Design and Implementation of Internal Model Based Controllers for DC/ AC Power Converters

The aim of this thesis is to design and implement an advanced control system for a working three-phase DC to AC power converter. Compared to' the traditional PI controller used widely in industry, the new voltage controller can track the reference voltage with improved accuracy and efficiency in the presence of different kind of local loads, and also works well in the single phase voltage control. This voltage controller is combined with a power controller to yield a complete controller. An important aspect of this work is the hardware implementation of the whole system. Main parts ofthis thesis are: ???????? 1. Review ofH-infinity and repetitive control techniques and their applications in power converters. 2. Design of a new voltage controller to eliminate the DC component in the output voltages, and taking into account the practical issues such as the processing delay due to the digital signal processor (DSP) implementation. 3. Modelling and simulation of the converter system incorporating different control techniques and with different kinds of loads. 4. Hardware implementation and the two-processor controller. The parallel communication between the DSPs. 5. The main problems encountered in???????????????????? hardware implementation and programming. The software used to initialize DSPs, implement the discretetime voltage controller and other functions such ~ generations of space vector pulse width modulation (SVPWM) signals, circuit protections, analog to digital (AD) cOl)versions, data transmission, etc. 6. Experimental results the under circumstances of no load connected to the converter, pure three-phase resistive loads, three-phase unbalanced resistive' loads and the series resistor-inductor loads. /Imperial Users onl

Density matrix of chaotic quantum systems

The nonequilibrium dynamics in chaotic quantum systems denies a fully understanding up to now, even if thermalization in the long-time asymptotic state has been explained by the eigenstate thermalization hypothesis which assumes a universal form of the observable matrix elements in the eigenbasis of Hamiltonian. It was recently proposed that the density matrix elements have also a universal form, which can be used to understand the nonequilibrium dynamics at the whole time scale, from the transient regime to the long-time steady limit. In this paper, we numerically test these assumptions for density matrix in the models of spins.Comment: 6 pages, 5 figure

Lymphocyte evolution and ontogeny in non-eutherian mammals

Based on their different reproductive modes and evolutionary history, extant mammals are divided into three lineages: eutherians, marsupials and monotremes. Marsupials are the closest relatives to eutherians. They are born immune-incompetent. The characteristic that they develop their immune system postnatally makes them unique models to study newborn immune development and maternal immunology. As monotremes comprises the basal lineage of mammals, the study of monotreme immunology will provide unique insights regarding the origin of the mammalian immune system. Unfortunately, compared to our in-depth knowledge of eutherian immunology, especially humans and mice, knowledge of marsupial and monotreme immunology is scarce. The goal of the first part of this research was to investigate the development of immune-competence in a model marsupial, the gray short-tailed opossum, Monodelphis domestica. This research specifically looked at the ontogeny of B cells with emphasis on diversity of immunoglobulin genes during postnatal development. It takes advantage of genomic resources available for the opossum and a captive colony at the UNM Biology Department. To achieve these goals, the content and genomic organization of Ig heavy chain and light chain loci was determined. Opossum Ig heavy chain are of low germ-line diversity while light chains have high germ-line diversity. This suggests that opossums rely more on light chains than heavy chains for repertoire diversity (Wang et al. 2009). Using the detailed genomic information available of Ig loci, the timing of B cell ontogeny and Ig repertoire diversity was then determined. Opossum newborns start heavy chain VDJ recombination within the first 24 hours postpartum. The expression of the surrogate L chains occurs at day 6 postnatally. The subsequent rearrangement of the Ig\u03bb and Ig\u03ba L chain genes occur at days 7 and 8 postnatal, respectively. The diversity of early B cell H chains is limited and reduced in N region additions, as has been seen in fetal humans and mice, but lacks bias in the V, D and J segments used. Different from H chains, L chains develop much more diverse VJ recombinations and high IgL repertoire diversity when first expressed. Collectively the results demonstrate that B cell development is entirely postnatal in the opossum. The earliest time-point that an opossum has mature B cells is at the starting the second week of life (Wang et al. in preparation). These results are consistent with earlier work demonstrating that most marsupial species, including opossums are unable to generate an antibody response until the second week. A second goal of my research was the characterization of a novel T cell receptor in the duckbill platypus Ornithorhynchus anatinus. Although different from the previous goal, it nonetheless uses a non-eutherian model to address broader questions regarding immunoglobulin and T cell receptor gene evolution. TCRμ is a new T cell receptor that was first identified in marsupials and does not exist in eutherians (Parra et al. 2007). Homology searches of the platypus genome with opossum TCRμ sequence have identified a homologue of this unconventional TCRμ in platypus. Platypus TCRμ is expressed in a double V domains structure and these resemble Ig V more than conventional TCR V domains. Different from opossum TCRμ, platypus TCRμ requires two rounds of somatic recombination to assemble both V domains. The identification of TCRμ in platypus indicates that TCRμ as an ancient T cell receptor has been lost in eutherians

