All-Solution-Processed Transparent Conductive Electrodes with Crackle Templates:

Thesis advisor: Michael J. NaughtonIn this dissertation, I first discuss many different kinds of transparent conductors in Chapter one. In Chapter two, I focus on transparent conductors based on crackle temples. I and my colleagues developed three (one sputter-free and two fully all-solution) methods to fabricate metallic networks as transparent conductors. The first kind of all-solution process is based on crackle photolithography and the resulting silver networks outperform all reported experimental values, including having sheet resistance more than an order of magnitude lower than ITO, yet with comparable transmittance. The second kind of all-solution proceed transparent conductor is obtained by integrating crackle photolithography-based microwires with nanowires and electroplate welding. This combination results in scalable film structures that are flexible, indium-free, vacuum-free, lithographic-facility-free, metallic-mask-free, with small domain size, high optical transmittance, and low sheet resistance (one order of magnitude smaller than conventional nanowire-based transparent conductors).Thesis (PhD) — Boston College, 2019.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Physics

Patterns and driving factors of leaf C, N, and P stoichiometry in two forest types with different stand ages in a mid-subtropical zone

Background: Carbon (C), nitrogen (N), and phosphorus (P) stoichiometry is a key indicator of nutrient utilization in plants, and C/N/P ratios are related to the life histories and adaptation strategies of tree species. However, no consensus has been reached on how leaf stoichiometric characteristics are affected by forest type and stand ages. The relationships between leaf stoichiometry and geographical, meteorological, and soil factors also remain poorly understood. Methods: Leaf and soil were sampled from forest stands of different age groups (young, middle-aged, near-mature, and mature) in two forest types (Chinese fir (Cunninghamia lanceolata) forests and evergreen broadleaved forests). The relationships between leaf C, N, and P stoichiometric parameters and geographical, meteorological, and soil factors were analysed by using redundancy analysis (RDA) and stepwise linear regression analysis. Results: Leaf C concentrations peaked in the near-mature stands with increasing age irrespective of forest type. Leaf N and P concentrations fluctuated with a rising trend in Chinese fir forests, while decreased first and increased later from young to mature phases in natural evergreen broadleaved forests. Chinese fir forests were primarily limited by N and P, while natural evergreen broadleaved forests were more susceptible to P limitation. Leaf C, N, and P stoichiometric characteristics in Chinese fir forests were mainly affected by the soil total P concentration (SP), longitude (LNG), growing season precipitation (GSP) and mean temperature in July (JUT). The leaf C concentration was mainly affected by GSP and JUT; leaf N and P concentrations were both positively correlated with LNG; and leaf P was positively correlated with SP. In evergreen broadleaved forests, however, leaf stoichiometric parameters displayed significant correlations with latitude (LAT) and mean annual precipitation (MAP). Conclusions: Leaf stoichiometry differed among forest stands of different age groups and forest types. Leaf C, N, and P stoichiometry was primarily explained by the combinations of SP, LNG, GSP and JUT in Chinese fir forests. LAT and MAP were the main controlling factors affecting the variations in the leaf C, N, and P status in natural evergreen broadleaved forests, which supports the temperature-plant physiological hypothesis. These findings improve the understanding of the distribution patterns and driving mechanisms of leaf stoichiometry linked with stand age and forest type

Numerical investigation of cycle performance in compressed air energy storage in aquifers

Compressed air energy storage (CAES) is one of the promising technologies to store the renewable energies such as surplus solar and wind energy in a grid scale. Due to the widespread of aquifers in the world, the compressed air energy storage in aquifers (CAESA) has advantages compared with the compressed air energy storage in caverns and air tanks. The feasibility of aquifers as storage media in CAES system has been demonstrated by numerical models and field tests. This study proposes a numerical model by Transport of Unsaturated Groundwater and Heat Version 3.0/Equation-of-State 3 (TOUGH3/EOS3) to simulate a field-scale study of a novel CAES by storing the compressed air in aquifers. The feasibility of the model has been demonstrated by comparison of simulation results and monitoring data. After that, three types of cycles, which are daily cycle, weekly cycle and monthly cycle, are designed to study their performance within a month working cycle. Their gas saturation show small differences after one month cycle. When the air with temperature of 50 °C injected into aquifers with temperature of 20 °C, after the cycle finished, the air temperature in aquifer of daily cycle are 5.4 °C higher than that of weekly cycle and 10.8 °C higher than that of monthly cycle. It is indicated that during the same cycle periods, the more cycle times, the higher air temperature in aquifers after the cycle. The energy recovery efficiencies for daily cycle, weekly cycle and monthly cycle are 96.96%, 96.27% and 93.15%, respectively. The slight increase of energy recovery efficiencies from daily cycle to monthly cycle indicate that with the same energy storage scales, the energy produced by daily cycle has slight competitiveness. The simulation results can provide references for engineering application in future

