Miracle-dz/UniFAR-FTUs huggingface dataset:
Moduli spaces of topological solitons

This thesis presents a detailed study of phenomena related to topological solitons (in $2$-dimensions). Topological solitons are smooth, localised, finite energy solutions in non-linear field theories. The problems are about the moduli spaces of lumps in the projective plane and vortices on compact Riemann surfaces. Harmonic maps that minimize the Dirichlet energy in their homotopy classes are known as lumps. Lump solutions in real projective space are explicitly given by rational maps subject to a certain symmetry requirement. This has consequences for the behaviour of lumps and their symmetries. An interesting feature is that the moduli space of charge $3$ lumps is a $7$- dimensional manifold of cohomogeneity one. In this thesis, we discuss the charge $3$ moduli space, calculate its metric and find explicit formula for various geometric quantities. We discuss the moment of inertia (or angular integral) of moduli spaces of charge $3$ lumps. We also discuss the implications for lump decay. We discuss interesting families of moduli spaces of charge $5$ lumps using the symmetry property and Riemann-Hurwitz formula. We discuss the K\"ahler potential for lumps and find an explicit formula on the $1$-dimensional charge $3$ lumps. The metric on the moduli spaces of vortices on compact Riemann surfaces where the fields have zeros of positive multiplicity is evaluated. We calculate the metric, K\"{a}hler potential and scalar curvature on the moduli spaces of hyperbolic $3$- and some submanifolds of $4$-vortices. We construct collinear hyperbolic $3$- and $4$-vortices and derive explicit formula of their corresponding metrics. We find interesting subspaces in both $3$- and $4$-vortices on the hyperbolic plane and find an explicit formula for their respective metrics and scalar curvatures. We first investigate the metric on the totally geodesic submanifold $\Sigma_{n,m},\, n+m=N$ of the moduli space $M_N$ of hyperbolic $N$-vortices. In this thesis, we discuss the K\"{a}hler potential on $\Sigma_{n,m}$ and an explicit formula shall be derived in three different approaches. The first is using the direct definition of K\"ahler potential. The second is based on the regularized action in Liouville theory. The third method is applying a scaling argument. All the three methods give the same result. We discuss the geometry of $\Sigma_{n,m}$, in particular when $n=m=2$ and $m=n-1$. We evaluate the vortex scattering angle-impact parameter relation and discuss the $\frac{\pi}{2}$ vortex scattering of the space $\Sigma_{2,2}$. Moreover, we study the $\frac{\pi}{n}$ vortex scattering of the space $\Sigma_{n,n-1}$. We also compute the scalar curvature of $\Sigma_{n,m}$. Finally, we discuss vortices with impurities and calculate explicit metrics in the presence of impurities.
A Genetic Algorithm-Based Approach to Identify Near-Optimal Non-Equidistant Checkpointing Strategies

Software intensive systems rely on checkpointing to prevent loss of computation, by performing periodic backups. Non-equidistant checkpointing strategies have been proposed for specialized hardware and software applications as well as specific failure distributions. However, a general method to identify a non-equidistant checkpointing strategy for an arbitrary combination of application and failure distribution would be beneficial. This paper proposes an approach to identify a near optimal non-equidistant checkpointing strategy with a genetic algorithm, which only requires knowledge of the failure distribution. Experiments suggest that the approach consistently outperformed the traditional strategy of equidistant checkpoints under (i) a range of total processing times and (ii) different values of distributions exhibiting increasing, constant, and decreasing failure rates.
Hierarchical control architecture for networked synchronization of multi-microgrids

A hierarchical control architecture for networked synchronization of multi-microgrids based on dispatchable virtual oscillator control (dVOC) is proposed, including steady-state control layer and dynamic control layer. The steady-state control layer can realize that the operating frequency of each sub-microgrid is consistent and the phase and amplitude of the voltage at point of common coupling (PCC) reach the set values, so that the whole multi-micro grid system converges to the stable operation point associated with the specific power scheduling instruction. The dynamic control layer can realize the fast and accurate regulation of the PCC voltage, frequency and phase of each sub-microgrid and ensure the high-precision distribution of output power of each distributed generation (DG) inside. The proposed control architecture realizes the flatness of the multi-microgrid control, avoids the restriction of the multi-layer control structure on the dynamic performance of the system, reduces the communication complexity to a certain extent and improves the reliability of the system. The effectiveness of the proposed hierarchical control architecture is verified by simulation experiments.
Influence of Active Antennas on EMF Restrictions in 5G Base Stations Deployment

