cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
YP Webinar: Resilient and Sustainable Distribution Systems with Advanced Microgrids Slides
Creators: Xiaonan Lu
Publisher: name: IEEE
Year: 2017

PELS Webinar Slides
Microgrids enable an effective solution of enhancing the resiliency of a low inertia distribution system. Especially when facing the faults induced by natural disasters, it is necessary to leverage the capabilities of distributed energy resources (DERs) to pick up the critical loads. In this presentation, a resilient and sustainable framework in modern distribution systems using advanced microgrids will be introduced. Particularly, to provide effective solutions against severe faults, such as those induced by natural disasters, a distribution system can be sectionalized into multiple microgrids to not only isolate the faults and prevent its further influence on the rest of the system but also restore the grid service of critical loads in a fast manner. When using inverter interfaced DERs, a flexible operation can be realized by dynamically implementing advanced microgrids in order to satisfy the real time source and load balance. A bi level system is developed to implement a holistic solution, where the central optimization engine at the upper level determines the boundaries of the microgrids in real time, while the lower level controller locating at each DER interface inverter is responsible for regulating local frequency and voltage and providing fault ride through function in each microgrid. In addition, when considering the stochastic output power of each DER, a region wise method is proposed to evaluate the system stability of each autonomous microgrid dynamically implemented via sectionalization. Meanwhile, coordinated control of both AC and DC microgrids is deployed to stabilize the operation of each autonomous microgrid.
High-dimensional additive modeling
Creators: name: Meier, Lukas
name: van de Geer, Sara
name: Bühlmann, Peter
Publisher: name: arXiv
Year: 2008
Subjects: subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences
subject: 62G08, 62F12 (Primary), 62J07 (Secondary)

description: We propose a new sparsity-smoothness penalty for high-dimensional generalized additive models. The combination of sparsity and smoothness is crucial for mathematical theory as well as performance for finite-sample data. We present a computationally efficient algorithm, with provable numerical convergence properties, for optimizing the penalized likelihood. Furthermore, we provide oracle results which yield asymptotic optimality of our estimator for high dimensional but sparse additive models. Finally, an adaptive version of our sparsity-smoothness penalized approach yields large additional performance gains.
description: Published in at http://dx.doi.org/10.1214/09-AOS692 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Three-Phase LLC Resonant Converters for Battery Chargers-Slides
Creators: Abbas Arshadi & Martin Ordonez
Publisher: name: IEEE
Year: 2020

PELS Webinar Slides
Abstract: Three-phase LLC resonant converters can handle very high power levels beyond the capabilities of half-bridge and full-bridge LLC topologies. Among other characteristics, three-phase LLC structures reduce output current ripple (small output filter), enable parallel power processing (low peak current), and provide good thermal distribution. However, the design of three-phase LLC converters for fast Electric Vehicle (EV) chargers can be challenging. This talk explores some of the requirements for fast EV battery chargers (voltage regulation, current balancing, etc.) and proposes tentative solutions to overcome them.
Catocala benjamini subsp. ute Peacock & Wagner 2009
Creators: name: Hawks, David
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Lepidoptera
Noctuidae
Catocala
Catocala benjamini
Catocala benjamini ute peacock & wagner

description: Catocala benjamini ute Peacock & Wagner Fig. 10 Type material. Catocala benjamini ute: holotype ♁ [PMNH, examined]. Type locality: USA, Utah, Grand Co[unty], Arches National Park, Balanced Rock Area, 1610 m. Diagnosis. Similar to other subspecies, although slightly larger in size and with an orange-brown ground color, and yellow orange usually infusing other aspects of the maculation; underside with reduced black scaling in both basal and adterminal areas; adterminal not as checkered as in other subspecies. Distribution and biology. Known only from Grand and San Juan counties in southeastern Utah, in the most northeastern part of the species’ overall range. Adults have been taken in early June. Th e immature stages are unknown. Peacock and Wagner (2009) indicate Quercus × pauciloba Rydb. (= Q. undulata Torr.; a hybrid from Q. gambelii Nutt. and Q. turbinella) is the most prevalent and sometimes only oak species at the known collecting localities; they report the absence of C. benjamini ute from nearby stands of Q. gambelii.
description: Published as part of Hawks, David, 2010, Review of the Catocala delilah species complex (Lepidoptera, Erebidae), pp. 13-35 in ZooKeys 39 (39) on page 24, DOI: 10.3897/zookeys.39.439, http://zenodo.org/record/576631
description: {"references": ["Peacock JA, Wagner DL (2009) Catocala benjamini ute n. ssp. From southeastern Utah. Journal of Th e Lepidopterists' Society 63: 89 - 92."]}
Smart Battery Energy Management and Health Conscious Fast Charging for Future Transport-Slides
Creators: Sheldon Williamson
Publisher: name: IEEE
Year: 2020