Leaf structural traits vary with plant size in even-aged stands of Sapindus mukorossi

Sapindus mukorossi Gaertn., an important oleaginous woody plant, has garnered increasing research attention owing to its potential as a source of renewable energy (biodiesel). Leaf structural traits are closely related to plant size, and they affect the fruit yield and oil quality. However, plant size factors that predominantly contribute to leaf structural traits remain unknown. Therefore, the purpose of this study was to understand the associations between leaf structural traits and plant size factors in even-aged stands of S. mukorossi. Results showed that leaf length (LL) and leaf area (LA) markedly increased with the increasing diameter at breast height (DBH) and tree height (TH), although other leaf structural traits did not show noticeable changes. Difference in slopes also indicated that the degree of effect of plant size factors on leaf structural traits was in the order of TH > DBH. Leaf structural traits showed no systematic variation with crown width (CW). LA was significantly positively correlated with LL, leaf width (LW), LL/LW, and leaf thickness (LT) and was significantly but negatively correlated with leaf tissue density (LTD) and leaf dry mass content (LDMC). Specific leaf area showed a significantly negative correlation with LT, LDMC, and LTD. LTD showed a significantly positive correlation with LDMC, but a negative correlation with LT. The results were critical to understand the variability of leaf structural traits with plant size, can provide a theoretical foundation for further study in the relationship between leaf structural traits and fruit yield, and regulate leaf traits through artificial management measures to promote plant growth and fruit yield

Regulatory and functional divergence among members of Ibβfruct2, a sweet potato vacuolar invertase gene controlling starch and glucose content

Sweet potato [Ipomoea batatas (L.) Lam.] is an important food and industrial crop. Its storage root is rich in starch, which is present in the form of granules and represents the principal storage carbohydrate in plants. Starch content is an important trait of sweet potato controlling the quality and yield of industrial products. Vacuolar invertase encoding gene Ibβfruct2 was supposed to be a key regulator of starch content in sweet potato, but its function and regulation were unclear. In this study, three Ibβfruct2 gene members were detected. Their promoters displayed differences in sequence, activity, and cis-regulatory elements and might interact with different transcription factors, indicating that the three Ibβfruct2 family members are governed by different regulatory mechanisms at the transcription level. Among them, we found that only Ibβfruct2-1 show a high expression level and promoter activity, and encodes a protein with invertase activity, and the conserved domains and three conserved motifs NDPNG, RDP, and WEC are critical to this activity. Only two and six amino acid residue variations were detected in sequences of proteins encoded by Ibβfruct2-2 and Ibβfruct2-3, respectively, compared with Ibβfruct2-1; although not within key motifs, these variations affected protein structure and affinities for the catalytic substrate, resulting in functional deficiency and low activity. Heterologous expression of Ibβfruct2-1 in Arabidopsis decreased starch content but increased glucose content in leaves, indicating Ibβfruct2-1 was a negative regulator of starch content. These findings represent an important advance in understanding the regulatory and functional divergence among duplicated genes in sweet potato, and provide critical information for functional studies and utilization of these genes in genetic improvement

Validation of Shielding Analysis Capability of SuperMC with SINBAD

Abstract: The shielding analysis capability of SuperMC was validated with the Shielding Integral Benchmark Archive Database (SINBAD). The SINBAD was compiled by RSICC and NEA, it includes numerous benchmark experiments performed with the D-T fusion neutron source facilities of OKTAVIAN, FNS, IPPE, etc. The results from SuperMC simulation were compared with experimental data and MCNP results. Very good agreement with deviation lower than 1% was achieved and it suggests that SuperMC is reliable in shielding calculation