In this paper, a model to analyse the influence of active antennas on ElectroMagnetic Field restrictions in 5G base stations deployment is presented. The model (based on simulations via CST) allows for the computation of exposure in the vicinity of base stations with active 5G antennas in order to compute the respective exclusion zone that enables the safety of the population, taking realistic maximum power levels. Representative scenarios with co-location of antennas from several systems (from 2G to 5G) are analysed. For an urban scenario, the exclusion zone is reduced from 25.2 m to 16.4 m, when proper exposure conditions are taken into account.
Exploring modern alternatives to the Whittaker-Shannon-Nyquist sampling theorem in THz Spectroscopy

We present simulations for a THz cross-correlation spectroscopy (THz-CCS) optical system. The aim is using compressed sensing (CS) to reconstruct the THz signal from a random under sampling of the signal and potentially replacing a delay stage unit of the THz-CCS system to increase robustness and cost-effectiveness of the optical system. We present results from using the CS to attempt to reduce the number of samples required to interpolate the THz signal in question. We compared Shannon-Whittaker interpolation to CS reconstruction in a multitude of basis. We conclude that within the current implementation of CS Shannon-Whittaker interpolation beats CS for our simulated THz signal. We have however only just begun to explore the multitude of potential CS implementations for THz spectroscopy systems and see a host of additional explorations to be conducted in the near future.
High-Performance Digital Multiloop Control of LLC Resonant Converters for EV Fast Charging With LUT-Based Feedforward and Adaptive Gain

The LLC resonant converter is typically adopted in battery charging applications due to its excellent performance in terms of efficiency, power density, and wide input/output voltage regulation. However, this converter is a complex high-order system characterized by a strong nonlinear behavior, featuring large variations of the small-signal gain/phase and pole location depending on the operating point. Consequently, these features pose substantial challenges in designing a closed-loop controller and providing constant dynamical performance over a wide operating range. Therefore, this article proposes a digital multiloop control strategy for LLC resonant converters ensuring constant closed-loop bandwidth and excellent disturbance rejection performance across the complete converter operating region. The control scheme consists of two cascaded voltage and current loops. To design and tune these controllers, a simplified LLC dual first-order small-signal model is proposed. The system nonlinear behavior affecting the current control loop is counteracted by a real-time controller gain adaptation process, which ensures constant control bandwidth. In particular, the adaptive gain values are provided by a static switching frequency lookup table obtained experimentally. Moreover, the steady-state switching frequency value is fed forward at the output of the current loop regulator, providing a further dynamical performance enhancement. The proposed control strategy and the controller design procedure are verified both in simulation and experimentally on a 15-kW LLC converter prototype. The results demonstrate the superior reference tracking and disturbance rejection performance of the proposed control strategy with respect to a state-of-the-art solution based on a proportional–integral regulator.
On the Non-invasive Sensing of Arterial Waveform and Hematocrit using Microwaves

Arterial waveforms can provide valuable insights into a patient’s health. Hematocrit (HCT) level, the blood volume concentration of red blood cells, makes up 40 to 50% of the total blood concentration. Dielectric spectroscopy studies focusing on blood have shown that relative permittivity and conductivity vary with HCT levels. This paper presents a novel method to detect the hematocrit levels in the blood and sense the arterial waveform. A finite-difference time-domain (FDTD)-based 2D electromagnetic (EM) simulation with an artery and tissue model was used to detect different HCT levels at 915 MHz. Based on published literature, dielectric parameters for a normal range of HCT levels were assumed from animal blood studies. Additionally, a 2D wrist simulation model was developed at 915 MHz and 2.45 GHz with a multiple-port system. Based on numerical simulations, EM signals were sensitive to different HCT levels and changes in arterial blood volume. The simulation results indicate a great potential for microwave-based non-invasive sensing of HCT levels and arterial waveforms.
Mm-wave 3D-printed DRAs for Cost-effective Emerging 5G- and SatCom Applications

