23 research outputs found
Iron Contamination Mechanism and Reaction Performance Research on FCC Catalyst
FCC (Fluid Catalytic Cracking) catalyst iron poisoning would not only influence units’ product slate; when the poisoning is serious, it could also jeopardize FCC catalysts’ fluidization in reaction-regeneration system and further cause bad influences on units’ stable operation. Under catalytic cracking reaction conditions, large amount of iron nanonodules is formed on the seriously iron contaminated catalyst due to exothermic reaction. These nodules intensify the attrition between catalyst particles and generate plenty of fines which severely influence units’ smooth running. A dense layer could be formed on the catalysts’ surface after iron contamination and the dense layer stops reactants to diffuse to inner structures of catalyst. This causes extremely negative effects on catalyst’s heavy oil conversion ability and could greatly cut down gasoline yield while increasing yields of dry gas, coke, and slurry largely. Research shows that catalyst’s reaction performance would be severely deteriorated when iron content in E-cat (equilibrium catalyst) exceeds 8000 μg/g
See How You Read? Multi-Reading Habits Fusion Reasoning for Multi-Modal Fake News Detection
The existing approaches based on different neural networks automatically capture and fuse the multimodal semantics of news, which have achieved great success for fake news detection. However, they still suffer from the limitations of both shallow fusion of multimodal features and less attention to the inconsistency between different modalities. To overcome them, we propose multi-reading habits fusion reasoning networks (MRHFR) for multi-modal fake news detection. In MRHFR, inspired by people's different reading habits for multimodal news, we summarize three basic cognitive reading habits and put forward cognition-aware fusion layer to learn the dependencies between multimodal features of news, so as to deepen their semantic-level integration. To explore the inconsistency of different modalities of news, we develop coherence constraint reasoning layer from two perspectives, which first measures the semantic consistency between the comments and different modal features of the news, and then probes the semantic deviation caused by unimodal features to the multimodal news content through constraint strategy. Experiments on two public datasets not only demonstrate that MRHFR not only achieves the excellent performance but also provides a new paradigm for capturing inconsistencies between multi-modal news
Cost-effectiveness analysis of renal replacement therapy strategies in Guangzhou city, southern China
Objectives This study aims to assess the cost-effectiveness of three renal replacement therapy (RRT) modalities as well as proposed changes of scheduled policies in RRT composition in Guangzhou city.Methods From a payer perspective, we designed Markov model-based cost-effectiveness analyses to compare the cost-effectiveness of three RRT modalities and four different scheduled policies to RRT modalities in Guangzhou over three time horizons (5, 10 and 15 years). The current situation (scenario 1: haemodialysis (HD), 73%; peritoneal dialysis (PD), 14%; kidney transplantation (TX), 13%) was compared with three different scenarios: an increased proportion of incident RRT patients on PD (scenario 2: HD, 47%; PD, 40%; TX, 13%); on TX (scenario 3: HD, 52%; PD, 14%; TX, 34%); on both PD and TX (Scenario 4: HD, 26%; PD, 40%; TX, 34%).Results Over 5-year time horizon, HD was dominated by PD. At a willingness-to-pay (WTP) threshold of US35 518 per quality-adjusted life year (QALY) gained. The scenario 2 held a dominant position over the scenario 1, with a net saving of US44 300. The above results were consistent across the three time horizons.Conclusions TX is the most cost-effective RRT modality, followed in order by PD and HD. The strategy with an increased proportion of incident patients on PD and TX is cost-effective compared with the current practice pattern at the given WTP threshold. The planning for RRT service delivery should incorporate efforts to increase the utilisation of PD and TX in China
Crystalline Colloidal Array of Water Voids in Hydrogels: Direct Evidence for Entropic Trapping of Flexible Polymers
Fortuitously Superimposed Lattice Plane Secondary Diffraction from Crystalline Colloidal Arrays
Preliminary Investigation of the Feasibility of Using a Superpave Gyratory Compactor to Design Cement-Treated Aggregate Mixture
Cement-treated aggregate mixture (CTAM) is widely used in many countries. To design this mixture using the vibration compaction method brings about many problems, such as serious inconsistencies in key parameters and strong vibration energy and noise imposed on adjacent buildings and people. This work presents a preliminary investigation of the use of Superpave gyratory compactor, which has been widely used to compact hot mix asphalt in the laboratory, to design CTAM. The 3-2-2 mode of the locking point was used to determine that the gyration compaction number Ndesign should be 105. The performances of the CTAM specimens prepared using gyration compaction were compared with those prepared using the Proctor and vibration compaction methods. Compared with Proctor and vibration compaction, gyration compaction had a smaller influence on aggregate degradation. Also, the optimal moisture content after gyration compaction was the minimum. The index values for maximum dry density, unconfined compressive strength and dry/temperature shrinkage coefficient after gyration compaction were between those for Proctor compaction and vibration compaction. It can be concluded that it is feasible to design CTAM by using a Superpave gyratory compactor to compact the mixture for 105 cycles
