput transformation processes, especially with low copy or large plasmids. This study demonstrates improvements of transformation frequency by modifying the competent cell preparation process and optimizing electroporation parameters for two Agrobacterium strains. The competent cell preparation process was modified by prolonging bacterial growth in the log phase and optimizing the endpoint cell density for cell harvest which resulted in a significant cell yield increase and transformation frequency improvement. Optimization of electroporation by fine-tuning the parameters not only resulted in a 30-fold transformation frequency increase but also revealed a strain-dependent requirement for field strength and electric pulse length. To further improve transformation of a recalcitrant strain, different concentrations of dimethyl sulfoxide (DMSO) in recovery medium were examined. The study revealed an important role of DMSO in transformed cell recovery, with 5% DMSO resulting in the highest transformation frequency. The significant improvements in Agrobacterium transformation frequency addressed a critical bottleneck towards establishing a high throughput process.

Reconfigurable bandpass filter with flexible tuning of both center frequency and bandwidth

This paper proposes a novel reconfigurable filter that can flexibly tune both the center frequency and bandwidth simultaneously. This reconfigurable filter consists of a filter network with Chebyshev properties and a parallel resonator. These two structures are symmetrical and can be analyzed using the odd-even mode analysis method for the filtering network. With the addition of a tuning factor, the Chebyshev filter network provides a shift in passband and coupling coefficients that can be adjusted to maintain a stable bandwidth; the parallel resonators will produce adjustable transmission zeros on either side of the passband, providing good out-of-band rejection when adjusting the bandwidth and center frequency. By using the transformation of the resonant frequency of two filtering networks, filters of different orders can also be achieved. This reconfigurable filter can achieve continuous bandwidth and center frequency adjustment and can maintain a constant absolute bandwidth during the center frequency adjustment process, with flexible tuning methods. Through simulation and experiments, it has been proven that this reconfigurable filter has a tunable frequency coverage range of 0.4GHz to 2GHz, with a large tunable range.

A facile Agrobacterium-mediated transformation method for the model unicellular green algae Chlamydomonas reinhardtii

A reliable and simple Agrobacterium-mediated transformation system for the unicellular green algae model organism Chlamydomonas reinhardtii has been developed. The protocol has been successfully employed with both neomycin phosphotransferase II (nptII) and the phleomycin resistance (bleI) genes coupled with the selective agents paromomycin and zeocin, respectively. A set of binary vectors were assembled that carry the selectable marker cassettes under control either of the Rbcs2 alone or fused to the HSP270A leader sequence, PsaD, or ß-tubulin2 promoters. The corresponding T-DNA elements also harbored a cassette with a codon-optimized version of yellow fluorescence protein (YFP) under control of the Rbcs2 promoter in which the YFP open reading frame was interrupted with the first intron of Rbcs2 to prevent expression in Agrobacterium tumefaciens. The resultant binary vectors were introduced into A. tumefaciens strain C58C1/pMP90, and the derived transconjugants were used for transformation studies with the walled C. reinhardtii strain CC124. Estimated transformation frequencies ranged from 0.09 to 2.86 colonies per 106 cells inoculated. Molecular characterizations on a subset of the transgenic lineages revealed that most of the transgenic events harbored single locus insertions. Moreover, sequencing of captured junction fragments about the T-DNA insertion site showed that minimal disruption of the C. reinhardtii genome occurred. However, the transgenic lineages often harbored truncated T-DNA regions within the non-selectable marker gene cassettes.

Visible light-driven C/O-g-C3N4 activating peroxydisulfate to effectively inactivate antibiotic resistant bacteria and inhibit the transformation of antibiotic resistance genes: Insights on the mechanism

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) dissemination within water pose a serious threat to public health. Herein, C and O dual-doped g-C3N4 (C/O-g-C3N4) photocatalyst, fabricated via calcination treatment, was utilized to activate peroxydisulfate (PDS) to investigate the disinfection effect on tetracycline-resistant Escherichia coli and the transformation frequency of ARGs. As a result, approximately 7.08 log E. coli were inactivated, and 72.36 % and 53.96 % of antibiotics resistance gene (tetB) and 16 S rRNA were degraded respectively within 80 min. Futhermore, the transformation frequency was reduced to 0.8. Characterization and theoretical results indicated that C and O doping in g-C3N4 might lead to the electronic structure modulation and band gap energy reduction, resulting in the production of more free radicals. The mechanism analysis revealed that C/O-g-C3N4 exhibited a lower adsorption energy and reaction energy barrier for PDS compared to g-C3N4. This was beneficial for the homolysis of O-O bonds, forming SO4•− radicals. The attack of the generated active species led to oxidative stress in cells, resulting in damage to the electron transport chain and inhibition of ATP production. Our findings disclose a valuable insight for inactivating ARB, and provide a prospective strategy for ARGs dissemination in water contamination.

Design and implementation of a Central-Tapped Medium Frequency Transformer with nanocrystalline core for high-efficiency DC-DC SAB converters

A design methodology for medium frequency transformers, which considers a central tap in its secondary winding, is thoroughly presented in this paper. Topologies such as SAB (Single-Active Bridge), PSFB (Phase Shift Full Bridge), and DAB (Dual Active Bridge) can be implemented using this type of transformer for nowadays applications. The design and implementation of a Central-Tapped Medium Frequency Transformer (CT-MFT) is carried out and it is tested as part of a SAB topology. Differently to other proposals, the equivalent model of the CT-MFT was thoroughly defined and verified in the simulation and a tailor-made design methodology is presented. As result, the CT-MFT prototype achieve 99.49 % efficiency which demonstrate the usefulness and efficacy of the proposed methodology. The experience gained in developing this advanced design procedure opens the possibility of further improving isolated unidirectional and bidirectional DC-DC converter topologies in aspects such as efficiency and reliability.