This paper presents a demonstration for low cost dielectric resonator antenna (DRA) manufacturing, using 3D-printing technology for mm-wave applications. DRAs are high-efficient radiators, as compared to metallic antennas, especially at high frequency applications. Moreover, 3D-printing technology facilitates DRA machining and positioning on the printed circuit board. Two DRAs, designed at 20 GHz, and 30 GHz, are 3D-printed, and measured realizing good performance.
A New Multi-objective Hybrid Algorithm For Dynamic Environmental Economic Dispatching Of Power System

Dynamic economic environment dispatch is a common multi-variable, strongly constrained, non-convex multi-objective optimization problem in power systems, and traditional algorithms are difficult to solve. Therefore, an improved IMOSSA-DE multi-objective optimization algorithm. First, initialize the population with a chaotic map to improve the quality of the initial solution, and increase the diversity of the population. In order to further strengthen the discovery and development ability of the discoverer, the sine and cosine strategy is introduced. Secondly, the traditional sparrow search algorithm is easy to fall into the local optimal solution, and the convergence performance is poor. The differential evolution strategy is integrated into it can enhance the global search ability and convergence performance of the population. In addition, non-dominated sorting, a new crowding degree distance calculation strategy and elite retention strategy are introduced to make the algorithm capable of solving multi-objective optimization problems. The optimal compromise scheduling scheme is obtained by fuzzy decision theory. Finally, the simulation results of the 10-machine power system show that the proposed algorithm can optimize the two conflicting goals of emission and cost at the same time, and obtains a better Pareto frontier than other algorithms, verifying the effectiveness and superiority of the algorithm.
Hardware Trojan Recognition based on Radiated Emission Characteristics

Hardware Trojans (HT) have become a major threat to the integrated circuit (IC) industry and supply chain due to the many third parties involved in IC manufacturing. Therefore, a reliable hardware Trojan detection method is needed. Since electromagnetic radiation is an inherent phenomenon in the operation of electronic equipment, there are differences in the electromagnetic radiation characteristics for circuits with different structures and operating states. In this paper, we propose a novel method to detect hardware Trojan by using the difference of electromagnetic radiation. A hardware Trojan is considered to exist when the difference between the electromagnetic radiation of the suspect IC and that of the genuine IC in the specified mode is greater than the threshold. Experiments of detecting hardware Trojan in FPGA show that the proposed method can effectively distinguish the difference between the radiation emission of Trojan IC and genuine IC.
Investigation of Conducted Electromagnetic Interference of Three-Level SiC Power Module

In this paper, a 1200-V/200-A three-level silicon carbide (SiC) power module with neutral point clamped (NPC) topology has been investigated in terms of electromagnetic interference (EMI). Compared with traditional two-level SiC modules, the three-level module can effectively alleviate voltage stress of the device, and ensure lower spectrum amplitude of the output terminal voltage below resonance frequency. However, the three-level module presents higher spectrum amplitude in high-frequency (HF) ranges (above 10 MHz) due to the aggravated switching ringings. As a result, RC snubber circuit is required to mitigate such ringings and reduce spectrum amplitude for three-level module. According to relative experimental results, it can be figured out that the three-level NPC power module combined with RC snubber circuit can suppress switching ringings, which is critical for reducing the level of conducted EMI.
Modeling of EMI Filter by Means of Recurrent Neural Network with Encoding Layer

