REGULATED TRANSFORMER RECTIFIER UNIT FOR MORE ELECTRIC AIRCRAFTS

The impending trends in the global demand of more-electric-aircrafts with higher efficiency, high power density, and high degree of compactness has opened up numerous opportunities in front of avionic industries to develop innovative power electronic interfaces. Traditionally, passive diode-bridge based transformer rectifier units (TRU) have been used to generate a DC voltage supply from variable frequency and variable voltage AC power out of the turbo generators. These topologies suffer from bulky and heavy low-frequency transformer size, lack of DC-link voltage regulation flexibility, high degree of harmonic contents in the input currents, and additional cooling arrangement requirements. This PhD research proposes an alternative approach to replace TRUs by actively controlled Regulated Transformer Rectifier Units (RTRUs) employing the advantages of emerging wide band gap (WBG) semiconductor technology. The proposed RTRU utilizing Silicon Carbide (SiC) power devices is composed of a three-phase active boost power factor correction (PFC) rectifier followed by an isolated phase-shifted full bridge (PSFB) DC-DC converter. Various innovative control algorithms for wide-range input frequency operation, ultra-compact EMI filter design methodology, DC link capacitor reduction approach and novel start-up schemes are proposed in order to improve power quality and transient dynamics and to enhance power density of the integrated converter system. Furthermore, a variable switching frequency control algorithm of PSFB DC-DC converter has been proposed for tracking maximum conversion efficiency at all feasible operating conditions. In addition, an innovative methodology engaging multi-objective optimization for designing electromagnetic interference (EMI) filter stage with minimized volume subjected to the reactive power constraints is analyzed and validated experimentally. For proof-of-concept verifications, three different conversion stages i.e. EMI filter, three-phase boost PFC and PSFB converter are individually developed and tested with upto 6kW (continuous) / 10kW (peak) power rating, which can interface a variable input voltage (190V-240V AC RMS) variable frequency (360Hz – 800Hz) three-phase AC excitation source, emulating the airplane turbo generator and provide an AC RMS voltage of 190V to 260V. According to the experimental measurements, total harmonic distortion (THD) as low as 4.3% and an output voltage ripple of ±1% are achieved at rated output power. The proposed SiC based RTRU prototype is ~8% more efficient and ~50% lighter than state-of-the art TRU technologies

Agricultural Practices Destroying the Environment

50% of the world\u27s habitable land has been converted for farming (Farming: Habitat Conversion, 2017) Indonesia rain forests have been cleared for the construction of palm oil plantations This threatens the habitats of endangered species such as the Asian elephanthttps://digitalcommons.imsa.edu/unsdg_infographics/1001/thumbnail.jp

Machine Learning and Rule Mining Techniques in the Study of Gene Inactivation and RNA Interference

RNA interference (RNAi) and gene inactivation are extensively used biological terms in biomedical research. Two categories of small ribonucleic acid (RNA) molecules, viz., microRNA (miRNA) and small interfering RNA (siRNA) are central to the RNAi. There are various kinds of algorithms developed related to RNAi and gene silencing. In this book chapter, we provided a comprehensive review of various machine learning and association rule mining algorithms developed to handle different biological problems such as detection of gene signature, biomarker, gene module, potentially disordered protein, differentially methylated region and many more. We also provided a comparative study of different well-known classifiers along with other used methods. In addition, we demonstrated the brief biological information regarding the immense biological challenges for gene activation as well as their advantages, disadvantages and possible therapeutic strategies. Finally, our study helps the bioinformaticians to understand the overall immense idea in different research dimensions including several learning algorithms for the benevolent of the disease discovery

