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Open Access Publications from the University of California

Scholarly Works (18 results)

  • Thesis
  • Peer Reviewed
UC Irvine Electronic Theses and Dissertations (2016)

Voltage boosting is required in many energy conversion applications, ranging from front-end solar energy system to Medium-Voltage DC (MVDC)-grid system, and from headlamp ballast of automobile to fuel cell powered system. This dissertation is dedicated to the development of voltage boosting technology. New circuits were found both in switched capacitor converters and inductor-based power converters. The former has the potential of full integration while the latter has combined the merits of conventional magnetic components and switched capacitor stages, leading to a new hybrid converter category. These contributions are captured in two major parts respectively: The first part discusses the switched capacitor converters and new discovery in voltage boosting technology as well as modeling technique. The second part introduces a number of new topologies and extensions in hybrid boosting converters.

Part I

Switched Capacitor Converter (SCC) is a special branch of power electronics converters which is composed of capacitors and switches without the participation of inductors/transformers. It potentially has lower electromagnetic interference (EMI), lighter weight, lower cost, higher energy density, and the promise for full integration.

In this part, a family of "Two-switch Boosting Switched-capacitor Converters (TBSC)" is introduced, which distinguishes itself from the prior arts by its symmetrical interleaved operation, reduced output ripple, low yet even voltage stress on components, and systematic expandability. Along with the topologies, a modeling technique based on charge-balance transient-calculation is formulated, which provokes the converter regulation method through duty cycle and frequency adjustment. The design guideline for high efficient TBSC is provided and regulation under high power condition is explored.

In addition, an enhanced accurate modeling technique considering the output capacitor effect is developed for simple two-phase SC converters.

Part II

Built upon the momentum of the "Two-switch Boosting Switched-capacitor Converters (TBSC)" circuit structure, another family of Hybrid Boosting Converters (HBC) is developed, featuring wide regulation range, symmetrical configuration, low component voltage stress, small output voltage ripple, and expandable structure. It integrates the inductive switching cores of various functionalities and control strategies with Bipolar Voltage Multiplier (BVM), resulting in the new breed of hybrid converters: Hybrid Boosting Converters (HBC). The proposed HBC family includes the basic HBC, symmetrical HBC, Isolated HBC, and tapped inductor HBC, all of which are analyzed in details and design considerations are provided.

In addition, the 3D DC-DC converter concept for high power application, inverter configuration and DC micro-grid based on HBC converters are developed.

The proposed HBCs are applicable in many areas such HID lamp driver, X-ray system, ion pumps, front-end photovoltaic energy system, and energy storage systems.