Data Mining for Selective Visualization of Large Spatial Datasets
Data mining is the process of extracting implicit, valuable, and interesting information from large sets of data. Visualization is the process of visually exploring data for pattern and trend analysis, and it is a common method of browsing spatial datasets to look for patterns. However, the growing volume of spatial datasets make it difficult for humans to browse such datasets in their entirety, and data mining algorithms are needed to filter out large uninteresting parts of spatial datasets. We construct a web-based visualization software package for observing the summarization of spatial patterns and temporal trends. We also present data mining algorithms for filtering out vast parts of datasets for spatial outlier patterns. The algorithms were implemented and tested with a real-world set of Minneapolis-St. Paul(Twin Cities) traffic data
Visual prognosis and complications of congenital ectopia lentis: study protocol for a hospital-based cohort in Zhongshan Ophthalmic Center
Introduction Congenital ectopia lentis (CEL) is a rare ocular disease characterised by the dislocation or displacement of the lens. Patients with mild lens dislocations can be treated with conservative methods (eg, corrective eyeglasses or contact lenses). In contrast, patients with severe CEL usually require surgical management. However, few studies have focused on the visual prognosis and complications in conservative and surgical management of patients. This study aims to investigate the prognosis and complications in patients with CEL with conservative and surgical management, which is vital for CEL management, especially the choice of surgical timing and surgical method.Methods and analysis A cohort study will be conducted at Zhongshan Ophthalmic Center. We plan to recruit 604 participants diagnosed with CEL and aged ≥3 years old. Patients with mild lens subluxation and stable visual conditions will be included in the non-surgical group and follow-up at 1, 2 and 3 years after enrolment. Patients with severe lens subluxation who accept CEL surgery will be included in the surgical group. Different surgical techniques, including phacoemulsification, in-the-bag intraocular lens implantation (with or without capsular tension ring) and trans-scleral fixation, will be used depending on the severity of dislocation. Patients will be followed up at 3 months, and 1, 2 and 3 years postoperatively. Over a 5-year follow-up period, patients will receive a detailed ocular examination, including optometry, biological measurement, specular microscopy, ultrasound biomicroscopy, anterior segment and posterior segment optical coherence tomography (OCT), OCT angiography, echocardiography and questionnaires on vision-related quality of life. The primary outcome is the change of best-corrected visual acuity and the incidence of complications in both groups.Ethics and dissemination Ethics approval was obtained from the ethics committee of the Zhongshan Ophthalmic Center (number: 2022KYPJ207). Study findings will be published in a peer-reviewed journal.Trial registration number NCT05654025
Organic-Free Synthesis of Zeolite Y with High Si/Al Ratios: Combined Strategy of In Situ Hydroxyl Radical Assistance and Post-Synthesis Treatment
[EN] Zeolite Y, with a high SiO2/Al(2)O(3)ratio (SAR), plays an important role in fluidized catalytic cracking processes. However, in situ synthesis of zeolite Y with high SARs remains a challenge because of kinetic limitations. Here, zeolite Y with an SAR of 6.35 is synthesized by a hydroxyl radical assisted route. Density-functional theory (DFT) calculations suggest that hydroxyl radicals preferentially enhanced the formation of Si-O-Si bonds, thus leading to an increased SAR. To further increase the SAR, a dealumination process was carried out using citric acid, with a subsequent second-step hydrothermal crystallization, giving an SAR of up to 7.5 while maintaining good crystallinity and high product yield. The resultant zeolite Y shows good performance in cumene cracking. Introduced here is a new strategy for synthesizing high SAR zeolite Y, which is widely used in commercial applications.We thank the National Natural Science Foundation of China (Grant 21920102005, 21621001 and 21835002), the National Key Research and Development Program of China (Grant 2016YFB0701100), the 111 Project (B17020), and the Spanish Government-MINECO (SEV-2016-0683 and MAT2017-82288-C2-1-P (AEI/FEDER, UE)) for supporting this work. P. F. thanks ITQ for his contract.Wang, J.; Liu, P.; Boronat Zaragoza, M.; Ferri-Vicedo, P.; Xu, Z.; Liu, P.; Shen, B.... (2020). Organic-Free Synthesis of Zeolite Y with High Si/Al Ratios: Combined Strategy of In Situ Hydroxyl Radical Assistance and Post-Synthesis Treatment. Angewandte Chemie International Edition. 59(39):17225-17228. https://doi.org/10.1002/anie.202005715S17225172285939Martínez, C., & Corma, A. (2011). Inorganic molecular sieves: Preparation, modification and industrial application in catalytic processes. 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