PELS Webinar Slides
Abstract: It has become imperative to find a solution to manage energy production and usage accurately, especially within the context of future electric energy storage for aerial vehicles and autonomous e-transportation systems. Enhancing the life of Lithium-ion (Li-ion) battery packs has been the topic of much interest. In this framework, the role of on-board cell voltage balancing of Li-ion batteries will be highlighted in this talk. This is a very important topic in the context of battery energy storage cost and life/state-of-charge, SOC/state-of-health, SOH monitoring. Li-ion batteries, although popularly proposed for electric transport, have been highly uneconomic for energy storage, overshooting cost requirements by a large margin.This talk will also introduce a first-of-its-kind closed-loop cell charge (voltage) balancing and extreme fast charging technique. The technique uses instantaneous cell voltage and/or temperature rise (?T) as a control parameter. Existing charging techniques for Li-ion batteries use a largely open-loop approach, where the charge profile is pre-decided, based on apriori knowledge of cell parameters.  There is a need for closed-loop charging techniques that use instantaneous cell voltage and/or temperature to modulate the charging current magnitude. This seminar addresses this gap by proposing for the first time ever a constant-temperature constant-voltage (CT-CV) charging technique, considering cell temperature as a key degradation metric. This talk will also establish the benefits of the proposed CT-CV charging at cell level and increases the possibility of extending it to the pack level by integrating it with battery management systems.
title: Front Matter, Table of Contents, Preface, Conference Organization
Creators: name: Gørtz, Inge Li
name: Weimann, Oren
Publisher: name: Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Year: 2020
Subjects: subject: Front Matter
subject: Table of Contents
subject: Preface
subject: Conference Organization
subject: Theory of computation → Design and analysis of algorithms
subject: Theory of computation → Pattern matching
subject: Mathematics of computing → Discrete mathematics
subject: Mathematics of computing → Information theory
subject: Mathematics of computing → Combinatoric problems
subject: Information systems → Information retrieval
subject: Applied computing → Computational biology

description: Front Matter, Table of Contents, Preface, Conference Organization
description: LIPIcs, Vol. 161, 31st Annual Symposium on Combinatorial Pattern Matching (CPM 2020), pages 0:i-0:xvi
Bond-selective interferometric scattering microscopy
Creators: name: Yurdakul, Celalettin
name: Zong, Haonan
name: Bai, Yeran
name: Cheng, Ji-Xin
name: Unlu, M. Selim
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optics (physics.optics)
subject: Applied Physics (physics.app-ph)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Physical sciences

description: Interferometric scattering microscopy has been a very promising technology for highly sensitive label-free imaging of a broad spectrum of biological nanoparticles from proteins to viruses in a high-throughput manner. Although it can reveal the specimen's size and shape information, the chemical composition is inaccessible in interferometric measurements. Infrared spectroscopic imaging provides chemical specificity based on inherent chemical bond vibrations of specimens but lacks the ability to image and resolve individual nanoparticles due to long infrared wavelengths. Here, we describe a bond-selective interferometric scattering microscope where the mid-infrared induced photothermal signal is detected by a visible beam in a wide-field common-path interferometry configuration. A thin film layered substrate is utilized to reduce the reflected light and provide a reference field for the interferometric detection of the weakly scattered field. A pulsed mid-IR laser is employed to modulate the interferometric signal. Subsequent demodulation via a virtual lock-in camera offers simultaneous chemical information about tens of micro- or nano-particles. The chemical contrast arises from a minute change in the particle's scattered field in consequence of the vibrational absorption at the target molecule. We characterize the system with sub-wavelength polymer beads and highlight biological applications by chemically imaging several microorganisms including Staphylococcus aureus, Escherichia coli, and Candida albicans. A theoretical framework is established to extend bond-selective interferometric scattering microscopy to a broad range of biological micro- and nano-particles.
Power-Based Droop Control in DC Microgrids Enabling Seamless Disconnection from Upstream-Slides
Creators: Guangyuan Liu
Publisher: name: IEEE
Year: 2020

PELS Webinar Slides
Abstract: Dc microgrids are regarded as an effective way to aggregate Distributed Energy Resources (DERs), including distributed generators and energy storage systems, through power electronic converters. Droop control is a representative control strategy for DER converters in dc microgrids, enabling automatic and balanced power sharing. However, with conventional droop control method, power contributions from DER converters cannot be actively regulated. Instead, they are determined by loads power, which limits the control flexibility.

This presentation will introduce a local power-based droop controller for DER converters in dc microgrids that are connected to upstream grids. This controller combines the advantages of droop control and power flow control. Specifically, in grid-connected mode, it works like a power regulator to achieve flexible power flow control, while, in islanded mode, it behaves like a conventional droop controller to guarantee prioritized power distribution. Importantly, the controller can seamlessly transfer from power flow control to droop control, without any need of islanding detection schemes or critical communication. The detailed structure, operation principle, and performance validation will be presented in this webinar
Current-fed Isolated Modular Multilevel DC-DC Converter (iM2DC) for MVDC Applications Slides
Creators: Hui Li
Publisher: name: IEEE
Year: 2019