    Cover page: The Art of Voltage Boosting Part I: Boosting Switched Capacitor Converter Part II: Hybrid Boosting Converters
    • Article
    • Peer Reviewed
    UC Santa Cruz Previously Published Works (2019)
      Cover page: Bottom-Up Approach for High Speed SRAM Word-line Buffer Insertion Optimization.
      • Article
      • Peer Reviewed
      UC Santa Cruz Previously Published Works (2019)
        Cover page: Bottom-Up Approach for High Speed SRAM Word-line Buffer Insertion Optimization
        • Article
        • Peer Reviewed
        LBL Publications (2017)
        Using deep inelastic scattering on a large nucleus as an example, we consider the transverse momentum broadening of partons in hard processes in the presence of medium. We find that one can factorize the vacuum radiation contribution and medium related PT broadening effects into the Sudakov factor and medium dependent distributions, respectively. Our derivations can be generalized to other hard processes, such as dijet productions, which can be used as a probe to measure the medium PT broadening effects in heavy ion collisions when Sudakov effects are not overwhelming.
          Cover page: Medium induced transverse momentum broadening in hard processes
          • Article
          • Peer Reviewed
          UC Santa Cruz Previously Published Works (2019)
            Cover page: Fast and Area-Efficient SRAM Word-Line Optimization
            • Article
            • Peer Reviewed
            LBL Publications (2016)
            We study the dijet azimuthal de-correlation in relativistic heavy ion collisions as an important probe of the transverse momentum broadening effects of a high energy jet traversing the quark–gluon plasma. We take into account both the soft gluon radiation in vacuum associated with the Sudakov logarithms and the jet PT-broadening effects in the QCD medium. We find that the Sudakov effects are dominant at the LHC, while the medium effects can play an important role at RHIC energies. This explains why the LHC experiments have not yet observed sizable PT-broadening effects in the measurement of dijet azimuthal correlations in heavy ion collisions. Future investigations at RHIC will provide a unique opportunity to study the PT-broadening effects and help to pin down the underlying mechanism for jet energy loss in a hot and dense medium.
              • Article
              • Peer Reviewed
              UC Santa Cruz Previously Published Works (2016)
                Cover page: OpenRAM: an open-source memory compiler
                • Article
                • Peer Reviewed
                UC Santa Cruz Previously Published Works (2020)
                  Cover page: Enabling Design Technology Co-Optimization of SRAMs through Open-Source SoftwareCreative Commons 'BY-SA' version 4.0 license
                  • Article
                  • Peer Reviewed
                  UC San Francisco Previously Published Works (2021)
                  Direct electrical stimulation, the transient 'lesional' method probing brain function, has been utilized in identifying the language cortex and preserving language function during epilepsy and neuro-oncological surgeries for about a century. However, comparison of functional maps of the language cortex across languages/continents based on cortical stimulation remains unclear. We conducted a retrospective multicentre study including four cohorts of direct electrical stimulation mapping from four centres across three continents, where three indigenous languages (English, French and Mandarin) are spoken. All subjects performed the two most common language tasks: number counting and picture naming during stimulation. All language sites were recorded and normalized to the same brain template. Next, Spearman's correlation analysis was performed to explore the consistency of the distributions of the language cortex across centres, a kernel density estimation to localize the peak coordinates, and a hierarchical cluster analysis was performed to detect the crucial epicenters. A total of 598 subjects with 917 speech arrest sites (complete interruption of ongoing counting) and 423 anomia sites (inability to name or misnaming) were included. Different centres presented highly consistent distribution patterns for speech arrest (Spearman's coefficient r ranged from 0.60 to 0.85, all pair-wise correlations P < 0.05), and similar patterns for anomia (Spearman's coefficient r ranged from 0.37 to 0.80). The combinational speech arrest map was divided into four clusters: cluster 1 mainly located in the ventral precentral gyrus and pars opercularis, which contained the peak of speech arrest in the ventral precentral gyrus; cluster 2 in the ventral and dorsal precentral gyrus; cluster 3 in the supplementary motor area; cluster 4 in the posterior superior temporal gyrus and supramarginal gyrus. The anomia map revealed two clusters: one was in the posterior part of the superior and middle temporal gyri, which peaked at the posterior superior temporal gyrus; and the other within the inferior frontal gyrus, peaked at the pars triangularis. This study constitutes the largest series to date of language maps generated from direct electrical stimulation mapping. The consistency of data provides evidence for common language networks across languages, in the context of both speech and naming circuit. Our results not only clinically offer an atlas for language mapping and protection, but also scientifically provide better insight into the functional organization of language networks.
                    Cover page: Functional maps of direct electrical stimulation-induced speech arrest and anomia: a multicentre retrospective study
                    • Article
                    • Peer Reviewed
                    LBL Publications (2017)
                    The SuFEx-based polycondensation between bisalkylsulfonyl fluorides (AA monomers) and bisphenol bis(t-butyldimethylsilyl) ethers (BB monomers) using [Ph3 P=N-PPh3 ]+ [HF2 ]- as the catalyst is described. The AA monomers were prepared via the highly reliable Michael addition of ethenesulfonyl fluoride and amines/anilines while the BB monomers were obtained from silylation of bisphenols by t-butyldimethylsilyl chloride. With these reactions, a remarkable diversity of monomeric building blocks was achieved by exploiting readily available amines, anilines, and bisphenols as starting materials. The SuFEx-based polysulfonate formation reaction exhibited excellent efficiency and functional group tolerance, producing polysulfonates with a variety of side chain functionalities in >99 % conversion within 10 min to 1 h. When bearing an orthogonal group on the side chain, the polysulfonates can be further functionalized via click-chemistry-based post-polymerization modification.
                      Cover page: SuFEx‐Based Polysulfonate Formation from Ethenesulfonyl Fluoride–Amine Adducts
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