In order to solve the electromagnetic interference (EMI) problems caused by high-speed switching of power electronic devices, EMI filters are widely used. However, the design of EMI filter is a time consuming and costly process. This letter proposes a new modeling method of EMI filter by means of recurrent neural network (RNN) with encoding layer. In this method, mutual coupling between components and topology of EMI filter are taken into account. The accuracy of the method is verified through comparing simulated and measured results of insertion loss of EMI filter. Compared with the traditional modeling method and other neural network-based methods, the proposed modeling method is more accurate and efficient under conditions of relatively small experimental data size.
A Novel Circuit Modeling Approach for Electromagnetic "Black-box" Problems based on Generative Adversarial Networks and Partial Element Equivalent Circuit Method

Reconstructing the electromagnetic properties of an unknown electronic component with limited or little information is challenging. In this paper, a new circuit modeling approach for a component in a "black-box" is proposed by tackling nonlinear inverse scattering problems (ISPs). A pixel-to-pixel generative adversarial network (pix2pix GAN) is built to infer the conductor structures within a space of interest from the measured electric/magnetic fields in a near-field region. The circuit model of the component is subsequently generated by the partial element equivalent circuit (PEEC) method based on the derived conductor structures. The proposed pix2pix GAN is developed and optimized according to computational electromagnetics principles and numerical experiment. Learning from a tailored training set that imitates the conducting traces of integrated circuit, the pix2pix GAN confines the solutions to a physically meaningful subset. The proof-of-concept example shows that a well-trained pix2pix GAN can effectively reconstruct conductor structures with high confidence and have excellent agreement with the ground truth.
Timing-Aware Fill Insertions With Design-Rule and Density Constraints

Metal fill insertion has become an essential step in reducing dielectric thickness variation and improving pattern uniformity, which is important in mitigating process variations, thereby achieving better manufacturing yield. However, metal fills could induce coupling capacitance, which is not often considered in existing works that typically focus more on pattern density uniformity, incurring significant problems in timing closure. However, it is a great challenge to consider three types of capacitances (i.e., area, fringe, and lateral capacitances) with design rules and density constraints at the fill insertion stage simultaneously. This article presents an efficient timing-aware fill insertion algorithm for minimizing the total capacitance and fill amount, considering the density constraints. First, we present an initial metal fill insertion and design-rule-aware legalization to obtain an initial fill insertion solution quickly. Second, from critical conductors to powers/grounds in a circuit, we divide conductors into different equivalent paths and then construct a capacitance graph to reduce the capacitance of each equivalent path globally. Third, we propose a density-aware coupling capacitance optimization method and a fast Monte Carlo-based fill selection to further reduce the coupling capacitance between any pair of conductors. Finally, we present a density-aware fill deletion method to reduce the fill amount. We evaluate the performance of our algorithm on the benchmarks of the 2018 CAD Contest at ICCAD and its official contest evaluator. Compared with the first-place team of the contest and the state-of-the-artwork, experimental results show that our algorithm achieves the lowest total capacitance and the least fill amount in a comparable runtime.
2-Inverted U-Slot Integrated Rectangular Patch Antenna Array for S band Applications

In this paper, a 2 inverted U-slot integrated rectangular patch antenna array is proposed that can be used for S band applications i.e., radar applications, communication and wireless networks. In the proposed antenna design 2 inverted U slots are introduced in the patch to improve bandwidth providing a bandwidth of 150 MHz and gain of 4.08 dBi resonating at 3.3 GHz. Furthermore, 4 X 4 antenna array is fabricated on 1.6 mm thick FR4 substrate with dielectric constant 4.4 providing a gain of 14.2 dBi. Ansys HFSS is used for antenna simulation and a prototype is fabricated and tested.
The Wavelet-Modulation Technique for $3\phi$, 5-Level, Power Electronic Converters—Part I: Development and Testing