PELS Webinar Slides
Abstract- Isolated modular multilevel dc-dc converters (iM2DCs) have gained increased applications for MVDC systems including DC solid state transformers (SST) and battery energy storage systems (BESS). Compared to the voltage-fed counterparts, the current-fed iM2DCs have unique advantages due to their superior current control and fault performance.  This presentation will introduce different modulation methods of current-fed iM2DCs and the corresponding dynamic models as well as control system development. The advantages and disadvantages of each modulation method will be illustrated and compared.
Bio- Dr. Hui Li received her Ph.D. degree from the University of Tennessee, Knoxville, TN, USA, in 2000. From 1999 to 2000, she worked at Power Electronics and Electric Machinery Research Center of Oak Ridge National Laboratory. Currently she is a professor of Electrical and Computer Engineering Department, FAMU-FSU College of Engineering, USA. She leads power electronics research at Center for Advanced Power Systems (CAPS), Florida State University since 2002. Her research interests include dual-active-bridge converters, multilevel inverters, and PV inverters applying WBG devices. She has led a number of projects in the past to develop DC solid state transformers and WBG PV converters.  She has published over 100 high quality papers and the recipient of NSF Career Award (2007), IEEE PELS Transaction Paper Award (2014), and IEEE IAS Industrial Power Converter Committee Prize Paper award (2014).  She is an associate editor of IEEE Transaction on Power Electronics and IEEE Journal of Emerging and Selected Topics in Power Electronics. She is the elected member at large of Administrative Committee of IEEE Power Electronics Society from 2011-2013, 2015-2017, 2018-2020 and one of Distinguished Lecturers of Class 2018-2019. She is a Fellow of the IEEE
Introduction to ITRD - the Technology Roadmap of Power Electronics for DERs-Slides
Creators: Liuchen Chang
Publisher: name: IEEE
Year: 2020

PELS Webinar Slides
Abstract: Distributed energy resources (DERs) are rapidly growing in the global electricity market, while power electronics technologies enable additional functionalities and value-added services based on DERs. The Power Electronics Society has launched the project to develop the IEEE International Technology Roadmap of Power Electronics for Distributed Energy Resources (ITRD). The mandates of ITRD are to develop technology roadmap documents and associated publications through projecting the long-term technological developments and applications of power electronics for DERs, and to identify opportunities of new standards. ITRD intends to provide reference and guidance to stakeholders in power electronics for DERs, serving academia, industry, national labs, and research organizations.

Dr. Liuchen Chang will introduce ITRD in this webinar. He will provide an overview of global DER market growth; evolution of DER interconnection standards; ITRD organizational structure and expected outcomes; ITRD working groups and their scopes; and the contents of the first ITRD white paper. The six working groups of ITRD include: Integrated Power Components and Subsystems; Power Conversion for DERs; Integration and Control of DERs; Security, Protection and Resilience for DERs; MV and HV Technologies for DERs; Testing and Validation. Dr. Chang will present a review of the power system support functions from renewable DER inverters, including voltage regulation by active/reactive power control, frequency regulation by active power control, voltage ride-through, and frequency ride-through.
Catocala benjamini subsp. jumpi Hawks 2010, ssp. n.
Creators: name: Hawks, David
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Lepidoptera
Noctuidae
Catocala
Catocala benjamini
Catocala benjamini jumpi hawks

