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Open Access Publications from the University of California

Scholarly Works (1570 results)

  • Thesis
  • Peer Reviewed
UC San Diego Electronic Theses and Dissertations (2007)
    Cover page: Disordered electronic and magnetic systems - transition metal (Mn) and rare earth (Gd) doped amorphous group IV semiconductors (C, Si, Ge)
    • Thesis
    • Peer Reviewed
    UC San Diego Electronic Theses and Dissertations (2006)
    Estimation of models for both plant and disturbance dynamics is important in controller design applications which especially focus on the disturbance and vibration rejection. Several methods for low order model estimation on the basis of the closed-loop data exist in the literature, but fail to address the simultaneous estimation of low order models of both plant and disturbance dynamics. This dissertation contributes to the development of a new methodology to extend the results to low order disturbance model estimation, and apply these techniques to the control problems for disturbance rejection. In addition to the control relevant estimation problem, this dissertation also provides new tools for feedforward based disturbance rejection found in Active Noise Control (ANC) systems. We focus on the feedforward control algorithms that are one of the most popular methods to cancel low frequency sound where passive methods are ineffective. This dissertation shows that the feedforward filter design can also be seen as a model matching problem with the system model approximated on the basis of the expansion of orthonormal basis functions. Therefore, existing results on generalized FIR filters are exploited to provide feedforward compensation with the advantage of including the prior information of the system dynamics in the tapped delay line of the filter. It has the same linear parameter structure as FIR filter which is favorable for adaptation process. In the case that the acoustic coupling can not be neglected in the process of designing the feedforward filter, a dual-Youla parametrization is introduced and applied to estimate the possible perturbation of the feedforward filter and the robust stability of the closed loop system is enforced during the design of feedforward filter for active noise cancellation
      Cover page: Control relevant identification of plant and disturbance dynamics with application to noise and vibration control
      • Article
      Policy Briefs (2023)
        Cover page: How Slow Are Slow Streets? Countermeasure Effectiveness at Reducing Vehicle Speeds on Los Angeles Slow Streets
        • Thesis
        • Peer Reviewed
        UC San Diego Electronic Theses and Dissertations (2014)
        Previously, scientist studied metabolites of polymicrobial communities by direct chemical extraction or microbial isolation. While the old day method does not provide a lot of information from a polymicrobial community, in this master thesis, I have introduced and shown a novel method to investigate the metabolites and the metabolites distribution in three-dimensional space on a polymicrobial community by guidance of advanced technique of mass spectrometry such as MALDI-IMS & LC-MS. Specifically, I have developed a methodology to construct a three- dimensional metabolites map of a Peltigera sp. lichen to reveal the spatial metabolites distribution on lichen, hypothesis the possible function of a specific metabolites in the community and identify some of the specific metabolites. As a consequence of this new 3D metabolites map methodology, wide ranges of molecules were observed in this Peltigera sp. 3D model such as polypeptides, single amino acid, photosensitive molecules, polysaccharide and some lipid molecules. In addition, the 3D model clearly shows that the metabolites distribution inside Peltigera sp. lichen, and distributions of chlorophylls as well as a lipid from lichen fungi are correlated with previous reported literature. Some of these molecules are able to identify and derive its function in this biological system. These results demonstrated that the 3D metabolites map of Peltigera sp. lichen provides a means to direct visualize the spatial architecture of metabolites inside this polymicrobial community as well as study them from different angle, and hence useful for studying the metabolites and biological system of polymicrobial communities
          Cover page: The Molecular Architecture of Lichen Polymicrobial Community
          • Article
          Capstone Projects (2023)
          The Los Angeles Department of Transportation (LADOT) initiated the Slow Streets program to create opportunities for multimodal transportation and outdoor recreation during the Covid-19 pandemic. The program initially used low-cost barricades and signage to demarcate Slow Street segments before upgrading to six new traffic calming measures, or countermeasures, in Phase 2 that were designed to reduce speeds. This report evaluated their effectiveness through analyzing StreetLight speed data and employing a custom formula comparing speed changes on Slow Street segments to estimate each countermeasure’s speed-reducing effect. Nearly half of the segments experienced speed increases after countermeasure installation. Though it was difficult to attribute these speed increases to any reasons with certainty, we speculate that the countermeasures may not have caused great enough changes in street geometries to significantly alter driver behaviors and reduce speeds. Drivers may be using Slow Street segments to “cut through” traffic, and Slow Streets may not have been able to evade speed increases that have occurred on many streets during and after Los Angeles’ stay-at-home orders went into effect. Based on the results, LADOT should prioritize the installation of treatments located at or near intersections, which have shown to be most effective. LADOT should also reduce lane widths on entire street segments rather than at certain points along the street and consider alternative materials to work around current design restrictions. Finally, LADOT should perform a qualitative study of the effectiveness of the program and improve information access of the Slow Streets network by publishing interactive maps online.
            Cover page: Slow Streets! Your Streets? An Evaluation of Speed-Reducing Countermeasures on LA Slow Streets
            • Article
            LBL Publications (2011)
              Cover page: Closed-Form Formulas for Estimation of Kinetic Parameters in One- and Two-Compartment Models
              • Article
              • Peer Reviewed
              Lawrence Berkeley National Laboratory (2008)
                Cover page: X-ray absorption study of the electronic structure of Mn-doped amorphous Si
                • Article
                • Peer Reviewed
                Volume 4, Issue 1 (Spring 2024) (2024)
                This manuscript discusses how acupuncture has been incorporated into the twenty-first century US healthcare system. It traces the development of Chinese Medicine, and its uniquely localized variations in the US to date: Chinese Medicine in the US, Traditional Chinese Medicine, and American Chinese Medicine. I argue that Chinese Medicine has now entered a new stage, United States Chinese Medicine— where strictly, acupuncture’s definition in state regulation has affected its coverage under both private and federal health insurance to the detriment of patients and practitioners alike. The interaction of federal and state governments, regulatory boards, insurance companies, and acupuncture practitioners has created an unorganized framework across the country, effectively transforming it from being a unified “American” practice into an incongruous set of fifty. Through a lack of federal direction, separate state-specific acupuncture ecosystems emerge, in which practitioners follow available financial incentives to determine their state of choice. Through the non-consensus between governments, insurance providers, and practitioners concerning the purpose and practicality of acupuncture, insurance providers default to the biomedical healthcare paradigm’s standards to assign a monetary value to said component of alternative/complementary medicine. As a result, practitioners must not only be equipped with the skills of their medical profession, but also be prepared to identify their place in the medicolegal landscape, as to ascertain the profitability, legality, and direction of their business.
                  Cover page: The United States of Acupuncture: An Assessment of Medicolegal Designation and Insurance Coverage’s Impact on US Practitioners
                  • Article
                  LBL Publications (2004)