Calculating the Collins-Soper Angle of Simulated Particle Physics Data

The Collins-Soper angle, referred to as cos(ϴ*), measures the angle of the negatively charged lepton in dilepton events with respect to the beam axis. When we reconstruct events that are simulated using Monte Carlo, we sometimes encounter situations where both leptons in the dilepton pair share the same sign. This sign error originates from our particle detector because the curvature of high-energy electrons is hard to measure. However, the calculation of cos(ϴ*) requires the leptons to have opposite signs. Rather than randomly assigning charges to the lepton and antilepton, we determined that we should trust the sign of the particle with the lower pseudorapidity. Instead of guessing correctly half of the time, our new strategy identified the negatively charged leptons at a 70% success rate. Using the modular framework that we built to analyze cos(ϴ*), we have continued to investigate the behavior of our simulated data by looking at acceptance, migration, and mass resolution

Large- and Small-Signal Modeling Derived Loss Optimal Power Loop Decoupling Mechanism of TAB Converter

This article presents a precisely synthesized full order as well as reduced order continuous time large signal and small signal model of a hybrid phase-duty controlled triple-active bridge (TAB) converter based on higher order harmonic frequency inclusive averaging model. Such model helps to accurately predict the steady state circuit parameters such as inductor current, average output voltage, output voltage ripple etc. that in turn can be used to formulate the loss minimized optimal phase-duty modulation strategy for a TAB. Further, the derived full order small signal model can specifically model the high frequency dynamics of the converter which are neglected in the reduced order modeling. Moreover, in order to facilitate decoupled power flow in a TAB, a decoupler network is formulated based on meticulously modeled converter plant considering higher order harmonics of the bridge voltages into calculation. Finally, a controller-based decoupled power management strategy is proposed in this study that decouples the TAB control loops and facilitates faster transient performance with two independent PI controllers. An 800 W TAB converter proof-of-concept is designed, fabricated, and tested to verify the established modeling techniques and the proposed controller decoupling action. With the implementation of the decoupled control under an 80% load transient at the 2nd output port, the experimental results show 30% improvement in overshoot compared to the fundamental harmonic based decoupling method

A Comprehensive Review of EMI Filter Network Architectures: Synthesis, Optimization and Comparison

This paper presents a volumetric comparison among three possible optimized three phase EMI filter structures, a three phase PFC converter used in cutting edge applications, such as avionics, space or shipboard power systems. The size minimization of each of the filter structures, described in the paper, was performed utilizing the volumetric optimization methodology proposed in the paper. This paper theoretically demonstrates the design steps for choosing the appropriate filter component values and number of filter stages to achieve the smallest volume of the DM filter stage for any given EMI filter structure. While the validation of the proposed design methodology was done through a MATLAB simulation, an experimental verification was also performed by designing and comparing the optimized EMI filter structures for a 2.3 kW proof-of-concept of a three-phase boost PFC converter for more electric aircraft (MEA) applications to comply with the stringent EMI requirements of the DO-160F standard

Analysis of the Collins-Soper Angle in Contact Interaction and Large Extra Dimension Monte Carlo Data Samples

Abstract: The Collins-Soper angle θ* is the angle between the negatively-signed lepton and the Z axis in the center of mass reference frame, calculated using Lorentz-invariant kinematic variables. In CI analyses, cosθ* is used to control the lepton angular distributions (as 1 + cosθ), as well as determine forward-backward asymmetry of the dileptons in the sample. The cosθ distribution of a sample is a crater-shaped distribution ranging from -1 to +1, with an asymmetrical shift towards +1 caused by the transverse momentum asymmetries between interacting partons. However, the Collins-Soper calculations can give rise to significant sources of error. One such error of particular importance is the Same-Sign Electron problem. Due to systematic error inherent to event reconstruction, the measured sign of about 5-10% of electrons and positrons is flipped, leading to positrons being labelled as electrons and vice versa. The Collins-Soper Angle calculation is dependent upon proper particle identification, and as such a method for labelling the particles in case of a sign flip is needed. This study aims to determine whether there are significant differences between random assignment, high Pt trusting, low Pt trusting, and other variable-dependent methods by comparing generator-level distributions with the various models of reconstructed distributions. If there are significant differences between methods, the study will determine which method yields the most accurate results