description: Catocala benjamini jumpi Hawks, ssp. n. urn:lsid:zoobank.org:act: EA01B04C-27EE-4604-83C5-7AF5696A3A6F Figs 11, 12 Type material. Holotype ♁ (Fig. 11, PMNH specimen #ENT 721047; FW length 21 mm), allotype ♀ (Fig. 12, PMNH specimen #ENT 721048; FW length 23 mm): Kofa Queen Canyon, 900 m, Kofa Mountains, Yuma County, Arizona, 27 May 1989, leg. D. C. Hawks. Paratypes (14 ♁ 16 ♀): 1 ♁ 6 ♀ from type locality, 29 May 1981, P.M. Jump; 13 ♁ 10 ♀ from type locality, 27 May 1989, D.C. Hawks. Th e remainder are from Palm Canyon, Kofa Mountains (6 ♁ l ♀, leg. G. Butler & D. Tuttle, 29 May 1955; 1 ♁ l ♀, leg. D. C. Hawks, 3 June 1985). Holotype and allotype deposited at PMNH, paratypes deposited at LACM and other USA museums as well as in private collections. Diagnosis. C. benjamini jumpi differs from other C. benjamini subspecies in having pale dusky-yellow hindwing bands; forewings distinctly narrower and more point- ed; lines less distinct; ventral surface yellow areas paler; black hindwing bands tend to be wider; inner band, outer band, and anal spot sometimes fused. Description. Forewing: narrow and pointed; dorsal surface with black, darkbrown, tan, and beige scales, few scales iridescent bluish or purplish; antemedial line black, edges indistinct; reniform black, subreniform usually beige, variable in size; apical yellowish area suffused with black; fringes gray, checkered with black. Hindwing: dorsal surface with pale-brown scales suffusing much of basal area; medial band dull pale yellowish; fringe yellowish tan with black checkering; bands black; ventral surface pale dusky yellow; fringe pale yellowish beige checkered with black; inner band usually only slightly narrower than on dorsal surface. Etymology. The subspecies is named in honor of Peter M. Jump, who introduced the author to this unique population of C. benjamini, and who collected seven of the type specimens. Distribution and biology. Catocala benjamini jumpi is known only from the Kofa Mountains of southwestern Arizona. Th e Kofa Mountains and the nearby Castle Dome Mountains are separated from the nearest known suitable locality for C. benjamini by about 140 km. Th e oaks (Q. turbinella) occurring in these two mountain ranges are notably disjunct in the overall range of this oak. Adults have been collected only in late May and early June. Larvae likely feed exclusively on Quercus turbinella since this is the only oak occurring in the area.
description: Published as part of Hawks, David, 2010, Review of the Catocala delilah species complex (Lepidoptera, Erebidae), pp. 13-35 in ZooKeys 39 (39) on pages 24-25, DOI: 10.3897/zookeys.39.439, http://zenodo.org/record/576631
Magnetic fields in the accretion disks for various inner boundary conditions
Creators: name: Boneva, Daniela V.
name: Mikhailov, Evgeny A.
name: Pashentseva, Maria V.
name: Sokoloff, Dmitriy D.
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The magnetic fields of accretion disks play an important role in studying their evolution. We may assume that its generation is connected to the dynamo mechanism, which is similar with that in the galactic disks. Here, we propose a model of the magnetic field of the accretion disk that uses the same approaches that have been used for galaxies. It is necessary to obtain the field, which is expected to be less than the equipartition value, and without destroying the disk. To do so, it is necessary to formulate the basic properties of the ionized medium and to estimate the parameters governing the dynamo. We used the no-z approximation that has been developed for thin disks. We also take different boundary conditions that can change the value of the field significantly. We show that the magnetic field strictly depends on the boundary conditions. Taking zero conditions and the fixed magnetic field condition on the inner boundary, which are connected to the physical properties of the accretion disk, we can avoid solutions that are greater than the equipartition field.
description: 9 pages, 9 figures, accepted for publication in Astronomy & Astrophysics
Modular Multilevel Converter (MMC) for Traction Applications Slides
Creators: Luiz Henrique Barreto and Dalton A. Honorio
Publisher: name: IEEE
Year: 2017

PELS Webinar Slides
Since its initial conception, the transformer has been used in the most diverse applications where insulation and adaptation of voltage levels are demanded. In fact, this device is widely employed either directly or indirectly in all electric engineering fields due its simple design for distinct power and voltage conversion levels. More specifically, the power transformer ensures the aforementioned characteristics in power systems applications, such as: ac power energy transmission and distribution, as well as, medium voltage machine drives. However, such applications are typically based on a bulky low frequency device called Line Frequency Transformer (LFT).

Moreover, many applications normally use oil inside the LFTs for cooling and insulation purposes, what has direct impact on weight and volume and implies serious environmental issues. Other drawback lies in the low efficiency of LFTs, since they are typically designed with high current densities (as less amount of copper is required) and operate at heavy load conditions that may result in operation with efficiency of 90 percent. In order to overcome such bottlenecks, many recent studies have tried to replace the conventional LFT for a power converter using a Medium Frequency Transformer (MFT) with operating frequency around thousands of hertz, thus reducing intrinsic size and the weight of magnetics.

Such reduction is a must in medium voltage machine drives, more particularly in electric railway application, since a more compact propulsion system is a requirement, resulting in the improvement of the transformer efficiency and reduction of the requested power with the same cargo capability. This advantage is specially desired in Electric Multiple Units (EMU) where the propulsion system is distributed among the locomotive cars.

Besides the voltage and weight reduction, the approach using MFTs must ensure harmonic mitigations, power factor correction, fault suppressions, among other functionalities.

This talk will present several SST topologies. Since all configurations are supposed to deal with high voltages levels due the innate SST propose, designers must choose the technology that best fits in their applications, considering the own particular characteristics.
Fundamental Theories of Wireless Power Transfer Slides
Creators: Chun T. Rim
Publisher: name: IEEE
Year: 2018

PELS Webinar Slides
Rapid expanding technologies of wireless power transfer (WPT) to mobile devices and electric vehicles (EVs) make electric charging more convenient, safe, and automatic. WPT business and industries are growing fast, and more people are getting involved in this area. Innovation on WPT is highly sought in this area, however, no substantial progress in technology is possible without thorough and philosophical understanding of WPT. It is very often ignored and underestimated by engineers and practitioners, but theory is the basis of great innovation. In this webinar, an overview of WPT and its fundamental principles are introduced first. Several theories on inductive power transfer (IPT), mostly invented by Prof. RIM, are explained, including the coupled coil models, gyrator circuit models, magnetic mirror models, active electromagnetic force (EMF) cancel models, and general unified dynamic phasor models. A few application examples of IPT for dynamic and static EV charging and mobile devices are shortly given. This webinar is based on two new books by Prof. RIM, Phasor Power Electronics, Springer, 2016, and Wireless Power Transfer for Electric Vehicles and Mobile Devices, Wiley, 2017.
Control and Estimation Techniques for the Safe Operation of Critical DC Microgrids-Slides
Creators: Luis Herrera
Publisher: name: IEEE
Year: 2021

