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text ; This dissertation examines the application of various classical root finding methods to digital maximum power point tracking (DMPPT). An overview of root finding methods such as the Newton Raphson Method (NRM), Secant Method (SM), Bisection Method (BSM), Regula Falsi Method (RFM) and a proposed Modified Regula Falsi Method (MRFM) applied to photovoltaic (PV) applications is presented. These methods are compared among themselves. Some of their features are also compared with other commonly used maximum power point (MPP) tracking methods. Issues found when implementing these root finding methods based on continuous variables in a digital domain are explored. Some of these discussed issues include numerical stability, digital implementation of differential operators, and quantization error. Convergence speed is also explored. The analysis is used to provide practical insights into the design of a DMPPT based on classical root finding algorithms. A new DMPPT based on a MRFM is proposed and used as the basis for the discussion. It is shown that this proposed method is faster than the other discussed methods that ensure convergence to the MPP. The discussion is approached from a practical perspective and also includes theoretical analysis to support the observations. Extensive simulation and experimental results with hardware prototypes verify the analysis. ; Electrical and Computer Engineering

The objective of the study is to: (i) assess the adequacy of the existing heat and electricity tariff levels for achieving financial viability of the energy sector operators; (ii) analyze the distributional implications of energy tariff increases; and (iii) assess the effectiveness of the existing social assistance programs and how to adjust them to mitigate the impact of energy tariff increase on the poor This report presents the key findings and recommendations for the Government of Moldova as well as other energy sector stakeholders. The report starts with a synopsis that summarizes the key findings and recommendations. The main report section starts with an introduction to country context, presents the design of tariff setting methodologies, and assesses the adequacy of tariffs based on constructed scenarios. Thereafter analysis of the distributional impact of projected range of tariff increases and the need to adjust the social assistance programs to mitigate the impact on the poor are presented. The report concludes with recommendations for the government on actions to be implemented on tariff setting methodologies and social assistance as well as areas for further research. Appendices include further background information of the analysis.

"Issued December 1980." ; "Building Economics and Regulatory Technology Division, Center for Building Technology, National Engineering Laboratory, National Bureau of Standards." ; Includes bibliographical references. ; Mode of access: Internet.

It will be important for land managers, ecological researchers and policymakers to understand how predicted climate changes may affect the flora of Illinois. A climate change vulnerability assessment was completed in 2011 for the162 Animal Species in Greatest Need of Conservation using NatureServe’s Climate Change Vulnerability Index (CCVI) tool. Here we selected 73plant species found in Illinois and calculated their relative vulnerabilities to predicted climate changes, also using the NatureServe CCVI tool. We selected species from several groups that we felt would be broadly representative of the Illinois flora. These groups included: rare plants, invasive plants, important prairie species, important woodland/savanna species, important forest species, and plants important to society. We compiled and entered data regarding both the species’ exposures to predicted climate changes and their sensitivities to those changes. Exposures were determined by overlapping species range maps for Illinois with maps of temperature and moisture (AET:PET) predictions for the middle of this century. Species sensitivities were determined by interviewing between 4 and 12 experts for each plant species. Experts answered questions found in the CCVI tool regarding the species’ biologies, ecologies and behaviors. Results for each individual survey were averaged for each species. Results fell into one of five vulnerability categories: Extremely Vulnerable, Highly Vulnerable, Moderately Vulnerable, Not Vulnerable/Presumed Stable, and Not Vulnerable/Increase Likely. Results for these 73species in Illinois fell into all 5 vulnerability categories, with the majority (67%) falling into the Presumed Stable category. The species most vulnerable to predicted climate changes were all of conservation concern; most were federal or state listed species. Native species tended to be more vulnerable than non-natives, and plants important to prairies, savannas and forests were equally vulnerable to predicted changes. The four species were ranked as ...

With high penetration of renewable energy, the cost of frequency control ancillary services (FCAS) has increased substantially and has become one of the main barriers to utilize clean and inexhaustible wind, solar and like power resources in large scale. After investigating a variety of often used energy storage devices (ESDs), the authors present a tiered energy storage system (TESS) for self-provision of regulation services by wind farms. Designed through employing different characteristics of these ESDs with respect to capacity, responding speed and investment/operation costs, the TESS can be applied for FCAS of power grids integrated with wind farms, including frequency regulation and contingency services. Simulations carried out in the research has verified the feasibility of the TESS.

Photosynthetic light-harvesting proceeds by the collection and highly efficient transfer of energy through a network of pigment-protein complexes. Inter-chromophore electronic couplings and interactions between pigments and the surrounding protein determine energy levels of excitonic states and dictate the mechanism of energy flow. The excitonic structure (orientation of excitonic transition dipoles) of pigment-protein complexes is generally deduced indirectly from x-ray crystallography in combination with predictions of transition energies and couplings in the chromophore site basis. Here, we demonstrate that coarse-grained excitonic structural information in the form of projection angles between transition dipole moments can be obtained from polarization-dependent two-dimensional electronic spectroscopy of an isotropic sample, particularly when the nonrephasing or free polarization decay signal rather than the photon echo signal is considered. The method provides an experimental link between atomic and electronic structure and accesses dynamical information with femtosecond time resolution. In an investigation of the Fenna-Matthews-Olson complex from green sulfur bacteria, energy transfer connecting two particular exciton states in the protein is isolated as being the primary contributor to a cross peak in the nonrephasing 2D spectrum at 400 fs under a specific sequence of polarized excitation pulses. The results suggest the possibility of designing experiments using combinations of tailored polarization sequencesto separate and monitor individual relaxation pathways.

