2nd Place Solution to Google Landmark Retrieval 2020

This paper presents the 2nd place solution to the Google Landmark Retrieval Competition 2020. We propose a training method of global feature model for landmark retrieval without post-processing, such as local feature and spatial verification. There are two parts in our retrieval method in this competition. This training scheme mainly includes training by increasing margin value of arcmargin loss and increasing image resolution step by step. Models are trained by PaddlePaddle framework and Pytorch framework, and then converted to tensorflow 2.2. Using this method, we got a public score of 0.40176 and a private score of 0.36278 and achieved 2nd place in the Google Landmark Retrieval Competition 2020

COVID-19 Shock and the Time-Varying Volatility Spillovers Among the Energy and Precious Metals Markets: Evidence From A DCC-GARCH-CONNECTEDNESS Approach

The outbreak of the COVID-19 epidemic intensified the volatility of commodity markets (the energy and precious metals markets), which created a significant negative impact on the volatility spillovers among these markets. It may also have triggered a new volatility risk contagion. In this paper, we introduce the DCC-GARCH-CONNECTEDNESS approach to explore the volatility spillover level and multi-level spillover structure characteristics among the commodity markets before and during the COVID-19 epidemic in order to clarify the new volatility risk contagion patterns across the markets. The results implied several conclusions. (i) The COVID-19 epidemic has significantly improved the total volatility spillover level of the energy and precious metals markets and has enhanced the risk connectivity among the markets. (ii) The COVID-19 epidemic has amplified the volatility of the crude oil market, making it the main volatility spillover market, namely the source of volatility risk contagion. (iii) The COVID-19 epidemic outbreak enhanced the external risk absorption capacity of the natural gas and silver markets, and the absorption level of the external volatility spillover improved significantly. Furthermore, the risk absorption capacity of the gold market weakened, while the gold market has remained the endpoint of external volatility risk during the epidemic and has acted as a risk stabilizer. (iv) The volatility spillover among markets has clear time-varying characteristics and a positive connectedness with the severity of the COVID-19 epidemic. As the severity of the COVID-19 epidemic increases, the volatility risk connectivity among the markets rapidly increases

ARID1A Deficiency Impairs the DNA Damage Checkpoint and Sensitizes Cells to PARP Inhibitors

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Optimal planning of electric-heating integrated energy system in low-carbon park with energy storage system

Electric-heating integrated energy system (EH-IES) is pivotal for advancing energy structure reforms, and proper planning of EH-IES components can markedly enhance the operation economy, environmental sustainability, and system stability. Nonetheless, the inherent randomness and intermittency of renewable energy sources, along with the peak and valley characteristics of the load, cause output fluctuations in EH-IES energy supply equipment, posing significant threats to system stability. To address these challenges, a multi-objective bi-layer EH-IES planning model considering energy storage system is established, aiming at optimizing both economic performance and stability. This model employs non-dominated sorting genetic algorithm II (NSGA II) to optimally plans the capacity and location of EH-IES's equipment under 13-node district heating network (DHN), IEEE-33, and IEEE-69 node test systems. Simulation results show that DHN's thermal customer satisfaction is improved by 77.19 % (7.076 °C), with the total cost is $234,310.09/day. For the distributed network (DN), the net load fluctuation is reduced by 1.8491 MW (23.38$403.17 and $898.36. Consequently, the proposed method can improve the cost efficiency and sustainability of the system operation

Enhanced ozone mass transfer and organic (micro)pollutant removal in packed bubble columns