PELS Webinar Slides
Abstract: DC microgrids are currently being employed in a wide range of applications, ranging from the transportation industry to high voltage dc systems. Nevertheless, there are still several challenges facing dc microgrids compromising their resiliency and safety. As most loads are nowadays interconnected through power converters, the stability of the network can be affected due to its behavior as a Nonlinear Constant Power Load (CPL). In addition, the constant dc voltage available has the potential to create continuous high impedance series arc faults, which are difficult to detect due to its low fault current. In this webinar, an overview of recent nonlinear control strategies and stability analysis of dc networks with CPLs will be presented. In addition, parameter estimation methods (e.g. Kalman filter, recursive least squares) will be presented for the accurate detection and localization of dc series arc faults.
Miniaturizing Energy Interfaces by Intelligent Control Slides
Creators: Mor Peretz
Publisher: name: IEEE
Year: 2018

PELS Webinar Slides
The rapid growth of portable and mobile electronics continuously tightens the specifications and adds restrictions on the power delivery. This is done to assure compact, light, energy efficient, and economical power sources. The power processors of modern electronics are required to be invisible and still answer all requirements of a high performance IC. In the worldwide trend of integration, digital design is predominant featuring several advantages such as design convenience, flexibility, scalability, and most of all, performance improvement. This is achieved by advanced hybrid and nonlinear control methods, such as boundary, sliding mode and other variations of large signal controllers that improve the dynamic performance and, as a result drastically reduce the overall volume of the SMPS. To facilitate lean digital hardware realization on one hand, and eliminate the dependence of the controller performance on the system variations on the other hand, state based or decision making based controllers have evolved along with systematic representation of the control laws on the state space. The main limitation for the majority of these controllers is that their stability cannot be directly guaranteed using the known techniques available in the literature, since an analytical formulation of the control law is not immediate.

Implications of the control method on the resultant response may vary from one converter configuration to another. For example, with direct energy transfer converters, e.g., buck or forward, the time optimal control produces the fastest possible dynamic response to load transients with the minimum possible output voltage deviation. However, when applying time optimal control on indirect energy transfer converters, e.g., boost or flyback, the fast dynamic response trades with the output voltage deviation and peak inductor current, increasing the sizing requirements from both the output capacitor and the inductor. On the other hand, minimum output voltage deviation for boost type converters results in prolong transient time, infinite in the ideal case.

This Webinar is devoted to raise awareness to the positive implications of intelligent hybrid controllers on power processing and conversion. It starts with a review from a physical perspective of state space representation for switching converters and puts in context the properties of the state trajectories and description of controllers. Then, a practical 5 step tool to examine large-signal stability and performance evaluation of switch mode converters is introduced. Finally, several controller variations are surveyed, compared and quantified.

Practicality as well as feasibility of realization of the controllers is a key issue of this Webinar. Therefore, every step is demonstrated on both simulation and experimental platforms, along with detailed hardware information.
Inferring the instability of a dynamical system from the skill of data assimilation exercises
Creators: name: Chen, Yumeng
name: Carrassi, Alberto
name: Lucarini, Valerio
Publisher: name: arXiv
Year: 2021
Subjects: subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Chaotic Dynamics (nlin.CD)
subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: Data assimilation (DA) aims at optimally merging observational data and model outputs to create a coherent statistical and dynamical picture of the system under investigation. Indeed, DA aims at minimizing the effect of observational and model error, and at distilling the correct ingredients of its dynamics. DA is of critical importance for the analysis of systems featuring sensitive dependence on the initial conditions, as chaos wins over any finitely accurate knowledge of the state of the system, even in absence of model error. Clearly, the skill of DA is guided by the properties of dynamical system under investigation, as merging optimally observational data and model outputs is harder when strong instabilities are present. In this paper we reverse the usual angle on the problem and show that it is indeed possible to use the skill of DA to infer some basic properties of the tangent space of the system, which may be hard to compute in very high-dimensional systems. Here, we focus our attention on the first Lyapunov exponent and the Kolmogorov-Sinai entropy, and perform numerical experiments on the Vissio-Lucarini 2020 model, a recently proposed generalisation of the Lorenz 1996 model that is able to describe in a simple yet meaningful way the interplay between dynamical and thermodynamical variables.
description: 23 pages, 10 figures
Power Electronics Facing Technical Challenges of a New Era of Electric Energy Systems-Slides
Creators: Jinjun Liu
Publisher: name: IEEE
Year: 2020