This work extends the wavelet modulation (WM) technique for operating three-phase (<inline-formula><tex-math notation="LaTeX">$3\phi$</tex-math></inline-formula>), five-level (5L) power electronic converters (PECs). The WM technique is extended by resolution segmentation of the synthesis scale-based linearly combined wavelet functions, which are used as switching signals. The resolution segmentation is created based on the dilation property of synthesis scale-based linearly combined wavelet functions. Each leg of the <inline-formula><tex-math notation="LaTeX">$3\phi$</tex-math></inline-formula> VS, 5L dc–ac PEC is operated by two sets of resolution-segmented synthesis scale-based linearly combined wavelet basis functions to produce the voltage of one phase. The extended WM technique is implemented for performance testing, when operating <inline-formula><tex-math notation="LaTeX">$3\phi$</tex-math></inline-formula> VS, 5L, diode-clamped and flying-capacitor dc–ac PECs. In this article, Part I, simulation test results are presented and compared with results obtained using the level-shifted pulsewidth modulation, phase-shifted PWM, and space vector modulation. Test results show significant reductions of output harmonics, along with improvements in fundamental components of output voltages and PEC efficiency.
Band-pass Hairpin Filter Using C-shaped DGS With Wide-band Rejection

A band-pass hairpin filter is proposed that is combined with two C-shaped defected ground structures (DGSs) to provide a wide rejection band. The top layer of the structure consists of a hairpin filter of 5th order, and the bottom layer has DGSs that introduce low-pass filtering. The proposed hybrid circuit has 5 dB of insertion loss and 13 dB of return loss at its center frequency of 1.98 GHz.
On Multilayer Slot Antenna Configurations, equipped with Ridged Gap Waveguide Feeding and Glide Symmetric Holes for 5G mmWave Platforms

We focus on multilayer antennas operating on 39GHz, using the Gap Waveguide Technology. A multilayer 5G antenna is usually comprised of the radiating layer, the resonant cavity, and the feeding network distribution. To reduce the fabrication cost, the cavity layer is comprised of small etched sections, instead of being formed by metallic pins. Also, glide symmetric holes are developed around the cavity layer, to avoid any leakage in the gap between the cavity and radiating layer. Here, for the first time, two different periodic EBG structures (metallic pins in the feeding layer and glide symmetric holes in the cavity and radiation layer) are combined to implement a multilayer antenna. Furthermore, we examine and compare two different configurations of radiating layer, using either a double or single radiating slot array.
A Flush Mount Automobile 4-Channel Universal Antenna Design

This paper presents a flush mount compact vehicle antenna system that supports 4-channel MIMO operation of LTE, 5G sub6, WLAN, and C-V2X communications. Compared to its previous design [1], additional design features were added to cover 5G sub6 band (617-698 MHz). The new design is also recessed into a metallic cavity for supporting flush mount configuration below the roof of the vehicle. Each individual channel produces a directive pattern and the combination of all 4 channels produces a relatively uniform azimuthal pattern in the selection combining MIMO mode. The measurement results of a fabricated prototype are also presented.
Cross Validation of TEMPEST-D and RainCube Observations Over Precipitation Systems

This article presents cross validation of nearly simultaneous observations between the Temporal Experiment for Storms and Tropical Systems-Demonstration (TEMPEST-D) and Radar in a CubeSat (RainCube) satellite microwave sensors over precipitation systems. RainCube senses the atmosphere using a Ka-band nadir-pointing radar, and TEMPEST-D senses using multifrequency millimeter-wave radiometers. Nine precipitation systems were used in this cross-validation study. Occurring over nearly a two-year period, these storms were scattered over many regions of the world from the Tropics to the midlatitudes. A shift correction algorithm was developed to remove the uncertainty between the two sensors’ observations due to the time difference and the storm motion between the two instrument overpasses. Correlation coefficients were calculated between self-normalized, inverted RainCube cumulative reflectivity and self-normalized TEMPEST-D brightness’ temperatures. As expected, these correlation coefficients are consistently higher for the four TEMPEST-D high-frequency channels than for the single low-frequency channel. The shift correction algorithm improved the average correlation coefficient by 19% for the four high-frequency channels and by 58% for the single low-frequency channel. The average correlation coefficient after shift correction is 0.76 for TEMPEST-Ds four high-frequency channels and 0.54 for the single low-frequency channel. The comparisons demonstrated high consistency between the TEMPEST-D and RainCube observations, even though the two microwave sensors’ fundamental physics is different; one is passive, and the other is active.