Mapping the Influence of Land Use/Land Cover Changes on the Urban Heat Island Effect—A Case Study of Changchun, China

The spatio-temporal patterns of land use/land cover changes (LUCC) can significantly affect the distribution and intensity of the urban heat island (UHI) effect. However, few studies have mapped a clear picture of the influence of LUCC on UHI. In this study, both qualitative and quantitative models are employed to explore the effect of LUCC on UHI. UHI and LUCC maps were retrieved from Landsat data acquired from 1984, 1992, 2000, 2007, and 2014 to show their spatiotemporal patterns. The results showed that: (1) both the patterns of LUCC and UHI have had dramatic changes in the past 30 years. The urban area of Changchun increased more than four times, from 143.15 km2 in 1984 to 577.45 km2 in 2014, and the proportion of UHI regions has increased from 15.27% in 1984 to 29.62% in 2014; (2) the spatiotemporal changes in thermal environment were consistent with the process of urbanization. The average LST of the study area has been continuously increasing as many other land use types have been transformed to urban regions. The mean temperatures were higher in urban regions than rural areas over all of the periods, but the UHI intensity varied based on different measurements; and (3) the thermal environment inside the city varied widely even within a small area. The LST possesses a very strong positive relationship with impervious surface area (ISA), and the relationship has become stronger in recent years. The UHI we employ, specifically in this study, is SUHI (surface urban heat island)

The Cooling Effect of Urban Parks and Its Monthly Variations in a Snow Climate City

Urban parks have been shown to form park cool islands (PCIs), which can effectively alleviate the negative influences of urban heat islands (UHI). However, few studies have examined the detailed characteristics of PCIs, the effect of urban park features on their individual temperatures, and monthly variation in PCIs. Land surface temperature (LST) retrieved from Landsat 8 TIR images between May and October were used to represent the thermal environment. Urban park characteristics were extracted from high-resolution GF-2 images. Using these datasets, the relationships between urban park characteristics and PCIs were explored in this study using Changchun, which has a snow climate, as a case study. The results showed the following: (1) the urban parks exhibited a cooling island effect, and the PCIs showed significant monthly variations with the highest intensities in the hot months; (2) the effects of composition (e.g., park size and the percentage of water area) on LSTs and PCIs showed significant monthly variability and were stronger than the configuration effects. Furthermore, an unexpected, negative correlation between PCIs and the area of park grass was also found; and (3) larger parks tended to have stronger PCI intensities and extents of influence. For parks larger than 30 ha, the cooling effects extended approximately 480 m from the park edge between June and August. For all of parks during the study duration, the rate of temperature increase was highest within 60 m from the park edge. The PCI we employ specifically in this study is characterized by LST

Distributed Network Image Processing System and Transmission Control Algorithm

With the increasing use of Internet technologies, image data is spreading more and more on the Internet. Whether it is a social network or a search engine, a large amount of image data is generated. By studying the distributed network image processing system and transmission control algorithm, this paper proposes a more accurate gradient calculation method based on the SIFT algorithm. It is concluded that the performance of the proposed algorithm is slightly better than that of the original algorithm, so the system is implemented. On the basis of reducing the performance of the original algorithm, the dimension of the image features is effectively reduced. By comparing the influence of the image retrieval system in the single-machine environment and the distributed environment on the image feature extraction rate, it is proved that the system uses five distributed nodes to construct the image transmission system that achieves the best results in terms of machine cost and system performance. The random Gaussian orthogonal matrix is analyzed with good stability and performance. The OMP algorithm has good convergence and reconstruction performance. The MH-BCS-SPL reconstruction algorithm works best, and the PSNR decreases very smoothly in the process of increasing the packet loss rate from 0.1 to 0.6. The experimental results show that different orthogonal bases behave differently under different images. Overall, the BCS-SPL series algorithm has greatly improved the reconstruction effect compared with the traditional OMP algorithm