                  Many laser ablation applications such as laser drilling and micromachining generate cavity structures. The study of laser ablation inside a cavity is of both fundamental and practical significance. In this dissertation, cavities with different aspect ratios (depth/diameter) were fabricated in fused silica by laser micromachining. Pulsed laser ablation in the cavities was studied and compared with laser ablation on a flat surface. The formation of laser-induced plasmas in the cavities and the effects of the cavities on the ablation processes were investigated. The temperatures and electron number densities of the resulting laser-induced plasmas in the cavities were determined from spectroscopic measurements. Reflection and confinement effects by the cavity walls and plasma shielding were discussed to explain the increased temperature and electron number density with respect to increasing cavity aspect ratio. The temporal variations of the plasma temperature and electron number density inside the cavity decreased more rapidly than outside the cavity. The effect of laser energy on formation of a plasma inside a cavity was also investigated. Propagation of the shock wave generated during pulsed laser ablation in cavities was measured using laser shadowgraph imaging and compared with laser ablation on a flat surface. It is found that outside the cavity, after about 30 ns the radius of the expanding shock wave was proportional to t2/5, which corresponds to a spherical blast wave. The calculated pressures and temperatures of the shocked air outside of the cavities were higher than those obtained on the flat surface. Lasers with femtosecond pulse duration are receiving much attention for direct fabrication of microstructures due to their capabilities of high-precision ablation with minimal damage to the sample. We have also performed experimental studies of pulsed femtosecond laser ablation on the flat surface of silicon samples and compared results with pulsed nanosecond laser ablation at a ultraviolet wavelength (266 nm). Crater depth measurements indicated that ablation efficiency was enhanced for UV femtosecond laser pulses. The electron number densities and temperatures of femtosecond-pulse plasmas decreased faster than nanosecond-pulse plasmas due to different energy deposition mechanisms. Plasma expansion in both the perpendicular and the lateral directions were studied.

                    Cover page: Laser ablation of electronic materials including the effects of energy coupling and plasma interactions
                    • Article
                    Lawrence Berkeley National Laboratory (2010)
                      Cover page: Distinct local electronic structure and magnetism for Mn in amorphous Si and Ge
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