44 research outputs found

    Pressure Response During Gas Diffusion in Tight Porous Media

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    In this thesis, the pressure change during countercurrent diffusion in the cyclic gas injection process was investigated. It briefly introduces the situation of climate change and the importance for considering Carbon Capture Utilization and Storage (CCUS) in the application of Enhance Gas Recovery. A real core and two compartments were used to represent the relationship in the system of fractures, porous media, and the gas reservoir. Three kinds of experiments, including single gas flooding in the core system, coupled gases diffusion without core in the system, and the most important one, coupled gases diffusion in different cores were carried out. The experimental system consists of two compartments and one core holder with the core samples in the middle. The initial conditions at the two sides of the core were set as an isobaric, both at around 40 psi (gauge pressure) to eliminate the convection effect and observing the pressure change caused by diffusion solely. Nitrogen, carbon dioxide and methane were used in different combinations to see the binary behavior in Scioto Sandstone and Torrey Sandstone. The general pressure trend for single gas flow in the cores is always decreasing at the very beginning and reaches a plateau due to the unsteady flow in the system. The binary gas behavior in no-core countercurrent diffusion is dominated by the heavier component. The binary gas behavior in the two sandstones is controlled by molecular weight at the beginning stage, but later it combines surface diffusion and sorption, rendering a more complex general behavior. The pore size also plays an important role if the pore diameter is comparable with the mean free path of the gas molecules. The response curve changes by varying the pore diameter and the critical surface area

    Aerosols Monitored by Satellite Remote Sensing

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    Aerosols, small particles suspended in the atmosphere, affect the air quality and climate change. Their distributions can be monitored by satellite remote sensing. Many images of aerosol properties are available from websites as the by-products of the atmospheric correction of the satellite data. Their qualities depend on the accuracy of the atmospheric correction algorithms. The approaches of the atmospheric correction for land and ocean are different due to the large difference of the ground reflectance between land and ocean. A unified atmospheric correction (UAC) approach is developed to improve the accuracy of aerosol products over land, similar to those over ocean. This approach is developed to estimate the aerosol scattering reflectance from satellite data based on a lookup table (LUT) of in situ measured ground reflectance. The results show that the aerosol scattering reflectance can be completely separated from the satellite measured radiance over turbid waters and lands. The accuracy is validated with the mean relative errors of 22.1%. The vertical structures of the aerosols provide a new insight into the role of aerosols in regulating Earth\u27s weather, climate, and air quality

    Novel Fast-Speed Partial-Shading-Tolerant Flexible Power Point Tracking for Photovoltaic Systems with Explicit Key Points Estimation

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    Recent power curtailment-based photovoltaic (PV) flexible power point tracking (FPPT) algorithms mainly adopted intricate curve fitting or sophisticated curve-scanning mecha-nisms to ensure the grid supportive functionalities under partial shading conditions (PSCs), showing the limitations of mathe-matical solidity or system dynamics improvement. Accordingly, a novel fast-speed partial-shading-tolerant FPPT (PST-FPPT) algorithm is proposed in this paper. Regarding the proposed scheme, a modified explicit PV model is developed to express the key operation points with the assistance of several representative current-voltage samples from the initialization process, which is beneficial to computational burden reduction and irradiance sensors removal. Additionally, to guarantee the tracking speed to system dynamics, a set point estimation-based direct voltage regulation strategy is proposed in this paper, eliminating the redundant searching in approaching the predefined power com-mand. Simulation and experimental evaluations under various PSCs and operational circumstances validated the effectiveness of the proposed control

    Boosting with an aerosolized Ad5-nCoV elicited robust immune responses in inactivated COVID-19 vaccines recipients

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    IntroductionThe SARS-CoV-2 Omicron variant has become the dominant SARS-CoV-2 variant and exhibits immune escape to current COVID-19 vaccines, the further boosting strategies are required.MethodsWe have conducted a non-randomized, open-label and parallel-controlled phase 4 trial to evaluate the magnitude and longevity of immune responses to booster vaccination with intramuscular adenovirus vectored vaccine (Ad5-nCoV), aerosolized Ad5-nCoV, a recombinant protein subunit vaccine (ZF2001) or homologous inactivated vaccine (CoronaVac) in those who received two doses of inactivated COVID-19 vaccines. ResultsThe aerosolized Ad5-nCoV induced the most robust and long-lasting neutralizing activity against Omicron variant and IFNg T-cell response among all the boosters, with a distinct mucosal immune response. SARS-CoV-2-specific mucosal IgA response was substantially generated in subjects boosted with the aerosolized Ad5-nCoV at day 14 post-vaccination. At month 6, participants boosted with the aerosolized Ad5-nCoV had remarkably higher median titer and seroconversion of the Omicron BA.4/5-specific neutralizing antibody than those who received other boosters. DiscussionOur findings suggest that aerosolized Ad5-nCoV may provide an efficient alternative in response to the spread of the Omicron BA.4/5 variant.Clinical trial registrationhttps://www.chictr.org.cn/showproj.html?proj=152729, identifier ChiCTR2200057278

    How to peak carbon emissions of provincial construction industry? Scenario analysis of Jiangsu Province

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    China has become the world's largest carbon emitter, and its commitment to peak carbon emissions by 2030 is important for global development. The construction industry is one of China's biggest carbon emitters, and its peak has a direct impact on China's carbon commitment. Due to the regional heterogeneity of different provinces, the carbon emission of construction industry (CECI) at provincial level is of unique significance. To accurately predict the peak of provincial CECI, a prediction model was established by system dynamics, including direct CECI, indirect CECI and operational CECI. Taking Jiangsu province as an example, the single and multiple scenario settings with increasing R&D investment, promoting energy-saving buildings and implementing carbon trading from 2016 to 2030 was carried out, indicating that: 1) Without any carbon emission reduction measures, the CECI would maintain an annual growth rate of 5.58% to reach 530.61 million tons by 2030, and the indirect and operational CECI account for the majority of total with an average annual growth rate of 8.02% and 2.79% respectively. 2) All three measures had good carbon reduction effects, which would reduce the total CECI by 26.46% 21.68% and 10.68% respectively by 2030, but only when implemented simultaneously can CECI peak before 2030, 308.77 million tons at 2029. In the end, three policy implications was put forward. The framework presented in this paper provided a basis for the prediction of peak CECI in a province or state, which can help policy makers plan a more reasonable low-carbon development roadmap
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