"February 6, 1981." ; "Distribution category UC-63b." ; "This work was performed for the Jet Propulsion Laboratory, California Institute of Technology, under NASA Contract NAS7100 for the U.S. Department of Energy, Division of Solar Energy. The JPL Low-Cost Solar Array Project is funded by DOE and forms part of the DOE Photovoltaic Conversion Program to initiate a major effort toward the development of low-cost solar arrays." ; Includes bibliographical references. ; Mode of access: Internet.

2015 Fall. ; Includes illustrations (some color). ; Includes bibliographical references. ; Thin film heterojunction solar cells based on CuSb(S,Se)2 absorbers are investigated for two primary reasons. First, antimony is more abundant and less expensive than elements used in current thin film photovoltaics, In, Ga, and Te, and so, successful integration of Sb based materials offers greater diversification and scalability of solar energy. Second, the CuSb(S,Se)2 ternary is chemically, electronically, and optically similar to the well-known, high efficiency, CuIn(S,Se)2 based materials. It is therefore postulated that the copper antimony ternaries will have similar defect tolerant electronic transport that may allow for similar highly efficient photoconversion. However, CuSb(S,Se)2 forms a layered crystal structure, different from the tetrahedral coordination found in conventional solar absorbers, due to the non-bonding lone pair of electrons on the antimony site. Thus examination of 2D antimony ternaries will lend insight into the role of structure in photoconversion processes. To address these questions, the semiconductors of interest (CuSbS2 & CuSbSe2) were first synthesized on glass by combinatorial methods, to more quickly optimize process condi- tions. Radio-frequency (RF) magnetron co-sputtering from Sb2(S,Se)3 and Cu2(S,Se) targets were used, without rotation, to produce chemical and flux graded libraries which were then subjected to high throughput characterization of structure (XRD), composition (XRF), con- ductivity (4pp), and optical absorption (UV/Vis/NIR). This approach rapidly identified processes that generated phase pure material with tunable carrier concentration by apply- ing excess Sb2(S,Se)3 within a temperature window bound by the volatility of Sb2(S,Se)3 and stability of the ternary phase. The resulting phase pure thin films were then incor- porated into the traditional CuInGaSe2 (CIGS) substrate photovoltaic (PV) architecture, and the resulting device performance was correlated to ...

Approximately 370 million tons of plastic are being produced annually (Plastics Europe, 2020). Only a small portion is recycled due to poor waste management practices. An estimated eight million tons of plastic moves from the land to ocean every year (IUCN, 2018) while rivers transport between 1.15 and 2.41 million tons of debris into the oceans annually (Lebreton et al., 2017). The pervasiveness of microplastics (MP), plastic polymer debris less than 5mm in diameter, in aquatic environments, their ingestion by freshwater fish, and the accumulation of MP through trophic transfer in food webs raise concern for the sustainability of fisheries, food security, and public health (Campbell et al., 2017; Wagner et al., 2019). Fish are excellent indicators of aquatic ecosystem health since they integrate changes in their physical environment (Pinheiro et al., 2017). Assessing MP contamination in fish therefore provides valuable information about MP concentrations in freshwater systems and raises attention to potential risks. My research investigated how fish feeding habitats, trophic position, body size (weight and length), and species variation influence MP ingestion and accumulation in St Lawrence River freshwater fish by collecting samples of pelagic, bentho-pelagic, and benthic fish species. I hypothesized that MP particles would be present in the GI tracts of most fish samples regardless of feeding habitat since MP can be found throughout the water column in most aquatic environments, and that the GI tracts of benthic fish would contain higher concentrations of MP beads and fragments while the GI tracts of pelagic fish would contain higher concentrations of MP fibers. I expected a greater concentration of plastic particles would be found in benthic than pelagic fish because of the prevalence of MPs found in the St Lawrence River sediments (Crew et al., 2020; Castaneda et al., 2014), and the data modeling performed by Lebreton et al. (2018). To address these questions, I collected 73 fish (seven species) from the ...

Temperature and salinity are two of the key properties of ocean water masses. The distribution of these two independent but related characteristics reflects the interplay of incoming solar radiation (insolation) and the uneven distribution of heat loss and gain by the ocean, with that of precipitation, evaporation, and the freezing and melting of ice. Temperature and salinity to a large extent, determine the density of a parcel of water. Small differences in temperature and salinity can increase or decrease the density of a water parcel, which can lead to convection. Once removed from the surface of the ocean where 'local' changes in temperature and salinity can occur, the water parcel retains its distinct relationship between (potential) temperature and salinity. We can take advantage of this 'conservative' behavior where changes only occur as a result of mixing processes, to track the movement of water in the deep ocean (Figure 1). The distribution of density in the ocean is directly related to horizontal pressure gradients and thus (geostrophic) ocean currents. During the Quaternary when we have had systematic growth and decay of large land based ice sheets, salinity has had to change. A quick scaling argument following that of Broecker and Peng [1982] is: the modern ocean has a mean salinity of 34.7 psu and is on average 3500m deep. During glacial maxima sea level was on the order of {approx}120m lower than present. Simply scaling the loss of freshwater (3-4%) requires an average increase in salinity a similar percentage or to {approx}35.9psu. Because much of the deep ocean is of similar temperature, small changes in salinity have a large impact on density, yielding a potentially different distribution of water masses and control of the density driven (thermohaline) ocean circulation. It is partly for this reason that reconstructions of past salinity are of interest to paleoceanographers.