PELS Webinar Slides
Abstract: Electric energy systems entering into a new era have been experiencing many changes towards the future, among which turning into more electronic, i.e. integrating more and more electronic power converters, and incorporating more and more distributed generations are the two major ones. The technical challenges that power electronics will be facing accordingly are then identified one by one.  The major issues caused by becoming more electronic and more distributed are discussed. The issues that are to some extent in dispute among different technical people with different backgrounds are also elaborated, including the concern about system inertia reduction, the worry about lower transient over-current tolerance, and the new system framework and specifications that need to be set up. Proposed power electronics solutions supported by most recent research results are illustrated in more detail in the end, with examples more concentrated in the area of communication-free coordinative control of paralleled interfacing inverters for distributed energy sources.
Fluorosulfates of the noble metals, and their use in novel superacid systems
Creators: name: Lee, Keith Cheuk-Lap
Publisher: name: University of British Columbia
Year: 2010

description: This study was initiated by the search for novel superacid systems based on HSO₃F, the strongest simple protonic acid. Therefore, the synthesis of binary metal fluorosulfates, M(SO₃F)n, was investigated, with special emphasis on compounds where M is in a medium or high oxidation state and formally coordinatively unsaturated, i.e., n = 3,4 or 5. Preferably, the resulting fluoro-sulfate would also display a sufficiently high thermal stability with respect to dissociations giving rise to SO₃ or S₂O₅F₂, and reasonable solubility in HSO₃F. In order to obtain suitable binary fluorosulfates, a new, generally applicable synthetic method was developed, involving the oxidation of a metal with S₂O₆F₂. In presence of HSO₃F: M+ n/2 S₂O₆F₂ -- HSO₃F M(SO₃F)[sub= n], where M is primarily a 4d or 5d transition metal, in particular, palladium, platinum, gold and iridium. This fluorosulfonation mixture combines the strong oxidizing ability of S₂O₆F₂ with the good solvating property of HSO₃F towards ionic solutes. The ability of these binary fluorosulfates to act as fluorosulfate ion acceptors was established by the synthesis of anionic complexes of the type [M(SO₃F)[sub= n+m][sup= m-], where m = 1,2. Both Au(SO₃F)₃ and Pt(SO₃F)₄ were found to act as ansolvo-acids in H SO₃F by the removal of fluorosulfate ions from the solvent ionization equilibrium: 2H SO₃F > H₂SO₃F⁺ + SO₃F⁻, to form [Au(SO₃F)₄]⁻ or [Pt(SO₃F)₆]²⁻ . Results from conductivity measurements indicate the resulting superacids have acid strengths comparable to that of the HSO₃F-SbF₅-SO₃ system and definitely superior to the HSO₃F –SbF₅ system. In both cases, the variety of ternary fluorosulfates synthesized included unusual cations such as Br₃⁺ and Br₅⁺. In the case of platinum, evidence for poly-nuclear oligomeric anions of the type of [Pt(SO₃F)₅][sub= n][sup= n-] were obtained; similar observations were also made in the tin system. The oxidation of palladium yielded Pd(SO₃F)₂ and a mixed valency compound, Pd(II)[Pd(IV)(SO₃F)₆], both containing Pd(II) in a rather uncommon octahedral coordination sphere and a ³A₂₉ electronic ground state. These magnetically dilute compounds allowed meaningful magnetic results and ligand field parameters to be interpreted. Both Ir(S0₃F)₃ and Ir(SO₃F)₃ could be synthesized, along with some tenary fluorosulfate complexes. Some preliminary results were also obtained on the fluorosulfates of germanium, molybdenum, niobium and tantalum.
An accreting white dwarf displaying fast transitional mode switching
Creators: name: Scaringi, S.
name: de Martino, D.
name: Buckley, D. H.
name: Groot, P. J.
name: Knigge, C.
name: Fratta, M.
name: Ilkiewicz, K.
name: Littlefield, C.
name: Papitto, A.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Accreting white dwarfs are often found in close binary systems with orbital periods ranging from tens of minutes to several hours. In most cases, the accretion process is relatively steady, with significant modulations only occurring on time-scales of ~days or longer. Here, we report the discovery of abrupt drops in the optical luminosity of the accreting white dwarf binary system TW Pictoris by factors up to 3.5 on time-scales as short as 30 minutes. The optical light curve of this binary system obtained by the Transiting Exoplanet Survey Satellite (TESS) clearly displays fast switches between two distinct intensity modes that likely track the changing mass accretion rate onto the white dwarf. In the low mode, the system also displays magnetically-gated accretion bursts, which implies that a weak magnetic field of the white dwarf truncates the inner disk at the co-rotation radius in this mode. The properties of the mode switching observed in TW Pictoris appear analogous to those observed in transitional millisecond pulsars, where similar transitions occur, although on timescales of ~tens of seconds. Our discovery establishes a previously unrecognised phenomenon in accreting white dwarfs and suggests a tight link to the physics governing magnetic accretion onto neutron stars.
description: Submitted on 17 June 2021. Accepted for publication in Nature Astronomy on 18 August 2021
Emerging (Ultra-) Wide Bandgap Power Devices on the Horizon-Slides
Creators: Yuhao Zhang
Publisher: name: IEEE
Year: 2020