Ozone-based processes are effectively used for e.g. removing organic (micro)pollutants from municipal secondary effluent and oxidizing contaminants from industrial wastewater. Nevertheless, the practical application of the ozonation technique is still facing some challenges. The first one is the formation of oxidation intermediates owing to the low mineralization efficiency during ozonation. Second, the low ozone gas/liquid mass transfer limits the overall oxidation reaction efficiency. As ozone gas generation is an energy-intensive process, this also reduces the cost-effectiveness. As such, enhancing the ozone mass transfer and achieving high ozonation efficiency at low energy consumption is essential for expanding the practical application of ozonation. The third challenge is related to the elimination of micropollutants by ozonation. It is difficult to monitor the removal efficiency of micropollutants in real-time because frequent (chromatography based) analysis of each compound with low concentrations is costly and time-consuming. As such, developing reliable and efficient online-monitoring methods for micropollutants removal during ozonation is needed. Based on these challenges, the first chapter gives a critical literature review on the ozonation process and ozone mass transfer enhancement techniques. According to this review, applying granular mineral solids as active packing materials in a packed ozone reactor, which has not yet been studied, is proposed to be a promising method to improve the ozone mass transfer and oxidation efficiency. Additionally, the research progress in surrogate-based monitoring and control strategies of micropollutants ozonation is reviewed in Chapter 1. The removal of dissolved organic matters (DOM, mainly represent by UV254) can be used as a reliable and robust surrogate to monitoring the removal of micropollutants in a conventional bubble column. However, its feasibility in the application of packed columns has not yet been investigated. Based on these research gaps, this thesis is mainly working on using mineral-packed bubble columns to enhance the ozone mass transfer, achieve high target organic (micro)pollutants removal, and reduce oxidation intermediates generation with low energy consumption. The feasibility of combining ozonation in packed bubble columns with other treatments was also studied. The specific research aims are listed in Chapter 2. The outline of this thesis is also shown in Chapter 2. The details of the experiment setups, materials, and methods are given in Chapter 3. In this thesis, lava rock, metal pall rings and expanded clay aggregates (ECA) were used as packing materials to build packed bubble column (LBC, MBC, and EBC, respectively) and compared with non-packed bubble column (BC). In Chapter 4, the ozone gas/liquid mass transfer efficiency in BC, MBC and LBC was determined in a countercurrent continuous mode by calculating the height of packing equivalent to one transfer unit (HOG), where a lower HOG represents a higher mass transfer efficiency. Compared with the HOG value of BC (17 m), that of LBC (6 m) and MBC (11 m) was 65% and 35% lower. Furthermore, in Chapter 5 and 6, ozone mass transfer tests were conducted in semi-batch mode to determine their volumetric mass transfer coefficient values k_L a of ozone at pH=7 and T=20 °C. The LBC had the highest value 0.62 min-1, followed by EBC (0.58 min-1), MBC (0.42 min-1) and BC (0.24 min-1), showing the packed bubble columns increased the ozone gas-liquid mass transfer efficiency and lava rock had the best promoting performance. Meanwhile, the effect of these packing materials on the organic pollutants (focusing on DOM and specific micropollutants) degradation by ozonation was studied. In Chapter 4 humic acids (HA) were used as model pollutant to evaluate the ozonation performance of different columns since HA is widely present in natural water and various types of wastewater and has adverse effects on water quality. The use of LBC and MBC increased the HA removal efficiency by 19%~26% at 33.3 mg/(Lcolumn h) (i.e. 0.8 g O3/g COD) of ozone dose, compared to BC. The O3 utilization efficiency was improved by up to 42% and the energy consumption (EEO) for HA removal was decreased by 5%~51%. In Chapter 5 and 6, LBC, MBC and BC were used to ozonate real wastewater (bio-treated landfill leachate) which contains bio-refractory organic compounds including DOM and micropollutants. In Chapter 5 mainly the DOM removal from bio-treated landfill leachate was investigated. Insight into the formation of oxidation intermediates from DOM in the leachate during ozonation was provided. At an O3 dose of 0.6 g O3/g COD, the COD removal efficiency was 32% in MBC and 46% in LBC, which was 6% and 20% higher than that in BC (26%). The presence of lava rock decreased the energy consumption for COD removal by about 53%, i.e. from 38 kWh/m3 in BC to 18 kWh/m3 in LBC. The lowest operating cost for per kilogram COD removal (2.53 €/kg COD) was achieved in LBC. Gas chromatography–mass spectrometry (GC-MS) analysis showed that MBC and LBC improved the further oxidation efficiency of DOM from the bio-treated landfill leachate and reduced intermediate products during ozonation. In Chapter 6 the abatement of micropollutants from biotreated landfill leachates was investigated, as well as the correlation between micropollutant removal and the reduction of DOM represent by UV254 absorbance (ΔUV254). Results showed both mineral materials (lava rock and ECA) had a comparable beneficial effect towards micropollutants ozonation and their intermediates degradation. The removal efficiency of O3-recalcitrant compounds (diuron, atrazine (ATZ) and alachlor (ALA)) increased by 20%-40% and the ΔUV254 increased by over 20% in LBC and EBC in comparison with that in BC. In view of process control, a two-stage linear correlation between the O3-recalcitrant compounds (ATZ and ALA) removal and ΔUV254 was observed. In addition to a single stage ozonation process, the packed bubble column was used as a pre- or post- treatment unit in a treatment train in Chapter 7 and 8. In Chapter 7, the ozonation process was followed by an adsorption process to recover Ortho-phosphate (Ortho-P) from a phosphonate, i.e. 1-hydroxyethane-1,1-diphosphonic acid (HEDP) containing waste water. Mineral packed bubble columns including LBC (86%) and EBC (72%) showed higher net Ortho-P production efficiency than BC (59%). Afterwards, the produced Ortho-P in the ozonated effluents was adsorbed and recovered by a waste product, i.e. iron coated sand (ICS) granules. The highest Ortho-P recovery efficiency (66 %) was achieved by ICS adsorption after ozonation in the LBC column, followed by EBC (62 %) and BC (38 %). Furthermore, in Chapter 8, the ozonation process following a biological treatment process was studied. Considering that microorganisms might have some tolerance to ozone, chapter 8 investigated the feasibility to combine the biological treatment process with the in-situ ozonation process in the same bioreactor unit. An ECA-packed biofilm column (EBC) was run and operated for 150 days. In the first experimental period, a biodegradation process was operating at a residence time of 48 h. About 85% of the total inorganic nitrogen can be removed from the raw landfill leachate biologically. About 90% of the biodegradable micropollutants (bisphenol A, 17α-ethinylestradiol and alachlor) could be removed as well, while a large percentage of recalcitrant compounds such as carbamazepine (CBZ, around 70%) and atrazine (ATZ, about 30%) remained in the effluent. In a second experimental period, ozone gas was gradually introduced into the biofilm reactor in situ to further remove the bio-refractory micropollutants. At an ozone dose of 0.4 g O3/g COD, the residual target micropollutants (ATZ, CBZ) were completely removed. Meanwhile, the high nitrogen removal efficiency can be maintained at 85%, which was attributed to the high abundance of nitrifying and denitrifying bacteria in the reactor indicated by the results of the 16S rRNA analysis. Overall, this PhD research provides comprehensive insights into the enhanced ozone mass transfer and removal of the organic (micro)pollutants by ozonation in minerals packed bubble columns. The findings and results were discussed in Chapter 9. Some perspectives on potential future research are provided as well