The Study of Ideological Education of College Students in Minority Areas of China

The ideological education of college students in minority areas of China plays an important role in the nation’s educational strategy. The contents, management, methods, features, and carriers of ideological education constitute the main parts of it. Teachers should recognize the unique features of ideological education, enrich the contents of it, consolidate the relevant management, and utilize the carriers of it appropriately. Moreover, some problems which exist in ideological education must draw people’s attention. It is necessary for college leaders and teachers to take some coping strategies on the basis of analyzing these problems

Actin-Based Feedback Circuits in Cell Migration and Endocytosis

In this thesis, we study the switch and pulse functions of actin during two important cellular processes, cell migration and endocytosis. Actin is an abundant protein that can polymerize to form a dendritic network. The actin network can exert force to push or bend the cell membrane. During cell migration, the actin network behaves like a switch, assembling mostly at one end or at the other end. The end with the majority of the actin network is the leading edge, following which the cell can persistently move in the same direction. The other end, with the minority of the actin network, is the trailing edge, which is dragged by the cell as it moves forward. When subjected to large fluctuations or external stimuli, the leading edge and the trailing edge can interchange and change the direction of motion, like a motion switch. Our model of the actin network in a cell reveals that mechanical force is crucial for forming the motion switch. We find a transition from single state symmetric behavior to switch behavior, when tuning parameters such as the force. The model is studied by both stochastic simulations, and a set of rate equations that are consistent with the simulations. Endocytosis is a process by which cells engulf extracellular substances and recycle the cell membrane. In yeast cells, the actin network is transiently needed to overcome the pressure difference across the cell membrane caused by turgor pressure. The actin network behaves like a pulse, which assembles and then disassembles within about 30 seconds. Using a stochastic model, we reproduce the pulse behaviors of the actin network and one of its regulatory proteins, Las17. The model matches green fluorescence protein (GFP) experiments for wild-type cells. The model also predicts some phenotypes that modify or diminish the pulse behavior. The phenotypes are verified with both experiments performed at Washington University and with other groups\u27 experiments. We find that several feedback mechanisms are critical for the pulse behavior of the actin network, including the autocatalytic assembly of F-actin, the negative feedback of F-actin on Las17, and the autocatalytic self-assembly of Las17. These feedback mechanisms are also studied by a simple ordinary differential equation (ODE) model. Finally, we develop a partial differential equation (PDE) model that is more realistic than the ODE model and more computationally efficient than the stochastic model. We use the PDE model to explore the rich spectrum of behaviors of the actin network beyond pulses, such as oscillations and permanent patches. The predictions of the PDE model are of high interest for suggesting future experiments that can test the model

Anti-asthmatic effect of laurotetanine extracted from Litsea cubeba (Lour.) Pers. root on ovalbumin-induced allergic asthma rats, and elucidation of its mechanism of action

Purpose: To investigate the anti-asthmatic effect of laurotetanine on allergic asthma rat model. Methods: Laurotetanine was extracted from the roots of Litsea cubeba (Lour.) Pers. Asthma was induced in rats by ovalbumin injection. Laurotetanine (20, 40, or 60 mg/kg) was administered orally to the rats for 21 days. Inflammatory cells and cytokines released by T-cell subsets Th1 and Th2 in the bronchoalveolar lavage fluid were determined. Serum immunoglobulin E (IgE) and histamine, in addition to expression of mucin 5AC (MUC-5AC), nuclear factor-kappa B (NF-κB), and an inhibitor of NF-κB (IκB) in lung tissues were also evaluated. Results: Laurotetanine treatment (20, 40, 60 mg/kg) significantly reduced inflammatory cells, including eosinophils, neutrophils, lymphocytes, and macrophages in treated rats compared with control animals (p < 0.01). Inflammatory cytokines, viz, interleukin (IL) -4, IL-6, IL-13 were also significantly (p < 0.01) decreased by laurotetanine treatment (20, 40, 60 mg/kg), whereas interferon gamma (IFN-γ) was increased (p < 0.01). Serum IgE and histamine were significantly reduced (p < 0.01) by laurotetanine (20, 40, 60 mg/kg). Furthermore, MUC5AC expression in lung tissues was significantly (p < 0.01) downregulated by laurotetanine (20, 40, and 60 mg/kg, but NF-κB and IκB were significantly (p < 0.01) upregulated by laurotetanine (20, 40, and 60 mg/kg). Conclusion: Laurotetanine exerts an anti-asthmatic effect in rats by inhibition of IgE, histamine, and inflammatory reactions via down-regulating MUC5AC and NF-κB signaling pathways. This finding justifies the need for further development of laurotetanine as a potential anti-asthmatic drug