PELS Webinar Slides
Abstract: In the last decade, the power electronics landscape has been reshaped with the production and application of power devices based on wide-bandgap (WBG) semiconductors, such as gallium nitride (GaN) and silicon carbide (SiC). Besides advancing the performance of traditional power systems, WBG devices have also enabled many emerging applications that are beyond the realm of silicon (Si) as well as changed the manufacturing paradigm of power electronics.
This talk will present the development of next-generation WBG and ultra-wide-bandgap (UWBG) power devices as well as the switching-based ruggedness study of WBG devices. We recently developed a group of novel 1.2 kV GaN devices based on the vertical architecture, which have shown great promise to expand the application space of GaN into the medium-voltage realm. Besides GaN, our work on an emerging UWBG material, gallium oxide, has suggested new enabling capabilities of UWBG power devices for high-temperature applications. Finally, we will present our robustness study of WBG power devices, with an emphasis on new degradation mechanisms and device physics unveiled from the avalanche tests of GaN HEMTs and hard-switching-based accelerated tests of SiC MOSFETs.
Current sharing technologies for LLC resonant converters Slides
Creators: Yan-Fei Liu
Publisher: name: IEEE
Year: 2017

PELS Webinar Slides
LLC resonant converters become more popular due to its desirable features, such as zero voltage switching, high switching frequency operation, possible integration of the resonant inductor into the transformer. However, its output voltage is controlled by switching frequency, or more accurately, its voltage is controlled by the ratio of the switching frequency and the resonant frequency. When two or more LLC converters are connected in parallel, they cannot achieve current sharing because of the tolerance of the resonant components. In this webinar, two technologies will be introduced to achieve current sharing of the LLC resonant converters. One is Switch-Controlled-Capacitor (SCC) technology and the other sharing inductor technology. SCC technology uses a low voltage rating MOSFET (less than 100V) to fine tune the equivalent resonant frequency to compensate the tolerance of the resonant components. The shared inductor technology does not add any additional components. It connects the two resonant inductors in parallel to achieve current sharing. The operation of these two schemes will be introduced in details during the Webinar. The key equations will also be provided. The webinar is intended for engineers and students intermediate technical level of resonant converters, switching converters.
Activation of Strong C–H and C–O Bonds for Transition Metal-Catalyzed Cross-Coupling
Creators: name: Freure, Garrett
Publisher: name: Université d'Ottawa / University of Ottawa
Year: 2021
Subjects: Palladium
Nickel
Cross-coupling
Superbase
C(sp3)-H activation
Organolithium cross-coupling
Strong C-O activation
Catalysis

description: Transition metal-catalyzed cross-coupling is one of the most dominant fields of modern synthetic organic chemistry. Research is forever ongoing, in which there is constant expansion of the scope of nucleophilic- and electrophilic- coupling partners, and consequently the types of products that can be formed. More specifically, strong bond activation in cross-coupling is an emerging field that can enable late-stage functionalization; by activating inert functional groups that were untouched in earlier synthetic steps, they can be taken advantage of for further derivatization. This thesis will focus on the use of aggressive reagents in the activation of strong C–H and C–O bonds for their use in transition metal-catalyzed cross-coupling. Chapter 1 will involve the use of organometallic superbases in the palladium-catalyzed cross-coupling of sp3-hybridized carbon-centered nucleophiles. Deprotonation and subsequent electrophilic quench can be considered the most classical form of C–H activation. While modern approaches frequently focus on radical mechanisms or directing groups as modes of C–H activation, stoichiometric metalation has been largely overlooked in the context of cross-coupling. By using aggressive organometallic superbases to deprotonate very weakly acidic C–H bonds, the resultant organometallic species can be taken advantage of as cross-coupling nucleophiles. This chapter will investigate the coupling of organolithiums and organozincs generated in situ in the C(sp3)–H arylation of an array of unactivated substrate classes. Chapter 2 will briefly investigate the use of aggressive alkyl metallic additives in the C–O activation of silyl enol ethers as Suzuki-Corriu cross-coupling electrophiles. Converting ketones to substituted olefins using cross-coupling is a common approach in medicinal chemistry for the synthesis of complex bioactive products. While reliable, this chemistry is generally very inefficient due to multi-step synthesis and the instability of activated intermediates. In contrast, applying modern nickel-catalyzed C–O activation to robust silyl enol ethers made in situ could alleviate these limitations. Using triethylborane as an additive, a nickel-catalyzed Suzuki-Corriu cross-coupling of silyl enol ethers was discovered. While ultimately unsuccessful, attempts were also made to optimize, explore the scope, and elucidate the mechanism of this reaction.
High Efficiency DC DC Converters with a New Coupled-Inductor-Rectifier Structures-Slides
Creators: Jung-Kyu Han
Publisher: name: IEEE
Year: 2020

PELS Webinar Slides
Abstract: Among the various DC-DC converters, PWM half bridge-full bridge converters are widely used in various applications due to many advantages. However, although they have high performances, many problems are remained to be solved. To solve these problems, a new rectifier structures adopting a coupled inductor are proposed. By using the rectifier structure, the proposed half bridge-full bridge converters overcome limitations of the conventional converters while it keeps the advantages of them. The proposed coupled-inductor-rectifier (CIR) has three major advantages. First, it has small voltage stress in rectifier diodes which enables a use of small voltage stress diodes having low VF. Second, two snubber circuits are eliminated compared with the FBR. It not only decreases cost and complexity of the converter, but it also increases efficiency. Lastly, combined with half-bridge and full-bridge inverters of primary side, the CIR solves the main problems of the conventional converters such as DC-offset current of the transformer and primary freewheeling current. In addition, since the proposed converters do not require any additional components, it can be easily applied to various applications.
Towards Sustainable and Reliable Automated Design of Power Electronic Systems-Slides
Creators: Ivana Kovacevic
Publisher: name: IEEE
Year: 2021

PELS Webinar Slides
Abstract: Wide Band Gap (WBG) power devices have the potential to provide a paradigm shift with respect to performance and energy efficiency compared to the mature silicon (Si) power devices.  The fast switching capabilities and the material properties of WBG power devices make the system design more challenging, with respect to system integration, fast voltage and current slopes triggering the effects of parasitic inductive and capacitive couplings, high electromagnetic interference emission, and thermal couplings. These new design aspects imply a reformulation of design procedures developed for Si-based power electronics, which is required for successfully adapting WBG power devices. Automated system design is foreseen as a future of power electronics enabling optimal design solutions at minimal costs by considering dominant multi-physics design aspects.

The state-of-the-art multi-physics modeling approaches become computationally powerful, however not yet good enough for being fully integrated in an automated design process. The trade-off between accuracy and computational time has been an important challenge preventing virtual prototyping based on multi-physics modeling to further reduce the needs for extensive hardware prototyping. This webinar will provide an overview of the state-of-the-art multiphysics modeling approaches well established in power electronics, pointing out to the tasks still to be solved for developing sustainable and reliable automated design of power electronic systems.
Pore Wetting in Desalination of Brine Using Membrane Distillation Process
Creators: name: Chamani, Hooman
Publisher: name: Université d'Ottawa / University of Ottawa
Year: 2021
Subjects: Pore Wetting
Membrane Distillation
Desalination
Modeling

description: It goes without saying that water scarcity is a widespread and increasingly pressing global challenge. One of the methods which can mitigate water shortage is to increase freshwater production via desalination of saline waters. Seawater and saline aquifer sources represent 97.5% of all water on Earth. Hence, treating even a small portion of saline water could significantly reduce water shortage. Although reverse osmosis is one of the state-of-the-art pressure-driven membrane desalination technologies, it is incapable of desalinating high-salinity streams due to the very high osmotic pressure to overcome. Membrane distillation (MD) is one of the emerging methods, which has attracted much attention for desalinating highly saline brines. MD is a thermally driven process in which only vapor molecules pass through the pores of a microporous hydrophobic membrane. This process, however, has not been fully commercialized due to a number of challenges, including “pore wetting”. Pore wetting refers to the presence of liquid, instead of just water vapor, inside the membrane pores, which may cause a decrease in MD flux and/or deterioration of distillate quality. Herein, a comprehensive review on pore wetting is presented, and then this phenomenon is investigated from four aspects. In the first phase of this project, a theoretical model is presented according to which the pore size distribution of membrane, a parameter affecting pore wetting risk, is estimated by employing only a few experimental data points in accordance with the wet/dry method, reducing the number of data required to be recorded largely. In the next phase, an equation is presented for the estimation of liquid entry pressure (LEP), a membrane parameter closely related to pore wetting, using computational fluid dynamics (CFD) tools and genetic programming (GP) as an intelligent technique. This equation can estimate LEP in closer agreement to experimental values in comparison to the Young-Laplace equation. In the third phase, movement of liquid-gas interface inside the membrane pore is tracked using a well-founded model, and consequently, the pressure and velocity at the interface and the required time for replacement are studied. Finally, in the last phase, a model is developed for pore wetting in vacuum MD, considering heat and mass balances at the vapor-liquid interface. This model assumes that heat only enters the pore inlet and is removed due to liquid vaporization at the vapor-liquid interface, with heat transfer through the pore wall neglected. This model shows that partial pore wetting is possible since the vapor-liquid interface might remain within the pore at the steady-state condition. Further, this model can predict the decrease in temperature from the pore inlet to the vapor-liquid interface, a phenomenon that has been reported in the literature without any proof.
Electron Spin Resonance of the itinerant ferromagnets LaCrGe3, CeCrGe3 and PrCrGe3
Creators: name: Sichelschmidt, Jörg
name: Gruner, Thomas
name: Das, Debarchan
name: Hossain, Zakir
Publisher: name: arXiv
Year: 2021
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We report Electron Spin Resonance of the itinerant ferromagnets LaCrGe3, CeCrGe3, and PrCrGe3. These compounds show well defined and very similar spectra of itinerant Cr 3d spins in the paramagnetic temperature region. Upon cooling and crossing the Cr-ferromagnetic ordering (below around 90 K) strong spectral structures start to dominate the resonance spectra in a quite different manner in the three compounds. In the Ce- and Pr-compounds the resonance is only visible in the paramagnetic region whereas in the La-compound the resonance can be followed far below the ferromagnetic ordering temperature. This behavior will be discussed in terms of the specific interplay between the 4f and 3d magnetism which appears quite remarkable since CeCrGe3 displays heavy fermion behavior even in the magnetically ordered state.
description: 9 pages, 5 figures